Introduction to IBM PL/1 Programming Language

Created by Sanjay Sinha 1 INTRODUCTION TO PL/1 PL/I is a structured language to develop systems and applications programs (both business and scientific). Significant features : v Allows Free format v Regards a program as a continuous stream of data v Supports subprogram and functions v Uses defaults

Created by Sanjay Sinha 2 Building blocks of PL/I : v Made up of a series of subprograms and called Procedure v Program is structured into a MAIN program and subprograms. v Subprograms include subroutine and functions. Every PL/I program consists of : v At least one Procedure v Blocks v Group

Created by Sanjay Sinha 3 v There must be one and only one MAIN procedure to every program, the MAIN procedure statement consists of : v Label v The statement ‘PROCEDURE OPTIONS (MAIN)’ v A semicolon to mark the end of the statement. Coding a Program : 1. Comment line(s) begins with /* and ends with */. Although comments may be embedded within a PL/I statements , but it is recommended to keep the embedded comments minimum.

Created by Sanjay Sinha 4 2. The first PL/I statement in the program is the PROCEDURE statement : AVERAGE : PROC[EDURE] OPTIONS(MAIN); AVERAGE -- it is the name of the program(label) and compulsory and marks the beginning of a program. OPTIONS(MAIN) -- compulsory for main programs and if not specified , then the program is a subroutine. A PL/I program is compiled by PL/I compiler and converted into the binary , Object program file for link editing .

Created by Sanjay Sinha 5 Advantages of PL/I are : 1. Better integration of sets of programs covering several applications. 2. Easier interchangeability of files 3. Fewer programs to be written in a machine oriented language. 4. Better machine utilization, greater use of channels , more flexible storage assignment, better intercept handling.

Created by Sanjay Sinha 6 The process of compiling a PL/I program and executing it in the computer’s memory takes place through JCL. Some restrictions : Col # 1 for O.S. Col # 2 - 72 for PL/I statements Col # 73 - 80 ignored by complier PL/I Language Components : 1. Character sets : 60 characters in total, A - Z , extended characters e.g # , @ , $ , 0 -9 and 21 special characters.

Created by Sanjay Sinha 7 2. Identifiers : Used to name data, procedures , files , labels of PL/I statements and keywords. An identifiers for data names , statement labels and internal procedure names may be from 1 to 30 alphabetic characters ( A – Z,@, !, #, $ ) , numeric digits (0-9) and underscore character. 3. Statement format : LABEL : KEYWORD STATEMENT OPTIONS ; the source program . A PL/I statement may be continued across several lines.One line may contain several statements terminated by semi-colon. 4. PL/I constants : A constant is a data item that does not have a name and whose value cannot change in a program. There are six types of constants , but only 2 or 3 types are used.

Created by Sanjay Sinha 8 i) Decimal Fixed-point constants ii) Decimal Floating-point constants( using E- notation). iii) Character string constants : up to 256 characters , must be enclosed by ‘ , if an apostrophe is a part of data , then it should be preceded by another apostrophe with no intervening blanks.The repetition factors can be specified. iv) Bit-string constants : It’s a series of binary digits enclosed in single quotes and followed by the letter B. Used as flag , setting 1 or 0 , repetition factor can be used. v) Binary Fixed-Point and Binary Floating-Point constants .

Created by Sanjay Sinha 9 Data types : FIXED DECIMAL Two digits/byte Comm. Appl plus sign FIXED BINARY Half word or Comm & full word scientific appl FLOAT DECIMAL Full word, Scientific appl double word or Arithmetic two double words PICTURE One digit / byte CHARACTER or One character/byte PICTURE BIT One byte Boolean oper Purpose

Created by Sanjay Sinha 10 DECLARE statement : The purposes : i) For implicit declaration ii) For data aggregation iii) For input and output files Base and Scale and precision attributes DECLARE PRICE DECIMAL FIXED(5,2) DECLARE PI FLOAT DECIMAL(6) DECLARE COUNT FIXED BINARY(15) DECLARE PI FLOAT BINARY(31) DECLARE BETA FIXED BINARY(15,2)

Created by Sanjay Sinha 11 Storage classes : Any data name occupies some space in the main memory to hold the data , when this storage space will be allocated to a data is decided depending on the storage class of the data . The types are : 1. Automatic ( Default )-- can be abbreviated as AUTO 2. Static 3. Based 4. Controlled --- can be abbreviated as CTL Based : The address is delimited by a pointer variable. E.g. DCL P POINTER; DCL A(100) FIXED BASED(P);

Created by Sanjay Sinha 12 Address can be assigned in any of the following ways: 1. By assigning the value returned by the ADDR built-in function. 2. By assigning the value of another pointer. 3. With the SET option of a READ statement. 4. With the SET option of a LOCATE statement. Controlled : Similar to based , in this programmer has a greater degree of control in the allocation of storage than he does for STATIC or AUTOMATIC. DCL A(100) INIT( (100) 0) CONTROLLED ;

Created by Sanjay Sinha 13 Partially declared identifiers : 1. The base : DCL A DECIMAL ; DCL B BINARY; 2. The scale : DCL C FIXED; DCL D FLOAT; 3. The base and precision : DCL AA DECIMAL(16); DCL BB BINARY(53); 4. The scale and precision : DCL CC FIXED(9,2) ; DCL DD FLOAT(16);

Created by Sanjay Sinha 14 List-directed Input: GET LIST (A,B,C,D); GET LIST (A,B,C,D) COPY; List-directed Output: The default line size for a PUT LIST is 120 positions. Different tab positions on the screen are : column no 1,25,49,73,97,121( only be used to print a record having length more than 120 characters). Different data items are printed beginning at predetermined tab positions.

Created by Sanjay Sinha 15 PUT LIST (A,B,C,D); PUT LIST (50,’abc’,123.445); To print at a specified tab position ,i.e. without preceding the previous position , specify a character-string of a blank to the preceding tab positions. E.g. PUT LIST (50,’ ‘,’abc’,’ ‘,123.445);--- First value will be printed at col no 1, second value at 49th col. , third value at 97th col , a blank will be printed at both 25th and 73rd col positions.

Created by Sanjay Sinha 16 Whenever PUT LIST statement is executed for the first time , it automatically skips to a new page ,if you want to print different values in different lines or pages , SKIP and PAGE options can be used. PAGE is used to advance to the top of a new page. SKIP is used to advance by a number of lines specified . If the no. of line is not specified , then assumed as SKIP(1). E.g. PUT PAGE LIST (‘ABC’); PUT SKIP LIST (1212); PUT SKIP(2) LIST(343);

Created by Sanjay Sinha 17 A skip(0) causes a suppression of the line feed. E.g. PUT PAGE LIST (‘ SALES REPORT’); PUT SKIP(0) LIST ((12)’_’) ; To specify the line number : e.g. PUT PAGE LINE(10) LIST(A,B,C); ----------------------------------------------------------------- PUT PAGE; PUT SKIP(2); PUT LINE(10) ;

Created by Sanjay Sinha 18 The Assignment Statement : e.g.TOTAL_COST = COST * QUANTITY; A,B,C = 0; The Arithmetic Operations : There are five basic arithmetic operators : Symbol Operations 1. ** Exponentiation 2. * Multiplication 3. / Division 4. + Addition 5. - Subtraction

Created by Sanjay Sinha 19 Concatenation : The || symbol is used is to join string or Bit data. e.g. NAME1 = ‘IIS’; NAME2 = ‘INFOTECH’ COMPANY_NAME = NAME1 || NAME2; DATA1 = ‘1100’B; DATA2 = ‘0011’B; DATA3 = DATA1 || DATA2 ; ----This will store ‘11000011’B in DATA3.

Created by Sanjay Sinha 20 Built-in Functions : The following are the classes of Built-in functions : 1. Arithmetic function 2. Mathematical function 3. Array-handling function 4. String handling 5. Condition handling 6. Storage control 7. Miscellaneous

Created by Sanjay Sinha 21 Arithmetic function : ABS(-44) --- 44 CEIL(3.333) --- 4 FLOOR(3.333) ---- 3 MIN(2,6,4) ---- 2 MAX(2,6,4) ---- 6 TRUNC(3.33) --- 3.00 SIGN(-4) --- -1 SIGN(0) ---- 0 SIGN(4) --- 1

Created by Sanjay Sinha 22 ROUND(123.456,1) --- 123.500 ROUND(123.456,2) --- 123.460 ROUND(123.456,0) ---- 123.000 ROUND(123.456,-1) ---- 120.000 ROUND(123.456,-2) ---- 100.000 ROUND(123.456,-3) ---- 0 MOD (25,6) --- 1 Mathematical function SIN , COS , TAN , LOG , LOG10 , SQRT

Created by Sanjay Sinha 23 String handling SUBSTR(‘IIS INFOTECH’,5,4) --- INFO A CHAR(10) --- A = ‘ 10’ LENGTH(A) -- 3 REPEAT(‘A’,2) --- ‘AA’ TRANSLATE ( ‘CAT’,’C’,’B’) --- ‘BAT’ Miscellaneous DATE returns date in the form of YYMMDD. TIME returns current time in the form of HHMMSSTTT. When these functions are used they should be explicitly declared as BUILTIN .

Created by Sanjay Sinha 24 UNSPEC ( identifier ) - Converts any identifier to a BIT string. DCL A CHAR(2) INIT(‘AB’); PUT LIST (UNSPEC(A)); --- prints the binary equivalent of ‘AB’ UNSPEC(A) = ‘0100000101000011’B; -- The value ‘AC’ will be assigned to the variable A

Created by Sanjay Sinha 25 An example for Pseudo-variable: BLANK : PROC OPTIONS(MAIN); DCL NAME CHAR(15) INIT('NOW IS THE TIME'); DCL NAME1 CHAR(12) VARYING; DCL I FIXED BINARY(15); DCL J FIXED BIN(15) INIT(1); DO I =1 TO LENGTH(NAME); IF SUBSTR(NAME,I,1)=' ' THEN; ELSE DO;

Created by Sanjay Sinha 26 SUBSTR(NAME1,J,1)=SUBSTR(NAME,I,1); J=J+1; END; END; PUT LIST(NAME1); END BLANK;

Created by Sanjay Sinha 27 Data Conversion: When mixed data types appear in an arithmetic expression , data items are converted to the data format of the other. DECIMAL is converted to BINARY. FIXED is converted to FLOAT. BIT is converted to CHARACTER A zero bit becomes a character 0. Arithmetic to CHARACTER( length should be > 2 bytes) CHARACTER to arithmetic Arithmetic( without symbol) to BIT BIT( always unsigned ) to arithmetic CHARACTER to BIT

Created by Sanjay Sinha 28 Selection Construct (Logical testing) : IF statement : The list of comparison operators .. Symbols used are GE or >= , GT or > , NE , ~= ,LT or < , LE or <= , NL , NG . The list of Logical operators …. Symbols used are ~ or ^ , & , | . IF condition1 THEN DO ………….; ………………; ………………; END; IF A=B THEN IF A=C THEN X=1; ELSE; ELSE X=3;

Created by Sanjay Sinha 29 The SELECT statement : -----------------Format- 1------------------------------------- SELECT ( identifier) ; WHEN( value1) statement; WHEN( value2) statement; OTHERWISE statement ; END; -----------------Format - 2 ---------------------------------- SELECT ; WHEN( cond1) statement; WHEN( cond2) statement; OTHERWISE statement ; END;

Created by Sanjay Sinha 30 The Comparison and Logical operators in the Assignment statement e.g. A=B=C; A=B>C; A= B>C & D>E; A=B>C | D>E;

Created by Sanjay Sinha 31 Conditions and On-units During the execution of a PL/I program , a number of conditions could arise causing a program to interrupt.It may be the detection of an unexpected error or of an occurrence that is expected but at an unpredictable time. Some conditions may be raised during file handling : ! ENDFILE (filename) - ENDPAGE( filename) ! RECORD(filename) - TRANSMIT(filename) They will be discussed during file handling only.

Created by Sanjay Sinha 32 Some conditions may be raised during arithmetic operations : ! CONVERSION( default is enabled ) e.g. DCL X BIT(4); X= ‘10A1’; ! SIZE (default is disabled) e.g. DCL A FIXED DEC(4); DCL B FIXED DEC(5) INIT(12345) ; A=B;

Created by Sanjay Sinha 33 ! FIXEDOVERFLOW( for fixed-point variables, default is enabled) e.g. DCL A FIXED DEC(5); DCL B FIXED DEC(5); DCL C FIXED DEC(5); A=99999; B=88888; C=A * B; ! OVERFLOW ( for floating-point variables, default is enabled) e.g. A = 55E71; B = 23E11; C=A*B;

Created by Sanjay Sinha 34 ! UNDERFLOW ( for floating-point variables, default is enabled) e.g. A = 55E-71; B = 23E-11; C=A*B; ! ZERODIVIDE( default is enabled) e.g. A=10; B=0; C=A/B;

Created by Sanjay Sinha 35 ! CHECK (used for debugging, default is disabled) (CHECK): AVERAGE:PROC OPTIONS(MAIN); : GET LIST(A,B,C); AVG=(A+B)/2; PUT LIST(‘THE AVERAGE IS’, AVG); END AVERAGE; ---- (CHECK(A,B)): --- (CHECK):AVG=(A+B)/2;

Created by Sanjay Sinha 36 The status of Conditions : Conditions are enabled or disabled through a condition prefix , which is the name of one or more conditions separated by commas, enclosed in parentheses, and prefixed to a statement by a colon. The word NO preceding the condition name indicates that the condition is to be disabled. E.g. (NOFIXEDOVERFLOW):SUM=A+B+C; (SIZE,NOFIXEDOVERFLOW):PROG1:PROC OPTIONS(MAIN); (NOSIZE):Y=A*B/C;

Created by Sanjay Sinha 37 /* An example of On - unit (SIZE) and pseudo-variable (SIZE): THIRD : PROCEDURE OPTIONS(MAIN); DCL NAME CHAR(10) VARYING , I FIXED BIN(15), A CHAR(1), BITVAR BIT(8); GET LIST(NAME); DO I = 1 TO LENGTH(NAME); A = SUBSTR(NAME,I,1); UNSPEC(A) = UNSPEC(A) | '00100000'B;

Created by Sanjay Sinha 38 PUT SKIP LIST (UNSPEC(A)); SUBSTR(NAME,I,1) = A; END ; PUT LIST (NAME); END THIRD;

Created by Sanjay Sinha 39 Changing the action taken : ON statement is used to specify what action will be taken if the condition arises.In the absence of a program-supplied ON statement for an enabled condition , standard system action will be taken. If , after having supplied your own on- unit for a condition , you wish to return to the standard system action for that on-unit, simply specify another ON statement with the keyword SYSTEM.For multiple lines of actions enclose the commands within BEGIN; …. END;

Created by Sanjay Sinha 40 ON ERROR BEGIN; ON ERROR SYSTEM; : : SNAP ERROR END; Null action: ON ENDPAGE ; First time the error is encountered the first ON ERROR will be executed and after entering the BEGIN block , if it encounters another error then it will not execute the first one , but the second one i.e. system will handle the condition in the default way. SNAP ERROR is used to execute the first ON ERROR even after the first time execution instead of second one.

Created by Sanjay Sinha 41 Simulating conditions : Can simulate execution of any specified ON condition statement by : SIGNAL condition_name ; If the specified condition is not enabled , then it’ll be taken as null statement; One of the uses of this statement is in program checkout to test the action of an on-unit and to determine that the correct program action is associated with the condition.

Created by Sanjay Sinha 42 BUILT-IN FUNCTIONS FOR ON-UNITS 1. ONCODE : e.g. ON ERROR PUT LIST(ONCODE); 2. ONLOC : e.g. MAIN: PROC OPTIONS(MAIN); : SUBRT:PROC; : : END SUBRT; END MAIN; 3. ONCHAR : e.g. CHAR=ONCHAR; 4. ONSOURCE : e.g. SOURCE=ONSOURCE;

Created by Sanjay Sinha 43 Iteration Constructs : 1. Label_name : DO WHILE( condition); : : END label_name; 2. DO UNTIL(condition); : : END; 3. DO I=n to m BY [+/-] x ; 4. DO M=1 TO 10,21 TO 30, 41 TO 50;

Created by Sanjay Sinha 44 5. DO K= 1 TO 5, 8 TO 18 BY 2 , 50 TO 55 BY 5, 40 TO 44; 6. DO J=3,12,6,5,45 7. DO I=n BY x; : : END; /* some other condition must be mentioned to come out of the loop , otherwise it’ll be an infinite loop or FIXEDOVERFLOW will occur.*/ 8. DO K=1 TO 10 WHILE ( A>10);

Created by Sanjay Sinha 45 9. DO K=1 TO 10,11 WHILE ( A>10); 10. DO K=1 TO 10,11 BY 0 WHILE ( A>10); 11. DO K=1 TO 10 UNTIL ( A>10); 12. DO NAME = ‘AAA’,’BBB’,’CCC’; Nested DO-groups : DO I=n TO M; DO J= x TO y; : : END; END;

Created by Sanjay Sinha 46 Leaving a loop : 1. By assigning a greater value than the highest value to the index variable 2. By GOTO statement which is not advised by structured programming. 3. By LEAVE statement . E.g. LEAVE block_name ; -- comes out from the specified block LEAVE ; -- comes out from the current block

Created by Sanjay Sinha 47 Array handling : e.g. DCL DAY_NAMES(7) CHAR(10); DCL LIST(-2:3) FIXED BIN(15,0) INIT(10,20,15,25,30,40); DCL TABLE(6,2) FIXED DEC (5); DCL TABLE(-2:3,4:5) FIXED DEC(5) INIT (0); -- only possible in Mainframe DCL B(5,3) FIXED INIT ( (15)0); DCL B(9,9) FIXED INIT ((81)-1); DCL A(2,2) FIXED INIT(1,2,3,4); DCL TABLE(10) CHAR(2) INIT((2)’A’); -- only possible in Mainframe DCL TABLE(10) CHAR(2) INIT((2) (2)’A’);

Created by Sanjay Sinha 48 DCL TABLE(10) CHAR(5) INIT((10) (1)’ABC’); DCL A(3) INIT(10,*,30); Array assignments: Scalar to Array : DCL MONTHS(12) FIXED(4,1); MONTHS=0; MONHS(5)=10.5; Array to Array : DCL A(5,5) ,B(5,5); A=B;

Created by Sanjay Sinha 49 Array Expressions: Prefix operators and Arrays: 1) A=-A; Infix operators and Arrays: 1) B=A*5 ; --Every elements of A is multiplied by 5 and stored in B. 2) A=A * A(1,2); -- Multiplies every elements by the value of the element at (1,2) and stores the data into A. 3) C=A +B;

Created by Sanjay Sinha 50 On conditions using String : 1. STRINGRANGE condition(default is disabled) 2. STRINGSIZE condition (default is enabled) On conditions using Array : 1.SUBSCRIPTRANGE condition(default is disabled)

Created by Sanjay Sinha 51 Array cross-sections: B(*,3) ; B(5,*); B(*,*) i.e. B ; e.g. S=SUM(B(*,3)) An example on Matrix multiplication : C=0; DO I=1 TO L; DO J=1 TO N; DO K=1 TO M; C(I,J)= A(I,K) * B(K,J) +C(I,J); END; END; END;

Created by Sanjay Sinha 52 An example on Matrix multiplication using cross sections : C=0; DO I=1 TO L; DO J=1 TO N; C(I,J)= SUM(A(I,*) * B(*,J)); END; END;

Created by Sanjay Sinha 53 /* An example using array */ REVERS:PROC OPTIONS(MAIN); DCL STR1(10) FIXED (10) INIT(1,2,3,4,5,6,7,8,9,10); DCL STR2(10) FIXED (10) ; DCL I FIXED (15); DCL J FIXED (15) INIT(1); DO I =10 TO 1 BY -1 ; STR2(J)=STR1(I); J=J+1; END; PUT LIST(STR2); END REVERS;

Created by Sanjay Sinha 54 /* An example to sort data stored in an array */ SORT1 : PROC OPTIONS (MAIN); DCL ARRAY1(10) FIXED (10); DCL I FIXED(2), J FIXED(2), TEMP FIXED(2); PUT LIST ('ENTER 10 NUMBERS'); DO I = 1 TO 10; PUT SKIP LIST ( 'ENTER NO. ',I); GET (ARRAY1(I)); END; DO I = 1 TO 9; DO J = I+1 TO 10;

Created by Sanjay Sinha 55 IF (ARRAY1(I) > ARRAY1(J) THEN DO; TEMP = ARRAY1(I); ARRAY1(I) = ARRAY1(J); ARRAY1(J) = TEMP; END; END; END; DO I = 1 TO 10; PUT (ARRAY1(I)); END; END SORT1;

Created by Sanjay Sinha 56 /* An example to handle two arrays */ STARR:PROC OPTIONS(MAIN); DCL 1 HISTORY (2), 2 NAME CHAR(20) , 2 GRADE FIXED(4,1); DCL 1 HONOR_STUDENT(2), 2 NAME CHAR(20) , 2 GRADE FIXED(4,1); DCL I FIXED DEC(1) INIT(1); PUT LIST('ENTER DATA OF STUDENTS:');

Created by Sanjay Sinha 57 DO I=1 TO 2; PUT SKIP LIST('ENTER NAME'); GET LIST(HISTORY(I).NAME); PUT SKIP LIST('ENTER GRADE'); GET LIST(HISTORY(I).GRADE); END; DO I=1 TO 2; IF HISTORY(I).GRADE>=92.5 THEN DO; HONOR_STUDENT(I).NAME =HISTORY(I).NAME; HONOR_STUDENT(I).GRADE = HISTORY(I).GRADE;

Created by Sanjay Sinha 58 END; END; DO I=1 TO 2; PUT SKIP LIST('NAME IS'); PUT LIST(HONOR_STUDENT(I).NAME); PUT SKIP LIST('GRADE IS'); PUT LIST(HONOR_STUDENT(I).GRADE); END; END STARR;

Created by Sanjay Sinha 59 Controlled storage with array bounds determined dynamically : CONTR : PROC OPTIONS(MAIN); DCL ( A(*,*),B(*,*),C(*,*)) CONTROLLED; GET LIST(I,J); ALLOCATE A(I,J),B(I,J); GET LIST(A,B); CALL ADDAR(A,B,C); PUT LIST(C); ADDAR : PROC(R,S,T); DCL (R(*,*),S(*,*) ,T(*)) CONTROLLED; ALLOCATE T(LBOUND(R,1) : HBOUND(R,1)); L1: DO K=LBOUND(R,1) TO HBOUND(R,1); T(K)=0;

Created by Sanjay Sinha 60 L2 : DO I=LBOUND(R,2) TO HBOUND(R,2); T(K)=R(K,J) + S(K,J) + T(K); END L2; END L1; FREE R,S; END ADDAR; END CONTR; /* Note : C can be passed as an argument although it has not yet been allocated. */

Created by Sanjay Sinha 61 Array manipulation and built-in functions : The DIM built-in The LBOUND built-in The HBOUND built-in The SUM built-in The PROD built-in

Created by Sanjay Sinha 62 I/O operations and Arrays : e.g. DCL AMOUNT(5) FIXED DEC(3); GET LIST(AMOUNT); e.g. DCL TABLE(6,2) FIXED DEC(3); GET LIST (TABLE); The Repetitive specification of a data item : e.g.DCL DAY_NAMES(7) CHAR(10); GET LIST( (DAY_NAMES(I) DO I=1 TO 7) ); e.g.DCL TABLE(6,2) FIXED DEC (5); GET LIST ((( TABLE(I,J) DO I=1 TO 6) DO J=1 TO 2)); e.g. GET LIST((A(I) DO I=1TO 5),(B(J),C(J) DO J=1 TO 3));

Created by Sanjay Sinha 63 Structures : DCL 1 EMP_DET, 2 EMP_NO FIXED DEC(5) , 2 EMP_NAME CHAR(20), 2 EMP_SALARY, 3 BASIC FIXED (9,2), 3 INDIA_ALLOW FIXED(9,2), 3 MEDICAL(12), 4 MED_MONTH FIXED(9,2); The statement could be written in a continuous string also.

Created by Sanjay Sinha 64 Array of Structures : DCL 1 EMP_DET(100), 2 EMP_NO FIXED DEC(5) , 2 EMP_NAME CHAR(20), 2 EMP_SALARY, 3 BASIC FIXED (9,2), 3 INDIA_ALLOW FIXED(9,2), 3 MEDICAL(12), 4 MED_MONTH FIXED(9,2); If attribute are to be explicitly declared in a structure, they may only be specified for elementary items.

Created by Sanjay Sinha 65 e.g. DCL EMP_DET1 CHAR(100); EMP_DET1=EMP_DET; ---- ERROR e.g. DCL EMP_DET1 LIKE EMP_DET; --it’ll copy the structure of EMP_DET to EMP_DET1. e.g. EMP_DET1=EMP_DET , BY NAME ; -- it’ll only copy the elements having the same names. e.g. EMP_DET1=‘ ‘; -- it’ll assign the same space to all character elements. Overlay defining: e.g. DCL EMP_DET2(100) DEFINED EMP_DET;

Created by Sanjay Sinha 66 Built-in Functions for structures : STRING function : It concatenates all the elements in an array or a structure into a single character or bit-string element .Thus, if it is desired to concatenate a number of elementary items found in a structure or array , it would be easier to code the STRING function than to code the concatenation operation a number of times. STRING may also be used as a pseudo- variable.

Created by Sanjay Sinha 67 E.g. DCL 1 EMP_DET, 2 EMP_NO CHAR(2) INIT(‘11’), 2 EMP_NAME CHAR(20) INIT(‘ JOAN K. HUGHES’), 2 EMP_ADD CHAR(30) INIT(‘JOHN WILEY & SONS ,ENGLAND’); DCL ITEM CHAR(45); ITEM=EMP_DET; --illegal ITEM=STRING(EMP_DET); EMP_DET=ITEM; STRING(EMP_DET)=ITEM;

Created by Sanjay Sinha 68 Pictures : The pictures are used for the following purposes : 1.To treat character-strings as arithmetic quantities. 2. To treat arithmetic quantities as character-strings. 3. To edit data 4. To validate data The general form of pictures for editing and validating is : PICTURE ‘picture specification characters’ There are two types of pictures : 1. Decimal pictures 2. Characters-string pictures

Created by Sanjay Sinha 69 Decimal pictures : The base and scale are implicitly DECIMAL and FIXED respectively. e.g DCL A PICTURE ‘9999V99’; DCL B PICTURE ‘(4)9V9(2); DCL C PICTURE ‘S9999V99; DCL D PIC ‘999S’; Editing data for printed output : Using Z , . , B, /, $, S, +, -, *,CR, DR AND , . E.g. DCL A PIC’****$S9,999V.99CR’; A=1234.54; PUT LIST(A); ------ The output is : *1234.54

Created by Sanjay Sinha 70 Character-string pictures : The symbols used are : A, X, 9 . E.g. DCL NAME PIC ’(20)A’; DCL ADDRESS PIC ‘(20)X; DCL PINCODE PIC ‘999999’; Pictures in Stream I/O : Some editing of data in stream I/O is automatic.In list-directed and data-directed output of arithmetic coded data , leading zeros will be suppressed and minus sign and decimal point inserted if necessary.

Created by Sanjay Sinha 71 Full editing capability may be achieved in list- directed output by simply assigning data items to identifiers that have the PICTURE attribute and then issuing a PUT LIST on those identifiers.In edit-directed I/O, full editing of data may be implemented by using a format item called P-format , containing any character allowed in PICTURE and used to describe the characteristics of external data. E.g. DCL VALUE FIXED DEC(8,2); DCL EDIT_DATA PIC’$$$$.$$$V.99CR’; VALUE=A*B;

Created by Sanjay Sinha 72 P’picture specification’ : e.g. GET FILE(SYSIN) EDIT(A,B,C,D) (COL(1) , P’ZZZ9’, P’99V99’,P’AA999’,P’(5)9); e.g. DCL ASSETS FIXED DEC(11,2); ASSETS = 45326985.76; PUT EDIT (ASSETS) (P’$$$$,$$$,$$$V.99’); The output is : b$45,326,985.76

Created by Sanjay Sinha 73 e.g. ASSETS=2500.00; PUT EDIT(ASSETS) (P’$ZZ,ZZZ,ZZZV.99’); The output is : $bbbbb2,500.00 e.g. DCL TODAY CHAR(6); TODAY=‘080880’; PUT EDIT(TODAY)(P’99/99/99’); The output is 08/08/80

Created by Sanjay Sinha 74 Procedures: Sub-routine procedures : 1. Invoked by CALL statement 2. Separately compiled ,from the invoking procedures, called as external procedures . 3. The length of these procedures’ names is limited to 7 or 8 characters. 4. A STOP or EXIT statement in both separately compiled procedure and nested sub-routine procedure , abnormally terminates execution of that sub-routine and of the entire program associated with the procedure that invoked it.

Created by Sanjay Sinha 75 5. Ideally an external sub-routine should not terminate the entire program , should return an error indicator to the calling program indicating whether or not an error has been detected during the execution of the sub-routine. It’s the function of MAIN program to decide what action is taken. 6. Arguments passed to a called procedure must be accepted by parameters of the calling procedure. 7. A built-in functions may be specified as arguments to other subprogram , that function is

Created by Sanjay Sinha 76 may be executed before the subroutine is called and the value is being passed when there is no argument of that built-in or the name of the built-in is enclosed by parentheses or the built-in is passed to another built-in as an argument. Otherwise the name is passed to the sub-routine. 8. If arguments and parameters are of same type, then the parameters share the same memory area of that of parameters , called as call by reference. 9. If arguments and parameters are of different types or constants , then the different memory area is allocated to the parameters , called as call by value.

Created by Sanjay Sinha 77 Dummy arguments :There are created in the following cases: 1) If an argument is a constant 2) If an argument is an expression involving operators. 3) If an argument is an expression in parentheses. 4) If an argument is a variable whose attributes are different from the attributes declared for the parameter in an entry name attribute specification appearing in the invoking block. 5) If an argument is itself a function reference containing arguments.

Created by Sanjay Sinha 78 The ENTRY attribute :It directs the compiler( in Mainframe only) to generate the coding to convert one or more arguments to conform to the attribute of the corresponding parameters .Declare the sub-routine within the main procedure as: DCL SUBRT ENTRY(types of parameters); After conversion , the values are stored in dummy arguments in different locations and names are automatically assigned by compiler, which can not be accessed by programmers.Any manipulation done by the called procedure only effects those dummy arguments and hence original arguments remain unchanged.

Created by Sanjay Sinha 79 /* An example of Sub-routine using ENTRY( CALL BY VALUE)*/ SUBPR : PROC OPTIONS(MAIN); DCL A FIXED BINARY(15) INIT(10), B FIXED BINARY (15) INIT(15), C FIXED BINARY(15); DCL ADDP ENTRY ( FIXED DEC(15), FIXED DEC(15), ); CALL ADDP(A,B,C); PUT LIST(C); ADDP : PROC(A,B,C); DCL A FIXED DEC(15), B FIXED DEC(15), C FIXED BIN(15); C=A+B; END ADDP; END SUBPR;

Created by Sanjay Sinha 80 The External attribute: Specifies a name to be known to other procedures containing an EXTERNAL declaration of the same name( must be limited to 6 characters). PROG: PROC OPTIONS(MAIN); DCL ARRAY(200) FIXED EXTERNAL; DCL SUM FIXED(7) EXTERNAL; GET LIST(ARRAY); CALL ADDSUM; PUT LIST(‘RESULT IS’,SUM);

Created by Sanjay Sinha 81 ADDSUM : PROC; DCL ARRAY(200) FIXED EXTERNAL; DCL SUM FIXED(7) EXTERNAL; SUM=0; DO K=1 TO 200 SUM=SUM+ARRAY(K); END; END ADDSUM; END PROG;

Created by Sanjay Sinha 82 /* An example of Sub-routine using builtin */ TIMED: PROC OPTIONS(MAIN); DCL TIME BUILTIN; DCL TSTR CHAR(8) ; CALL CTIME ((TIME),TSTR); PUT LIST (TSTR); CTIME:PROC(T,X) ; DCL T CHAR(9); DCL X CHAR(8); DCL A CHAR(2);

Created by Sanjay Sinha 83 DCL B CHAR(2); DCL C CHAR(2); A=SUBSTR(T,1,2); B=SUBSTR(T,3,2); C=SUBSTR(T,5,2); X=A || ':’ || B || ':’ ||C; END CTIME; END TIMED;

Created by Sanjay Sinha 84 Function Procedures: 1. A function is a procedure that returns a single value to the invoking procedure. 2. Invoked in the same manner as PL/I built-in functions are referenced. 3. Should not be invoked by CALL statement. 4. The RETURN statement is used to terminate a function and a single value to the point of invocation. CALC:PROCEDURE(A,B,C); RETURN(A+B+C); END CALC;

Created by Sanjay Sinha 85 5. By default , if the function name begins with the letters A to H or O to Z , then the result will be DECIMAL FLOAT(6). Names starting with I to N return a result with the attributes FIXED BINARY (15). D=CALC(A,B,C); To return data of some other type , use RETURNS keyword , in both invoking and invoked procedures.

Created by Sanjay Sinha 86 CALC:PROCEDURE(A,B,C) RETURNS(FIXED DECIMAL(7)); RETURN(A+B+C); END CALC; 6. The RETURNS keyword , when specified in a PROCEDURE or ENTRY statement , is referred to as the RETURNS option.In the previous example , the invoking procedure must also specify that CALC is returning a FIXED DECIMAL value of the same precision because these attributes differ from the default.

Created by Sanjay Sinha 87 The RETURNS attribute , specified in a DECLARE statement for an entry name , indicates the attributes of the value returned by that function. MAIN: PROCEDURE OPTION(MAIN); DCL CALC ENTRY RETURNS (FIXED DEC(7)); DCL SUM FIXED DEC(7); GET LIST (A,B,C); SUM=CALC(A,B,C); : : END MAIN;

Created by Sanjay Sinha 88 /* An example of Function */ SUBPR : PROC OPTIONS(MAIN); DCL A FIXED BINARY(15) INIT(10), B FIXED BINARY (15) INIT(15), C FIXED BINARY(15); C= ADDP(A,B); PUT LIST(C); ADDP : PROC(A,B) RETURNS(FIXED BIN(15)); C=A+B; RETURN (C); END ADDP; END SUBPR;

Created by Sanjay Sinha 89 /* An example of function using builtin */ TIMED: PROC OPTIONS(MAIN); DCL TIME BUILTIN; DCL TRES CHAR(8) ; TRES= CTIME (TIME); PUT LIST (TRES); CTIME:PROC(T,X) RETURNS(CHAR(8)); DCL T CHAR(9); DCL X CHAR(8); DCL A CHAR(2); DCL B CHAR(2);

Created by Sanjay Sinha 90 DCL C CHAR(2); A=SUBSTR(T,1,2); B=SUBSTR(T,3,2); C=SUBSTR(T,5,2); X=A || ':’ || B || ':’ ||C; RETURN(X); END CTIME; END TIMED;

Created by Sanjay Sinha 91 Recursive procedures : When a procedure invokes itself , its said to be recursive. e.g. the computation of factorial where n! = 1*2*3…….*n ----code in the calling procedure-------- N=4; RESULT=CALC_FACT(N); -----code in the called procedure --------- CALC_FACT:PROCEDURE(M); K=1;

Created by Sanjay Sinha 92 DO I=1 TO M; K=K*I; END; RETURN(K); END CALC_FACT; -----code using RECURSIVE option----------- CALC_FACT:PROCEDURE(M) RECURSIVE; K=M - 1; IF K=1 THEN I=M; ELSE I=M * CALC_FACT(K); RETURN(I); END CALC_FACT;

Created by Sanjay Sinha 93 File declarations : 1. Define the file via a DECLARE statement. -- DECLARE EMPLOYEE FILE(other attributes); Attributes associated with a file include the type of transmission ( STREAM or RECORD) , the direction of transmission (INPUT ,OUTPUT , UPDATE in the case of disk files ) and the physical environment of the file e.g. ENV / ENVIRONMENT to specify BLKSIZE or RECSIZE or record type( F,V,VB,FB) or device type.

Created by Sanjay Sinha 94 ---- DECLARE EMPLOYEE FILE INPUT STREAM ENV (options); 2. File must be opened before communicating via OPEN statement and can also provide additional file attributes at open time. File attributes : 1. FILE attribute 2. INPUT/OUTPUT attribute 3. STREAM attribute 4. ENVIRONMENT attribute 5. PRINT attribute

Created by Sanjay Sinha 95 The OPEN statement : Files are opened automatically , hence not required to give the command explicitly . But still used to specify the additional file attributes and/or options may be specified at open times. OPEN FILE(FILE1), FILE(FILE2); OPEN FILE(FILE1) PAGESIZE(50); OPEN FILE(FILE1) LINESIZE(121);

Created by Sanjay Sinha 96 3. Process information in the file via READ or WRITE or REWRITE or GET or PUT statements. Default of pre-defined files : When not mentioned in GET or PUT statement , SYSIN is for the standard input or SYSPRINT for the output file. E.g. GET LIST (A,B,C); --- is equivalent to GET FILE(SYSIN) LIST (A,B,C): 4. Close the file via CLOSE statement. CLOSE FILE (EMPLOYEE);

Created by Sanjay Sinha 97 In the initial design of PL/I , stream I/O was intended for scientific applications. Now-a- days stream I/O is used in both scientific and commercial programming applications , although the majority of commercial applications use record I/O . Stream I/O is most often used for a terminal or printer files , although it could also be used for tape or disk unblocked records in consecutive files.

Created by Sanjay Sinha 98 Stream I/O : All input and output data items are in the form of stream of characters. In input stream , characters are converted to the internal attributes of the identifiers specified in the GET statement. On output , coded arithmetic data items are automatically converted back to character form before the output takes place. There are three types : 1. List-directed I/O 2. Edit-directed I/O 3. Data-directed I/O

Created by Sanjay Sinha 99 Edit-directed I/O: 1. The format of the data items must be mentioned. 2. General format : GET EDIT (data list)(format list); PUT EDIT (data list)(format list); e.g. GET EDIT (EMP_NO , EMP_NAME, BASIC, INDIA_ALLOW, MED_MONTH ) (COLUMN(1), F(5) , A(20),F (9,2), F(9,2), F(9,2)); e.g. GET EDIT (EMP_NO , EMP_NAME, BASIC, INDIA_ALLOW, MED_MONTH ) (R(RFMT));

Created by Sanjay Sinha 100 : RFMT: FORMAT(COLUMN(1), F(5) , A(20),F (9,2), F(9,2), F(9,2)); Rules : a) All data list items have corresponding format items b) If there are more format than data items , there is a return to the beginning of the format list. E.g. GET EDIT(A,B,C) (F(4),F(5)); c) The data list item need not have the same width specification as the corresponding format items.

Created by Sanjay Sinha 101 E.g. DCL NAME CHAR(15); GET EDIT (NAME) (A(20)); d) I/O continues until the data list is exhausted. e) Input data items may be pseudo-variables e.g. DCL NAME CHAR(20); GET EDIT (SUBSTR(NAME,5,10)) (A(20)); f) Data list items may be names of data aggregates. E.g. DCL TABLE(10) FLOAT DEC(6); GET EDIT(TABLE) (COLUMN(1),F(6,2));

Created by Sanjay Sinha 102 Equivalent to : E.g. GET EDIT ((TABLE (I) DO I=1 TO 10)) (COLUMN(1),F(6,2)); E.g.DCL TABLE(2,5) FLOAT DEC(6); PUT EDIT (TABLE) (F(10)); Equivalent to: e.g. GET EDIT ( ( (TABLE(I,J) DO J=1 TO 5) DO I=1 TO 2) ) (F10));

Created by Sanjay Sinha 103 Equivalent to : DO I=1 TO 2; DO J=1 TO 5; GET EDIT (TABLE(I,J)) (F10)); END; END; g) Output data items may be built-in functions h) Output data items may be PL/I constant i) Data items may consists of Element Expression j) More than one data list and corresponding format list may be specified

Created by Sanjay Sinha 104 e.g. GET EDIT (data list1) (format list1) (data list2) (format list2) …; 3. A file name could also be specified : GET FILE(filename) EDIT (data list)(format list); PUT FILE(filename) EDIT (data list)(format list);

Created by Sanjay Sinha 105 Data-directed I/O: Data-directed Input: Each item in the input is in the form of an assignment that specifies both the value and the variable to which it is to be assigned. E.g. GET DATA (list of items); -- its optional and maxm 320 items can be mentioned. A=12.3, B=23, C=‘ABCDEF’,D=‘10101’B; GET DATA (C,B,A,D); GET DATA (A,B,C,D,E); --- E is not altered by the input operation.

Created by Sanjay Sinha 106 GET DATA (A,B); --- error as C,D are in the input stream but not in the data list. And raises the NAME condition. ON NAME (SYSIN) BEGIN; : : END; GET DATA; --the names in the stream may be any names known at the pint of the GET statement. A data list in the GET statement is optional ,because the semi-colon determines the number if items to be obtained from the stream.

Created by Sanjay Sinha 107 If the data includes the name of an array , subscripted references to the array may appear in the stream, although subscripted names cannot appear in the data list. The entire array need not appear in the stream , only those elements that actually appear in the stream will be assigned . E.g. DCL TABLE(10) FIXED (5,2); GET DATA (TABLE); the input stream consists of the following assignment statements: TABLE(3)=34.34; TABLE(10)=12.12;

Created by Sanjay Sinha 108 Data-directed output : Each data item is placed in the stream in the form of assignment statements separated by blanks. The last item output by each PUT statement followed by a semicolon.Fixed point binary and floating point binary data appear in fixed-point decimal format. DCL A FIXED DEC(5) INIT(0); DCL B FIXED DEC(5) INIT(0); DCL C FIXED BIN(5) INIT(170); PUT DATA(A,B,C); PUT PAGE DATA(A,B,C); PUT SKIP(3) DATA(A,B,C); PUT LINE(5) DATA (A,B,C);

Created by Sanjay Sinha 109 The output to the default file SYSPRINT in the format : A=0 B=0 C=170; If the output is to other than a printer , one blank is placed between each assignment statement. The data list may be an element , array , a subscripted name, structure or a repetitive specification involving any of these elements or further repetitive specification. PUT DATA; PUT PAGE DATA (‘SALES REPORT’); --error

Created by Sanjay Sinha 110 GET FILE (filename) DATA(A,B,C); Data to be entered as: : A=……, B=…… , C=……. PUT FILE(filename ) DATA(A,B,C); The COUNT Built-in function: DCL INFILE FILE INPUT STREAM; GET FILE (INFILE) DATA; I=COUNT(INFILE); /* no of elements is stored */ Output data item may be Built-in function: PUT EDIT (DATE)(P’99/99/99’);

Created by Sanjay Sinha 111 Example: ON ENDFILE (DATA) MORE_RECORDS=NO; MORE_RECORDS=YES; READ FILE(DATA) INTO(DATA_AREA); DO WHILE (MORE_RECORDS); WRITE FILE(PRINT_FILE) FROM (DATA_AREA); READ FILE(DATA) INTO(DATA_AREA); END;

Created by Sanjay Sinha 112 Conditions and On-Units : The ERROR condition is raised as a result of the standard system action and terminate the program and return control to the O.S. The ON statements are used to specify action to be taken when a specified condition causes a program to interrupt. E.g. ON condition on-unit; In absence of any of these On-Units specified in the program, system will raise ERROR condition.The following conditions are by default enabled , can not be disabled.

Created by Sanjay Sinha 113 1.ENDFILE(filename) 2. ENDPAGE(filename) 3. RECORD(filename) 4.TRANSMIT(filename) 5. CONVERSION 6. SIZE ON ENDFILE : This condition is raised during a GET or READ operation. ON ENDPAGE :This condition is raised when a PUT statement results in an attempt to start a new line beyond the limit specified for PAGESIZE( specified in OPEN statement).

Created by Sanjay Sinha 114 ON KEY condition : Raised during operations on keyed records in any of the following cases: 1. The keyed record can not be found for a READ or REWRITE statement. 2. An attempt is made to add a duplicate key by a WRITE statement. 3. The key has not been correctly specified. 4. No space is available to add the keyed record. E.g. ON KEY(FILE1) BEGIN; FLAG=YES;

Created by Sanjay Sinha 115 CODE=ONCODE; PUT SKIP EDIT(‘KEY ERROR FOR FILE1 , ONCODE IS’,CODE) (A); END; : : READ FILE(FILE1) INTO(DATA_AREA) KEY(PARTNO); IF FLAG THEN CALL ERR-ROUTINE; ELSE CALL UPDATE_ROUTINE;

Created by Sanjay Sinha 116 ON UNDEFINEDFILE condition : Raised whenever an attempt to open a file is unsuccessful. 1. A conflict in attributes exists. 2. Attributes are incomplete. ON RECORD condition : Raised during a READ,WRITE , REWRITE operation. The input operations it is raised by either of the following : 1. The size of the record on the data set is greater than the size of the variable into which the record is to be read ( for F,V,U format).

Created by Sanjay Sinha 117 2. The size of the record is less than the size of the variable ( for F format). For a WRITE or REWRITE operations: 1. When the size of the variable from which the record is to be written is greater than the maximum size specified for the record (F,V,U formats). 2. When the size of the variable is less than the size specified for the record ( F format). ON TRANSMIT condition :This condition is raised due to any hardware malfunction . It indicates that the data transmitted is incorrect.

Created by Sanjay Sinha 118 Built-In Functions : ONKEY : It extracts the value of the key for the record that caused an I/O condition to be raised. E.g. DCL KEY_ERRCHAR(9) VARYING; DCL ONKEY BUILTIN; ON KEY(FILE1) BEGIN; KEY_ERR=ONKEY; : : END;

Created by Sanjay Sinha 119 ONFILE : It determines the name of the file for which an I/O or CONVERSION condition was raised and returns that name to point of invocation. E.g. DCL NAM CHAR(3) VARYING; DCL ONFILEBUILTIN; ON KEY(FILE2) BEGIN; NAME=ONFILE; : : END;

Created by Sanjay Sinha 120 Record I/O : 1. Declare the file by DECLARE statement : e.g. DCL DATA FILE INPUT RECORD ENV (F RECSIZE (80) ); DCL PRINT_FILE OUTPUT RECORD ENV ( F RECSIZE (80) ); DCL DATA_AREA CHAR(80); 2. The keyword RECORD specifies the type of I/O . 3. The record I/O statements that are used to communicate with files include READ, WRITE, REWRITE and DELETE.

Created by Sanjay Sinha 121 Carriage control in Record I/O : 1. The program counter is automatically incremented as and when a WRITE command is used. 2. When program counter reaches the maximum line per page , the program gives the command to skip the page to the printer. 3. To accomplish the carriage control for record output , append an extra character to the beginning of each record. 4. A keyword must be added to the ENVIRONMET section of the file declaration to notify PL/I that

Created by Sanjay Sinha 122 these carriage control characters are being used in the program and that the I/O routines are to interpret the first character of each record accordingly. 5. Two different sets are CTLASA or CTL360 . 6. If CTLASA is used , the carriage control operation is performed before the printing , in case of CTL360 , after printing. 7. Generally CTL360 characters are faster than CTLASA.

Created by Sanjay Sinha 123 Example : LINECNT: PROC OPTIONS(MAIN); DCL DATAIN FILE INPUT RECORD ENV(F RECSIZE(80)); DCL FILE INPUT RECORD ENV (F RECSIZE(80)); DCL PRINT_FILE FILE OUTPUT RECORD ENV (F RECSIZE(81) CTLASA ); DCL DATA_AREA CHAR(80); DCL LCTR FIXED(3); DCL MORE_RECORDS BIT(1);

Created by Sanjay Sinha 124 DCL NO BIT(1); DCL PRINT_AREA CHAR(81); ON ENDFILE(DATAIN) MORE_RECORDS=NO; OPEN FILE(DATAIN), FILE(PRINT_FILE); LCTR=55; READ FILE(DATAIN) INTO(DATA_AREA); DO WHILE (MORE_RECORDS); LCTR=LCTR+1; IF LCTR>55 THEN DO;

Created by Sanjay Sinha 125 PRINT_AREA=‘1’ || DATA_AREA; LCTR=0; END; ELSE PRINT_AREA=‘ ‘ ||DATA_ARE; WRITE FILE(PRINT_FILE) FROM (PRINT_AREA); READ FILE(DATAIN) INTO(DATA_AREA); END;

Created by Sanjay Sinha 126 File Organization : 1. Types of file access are ,SEQUENTIAL and DIRECT. 2. Types of file organization are , CONSECUTIVE (sequential) , INDEXED( indexed sequential) , REGIONAL(direct or random) , VSAM( ESDS, KSDS, RRDS). 3.Different file attributes : a) FILE b) EXTERNAL/INTERNAL c) STREAM/RECORD d) INPUT/ OUTPUT/ UPDATE

Created by Sanjay Sinha 127 /*AN EXAMPLE TO CREATE AN INDEXED FILE FOR STUDENT DATA */ WRprogram : PROC OPTIONS(MAIN); DCL STUD FILE OUTPUT INDEXED RECORD; DCL 1 STUD_DATA, 2 STUD_ROLL FIXED BINARY(15), 2 STUD_NAME CHAR(20), 2 STUD_MARKS FIXED BIN(15); DCL CONT CHAR(1) INIT('Y');

Created by Sanjay Sinha 128 DO WHILE (CONT='Y'); PUT SKIP LIST ('ENTER DATA FOR STUDENT'); PUT SKIP LIST ('ENTER ROLL FOR STUDENT'); GET LIST (STUD_ROLL); PUT SKIP LIST ('ENTER NAME FOR STUDENT'); GET LIST(STUD_NAME); PUT SKIP LIST ('ENTER MARKS FOR STUDENT'); GET LIST (STUD_MARKS); WRITE FILE(STUD) FROM (STUD_DATA) KEYFROM(STUD_ROLL) ;

Created by Sanjay Sinha 129 PUT SKIP LIST ('WANT TO CONT(Y/N)?'); GET SKIP LIST (CONT); END; CLOSE FILE(STUD); END WRprogram;

Created by Sanjay Sinha 130 /* MENU PROGRAM TO CALL DIFF. PROGRAMS */ MENUprogram: PROC OPTIONS(MAIN); DCL RDprogram EXT ENTRY; DCL WRprogram EXT ENTRY; DCL MODprogram EXT ENTRY; DCL CH CHAR(1); PUT SKIP LIST (' MENU '); PUT SKIP LIST (' 1. TO ADD A RECORD'); PUT SKIP LIST (' 2. TO READ A RECORD'); PUT SKIP LIST (' 3. TO MODIFY A RECORD'); PUT SKIP LIST (' 4. EXIT ');

Created by Sanjay Sinha 131 PUT SKIP(2) LIST ('ENTER YOUR CHOICE(1-4):'); GET LIST(CH); IF CH='1’ THEN CALL WRprogram; ELSE IF CH='2' THEN CALL RDprogram; ELSE IF CH='3' THEN CALL MODprogram;

Created by Sanjay Sinha 132 ELSE IF CH='4' THEN RETURN; ELSE PUT LIST ('WRONG CHOICE'); END MENUprogram;

Created by Sanjay Sinha 133 /* TO CREATE A FILE FOR STUDENT DATA */ WRprogram : PROC ; DCL STUD FILE OUTPUT RECORD; DCL 1 STUD_DATA, 2 STUD_ROLL FIXED BINARY(15), 2 STUD_NAME CHAR(20), 2 STUD_MARKS FIXED BIN(15); /*OPEN FILE STUD OUTPUT;*/ DCL CONT CHAR(1) INIT('Y'); DO WHILE (CONT='Y'); PUT SKIP LIST ('ENTER DATA FOR STUDENT'); PUT SKIP LIST ('ENTER ROLL FOR STUDENT');

Created by Sanjay Sinha 134 GET LIST (STUD_ROLL); PUT SKIP LIST ('ENTER NAME FOR STUDENT'); GET LIST(STUD_NAME); PUT SKIP LIST ('ENTER MARKS FOR STUDENT'); GET LIST (STUD_MARKS); WRITE FILE(STUD) FROM (STUD_DATA) ; PUT SKIP LIST ('WANT TO CONT(Y/N)?'); GET SKIP LIST (CONT); END; CLOSE FILE(STUD); END WRprogram;

Created by Sanjay Sinha 135 /* TO MODIFY FILE FOR STUDENT DATA */ MODprogram : PROC ; DCL STUD FILE UPDATE RECORD; DCL 1 STUD_DATA, 2 STUD_ROLL FIXED BINARY(15), 2 STUD_NAME CHAR(20), 2 STUD_MARKS FIXED BIN(15); /*OPEN FILE STUD INPUT;*/ DCL RNO FIXED BINARY(15); DCL CONT CHAR(1) INIT('Y');

Created by Sanjay Sinha 136 ON ENDFILE(STUD) BEGIN; PUT SKIP LIST('RECORD NOT FOUND'); GO TO OUT; END; DO WHILE (CONT='Y'); PUT SKIP LIST('ENTER ROLL NO TO BE MODIFIED'); GET LIST(RNO); READ FILE(STUD) INTO (STUD_DATA) ; SEARCH : IF STUD_ROLL=RNO THEN BEGIN;

Created by Sanjay Sinha 137 PUT LIST ('ENTER NEW DATA'); PUT SKIP LIST ('ENTER NEW ROLL FOR STUDENT'); GET LIST (STUD_ROLL); PUT SKIP LIST ('ENTER NEW NAME FOR STUDENT'); GET LIST(STUD_NAME); PUT SKIP LIST ('ENTER NEW MARKS FOR STUDENT'); GET LIST (STUD_MARKS); REWRITE FILE(STUD) FROM (STUD_DATA) ; GO TO OUT;

Created by Sanjay Sinha 138 END; ELSE BEGIN; READ FILE(STUD) INTO (STUD_DATA) ; GOTO SEARCH; END; OUT: PUT SKIP LIST('WANT TO CONT(Y/N):'); GET LIST(CONT); END; CLOSE FILE(STUD); END MODprogram;

Created by Sanjay Sinha 139 /* TO READ FILE FOR STUDENT DATA */ RDprogram : PROC ; DCL STUD FILE INPUT RECORD; DCL 1 STUD_DATA, 2 STUD_ROLL FIXED BINARY(15), 2 STUD_NAME CHAR(20), 2 STUD_MARKS FIXED BIN(15); /*OPEN FILE STUD INPUT;*/ DCL FLAG CHAR(1) INIT('Y'); ON ENDFILE(STUD) FLAG='N'; PUT SKIP LIST('END OF FILE');

Created by Sanjay Sinha 140 READ FILE(STUD) INTO (STUD_DATA) ; DO WHILE (FLAG='Y'); PUT SKIP LIST(STUD_ROLL); PUT SKIP LIST(STUD_NAME); PUT SKIP LIST(STUD_MARKS); READ FILE(STDATA) INTO (STUD_DATA) ; END; CLOSE FILE(STUD); END RDprogram;

Introduction to IBM PL/1 Programming Language

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