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Python Programming | JNTUK | UNIT 2 | Lecture 6 & 7 | Conditional & Control Statements
The document discusses various Python programming concepts including control statements, loops, strings, files and string manipulation. Control statements like if-else are used to conditionally execute code. Loops like for and while are used to repeatedly execute code while a condition is true. Strings can be manipulated using indexing, slicing and other string methods. Files can be read from and written to using file handling methods in Python.
Python Programming | JNTUK | UNIT 2 | Lecture 6 & 7 | Conditional & Control Statements
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- 2. UNIT 2 :SYLLABUS • Conditions, Boolean logic, logical operators; (Refer UNIT 1: Operators) • ranges • Control statements: if-else, loops (for, while); short-circuit (lazy) evaluation • Strings and text files; manipulating files and directories, os and sys modules; text files: reading/writing text and numbers from/to a file; creating and reading a formatted file (csv or tab-separated). • String manipulations: subscript operator, indexing, slicing a string; • strings and number system: converting strings to numbers and vice versa. Binary, octal, hexadecimal numbers
- 3. range function • Therange() function returns a sequence of numbers, starting from 0 by default, and increments by 1 (by default), and stops before a specified number • The range() function can be represented in three different ways, or you can think of them as three range parameters: 1. range(stop) 2. range(start, stop) 3. range(start, stop, step) • start: integer starting from which the sequence of integers is to be returned • stop: integer before which the sequence of integers is to be returned. The range of integers end at stop – 1. • step: integer value which determines the increment between each integer in the sequence
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- 5. Strings and textfiles Control statements strings and number system String manipulations
- 6. Conditional (if –else) Conditional execution Alternative execution Chained conditionals Nested conditionals • Conditions change the flow of program execution • if statement is used in conditions Syntax: if condition: statement 1 … • Two possibilities (else is used) Syntax: if condition: statement 1 … else: statement 2 … • More than two possibilities. • elif is used. Syntax: if condition: statement 1 elif condition: statement 2 elif condition: statement 3 else: statement 4 • Another Condition in one condition Syntax: if condition1: if condition2: statement 1 else: statement 2 else: statement 3 Control statements
- 7. Conditional (if –else) Control statements Conditional execution • Conditions change the flow of program execution • if statement is used in conditions Syntax: if condition: statement 1 …
- 8. Conditional (if –else) Control statements Conditional execution • Conditions change the flow of program execution • if statement is used in conditions Syntax: if condition: statement 1 …
- 9. Control statements Conditional execution Alternative execution Chained conditionals Nested conditionals • Conditions changethe flow of program execution • if statement is used in conditions Syntax: if condition: statement 1 … • Two possibilities (else is used) Syntax: if condition: statement 1 … else: statement 2 … • More than two possibilities. • elif is used. Syntax: if condition: statement 1 elif condition: statement 2 elif condition: statement 3 else: statement 4 • Another Condition in one condition Syntax: if condition1: if condition2: statement 1 else: statement 2 else: statement 3 Conditional (if – else)
- 10. Conditional (if –else) Control statements Alternative execution • Two possibilities (else is used) Syntax: if condition: statement 1 … else: statement 2 …
- 11. Conditional (if –else) Control statements Alternative execution • Two possibilities (else is used) Syntax: if condition: statement 1 … else: statement 2 …
- 12. Conditional (if –else) Control statements Conditional execution Alternative execution Chained conditionals Nested conditionals • Conditions change the flow of program execution • if statement is used in conditions Syntax: if condition: statement 1 … • Two possibilities (else is used) Syntax: if condition: statement 1 … else: statement 2 … • More than two possibilities. • elif is used. Syntax: if condition: statement 1 elif condition: statement 2 elif condition: statement 3 else: statement 4 • Another Condition in one condition Syntax: if condition1: if condition2: statement 1 else: statement 2 else: statement 3
- 13. Conditional (if –else) Control statements Chained conditionals • More than two possibilities. • elif is used. Syntax: if condition: statement 1 elif condition: statement 2 elif condition: statement 3 else: statement 4
- 14. Conditional (if –else) Control statements Chained conditionals • More than two possibilities. • elif is used. Syntax: if condition: statement 1 elif condition: statement 2 elif condition: statement 3 else: statement 4
- 15. Conditional (if –else) Control statements Conditional execution Alternative execution Chained conditionals Nested conditionals • Conditions change the flow of program execution • if statement is used in conditions Syntax: if condition: statement 1 … • Two possibilities (else is used) Syntax: if condition: statement 1 … else: statement 2 … • More than two possibilities. • elif is used. Syntax: if condition: statement 1 elif condition: statement 2 elif condition: statement 3 else: statement 4 • Another Condition in one condition Syntax: if condition1: if condition2: statement 1 else: statement 2 else: statement 3
- 16. Conditional (if –else) Control statements Nested conditionals • Another Condition in one condition Syntax: if condition1: if condition2: statement 1 else: statement 2 else: statement 3
- 17. Conditional (if –else) Control statements Nested conditionals • Another Condition in one condition Syntax: if condition1: if condition2: statement 1 else: statement 2 else: statement 3
- 18. Conditional (if –else) Control statements Conditional execution Alternative execution Chained conditionals Nested conditionals • Conditions change the flow of program execution • if statement is used in conditions Syntax: if condition: statement 1 … • Two possibilities (else is used) Syntax: if condition: statement 1 … else: statement 2 … • More than two possibilities. • elif is used. Syntax: if condition: statement 1 elif condition: statement 2 elif condition: statement 3 else: statement 4 • Another Condition in one condition Syntax: if condition1: if condition2: statement 1 else: statement 2 else: statement 3
- 19. Strings and textfiles Control statements strings and number system String manipulations
- 20. Loops (for ,while) Control statements • A loop is a programming structure that repeats a sequence of instructions until a specific condition is met. • Each repetition of the action is known as a pass or an iteration. • Two main loop statements are available. • for • while
- 21. Loops (for ,while) Control statements • for: Executes a sequence of statements multiple times and reduces the code that manages the loop variable.
- 22. Loops (for ,while) Control statements Loop Header end with colon (:) body must be indented
- 23. Loops (for ,while) Control statements
- 24. Loops (for ,while) Control statements Using else Statement with for Loop: • If the else statement is used with a for loop, the else statement is executed when the loop has exhausted iterating the list.
- 25. Loops (for ,while) Control statements • A while loop statement in Python programming language repeatedly executes a target statement if a given condition is true.
- 26. Loops (for ,while) Control statements
- 27. Loops (for ,while) Control statements
- 28. Loops (for ,while) Control statements Using else Statement with while Loop: • If the else statement is used with a while loop, the else statement is executed when the condition becomes false.
- 29. Loops (for ,while) Control statements Infinite Loop: • A loop becomes infinite loop if a condition never becomes FALSE. • When using while loops because of the possibility that this condition never resolves to a FALSE value. • This results in a loop that never ends. Such a loop is called an infinite loop.
- 30. Loops (for ,while) Control statements Loop Control Statements: • Loop control statements change execution from its normal sequence. • Python supports the following control statements. o break o continue o pass break: Terminates the loop statement and transfers execution to the statement immediately following the loop. continue: Causes the loop to skip the remainder of its body and immediately retest its condition prior to reiterating. pass: when a statement is required syntactically but you do not want any command or code to execute.
- 31. Loops (for ,while) Control statements break: Terminates the loop statement and transfers execution to the statement immediately following the loop. continue: Causes the loop to skip the remainder of its body and immediately retest its condition prior to reiterating. pass: when a statement is required syntactically but you do not want any command or code to execute.
- 32. Loops (for ,while) Control statements break: Terminates the loop statement and transfers execution to the statement immediately following the loop. continue: Causes the loop to skip the remainder of its body and immediately retest its condition prior to reiterating. pass: when a statement is required syntactically but you do not want any command or code to execute.
- 33. Loops (for ,while) Control statements break: Terminates the loop statement and transfers execution to the statement immediately following the loop. continue: Causes the loop to skip the remainder of its body and immediately retest its condition prior to reiterating. pass: when a statement is required syntactically but you do not want any command or code to execute.
- 34. Loops (for ,while) Control statements
- 35. Loops (for ,while) Control statements
- 36. Loops (for ,while) Control statements
- 37. Loops (for ,while) Control statements Nested Loop: • Python programming language allows to use one loop inside another loop.
- 38. Loops (for ,while) Control statements Nested Loop: • Python programming language allows to use one loop inside another loop.
- 39. Strings and textfiles Control statements strings and number system String manipulations
- 40. Short-Circuit Evaluation Control statements • ThePython virtual machine sometimes knows the value of a Boolean expression before it has evaluated all its operands. • For instance, in the expression A and B, if A is false, then so is the expression, and there is no need to evaluate B • Likewise, in the expression A or B, if A is true, then so is the expression, and again there is no need to evaluate B. • This approach, in which evaluation stops as soon as possible, is called short-circuit evaluation.
- 41. UNIT 2 :SYLLABUS • Conditions, Boolean logic, logical operators; (Refer UNIT 1: Operators) • ranges • Control statements: if-else, loops (for, while); short-circuit (lazy) evaluation • Strings and text files; manipulating files and directories, os and sys modules; text files: reading/writing text and numbers from/to a file; creating and reading a formatted file (csv or tab-separated). • String manipulations: subscript operator, indexing, slicing a string; • strings and number system: converting strings to numbers and vice versa. Binary, octal, hexadecimal numbers