C program to write c program without using main function

C program to write c program without using main function

• 1.
  C Program toWrite C Program Without using Main Function in 3 ways
• 2.
  Run C ProgramWithout Main Function Conceptually C Program is meaningless without main Function . Every Program Must have Main Function. Main Function : a] It is Entry Point of Every C Program. b] All Predefined and User-defined Functions are called directly or indirectly through the main. c] So C Program Must have Main Function. But I have decided not to write main and want to run C Program , How ? We have 3 approaches of Writing C Program without using main().
• 3.
  1 2 3 4 5 6 7 #include<stdio.h> #define begin main intbegin() { printf("Hello"); return (0); } Way 1 : Using #define Preprocessor Directive
• 4.
  Way 1 :Using #define Preprocessor Directive What Preprocessor is doing Here ? • Save C Program using Extension .C • Before Program is given to compiler program is processed by Preprocessor . • begin main • Source Program is scanned from Left to Right and from Top to Bottom and “begin” is replaced by “main” • So Programmer feels that “He has written Code Without using Main , but internally begin is already converted into main”
• 5.
  1 2 3 4 5 6 #include<stdio.h> #define begin m##a##i##n voidbegin() { printf("Hello"); } Way 2 : Using #define Token Merging Operator Explain ? • The ‘##‘ operator is called the token pasting or token merging operator. • That is we can merge two or more characters with it.
• 6.
  1 2 3 4 5 6 #include<stdio.h> #define begin m##a##i##n voidbegin() { printf("Hello"); } Way 3 : Using Argumented Macro