Predifined Macro Program

Predefined Macros Program

#include<stdio.h> 

#ifdef __STDC__ 

#define CONFORM “conforms” 

#else 

#define CONFORM “does not conform” 

#endif 

int main() 

{ 

printf(“Line %d of file %s has been executed\n”,__LINE__,__FILE__); printf(“This file was compiled at %s on %s\n”,__TIME__,__DATE__); printf(“This program %s to ANSI standards\n”,CONFORM); } 

Output: 

Line 9 of file p1.c has been executed 

This file was compiled at 13:36:39 on Mar 2 2021  

This program conforms to ANSI standards

Other Directives 

#error  

This directive causes the preprocessor to generate an error message and causes compilation to fail. 

Syntax: 

#error error_string 

Example: 

#if SIZE %2==0 

#error SIZE should not be an even number 

#endif 

If error occurred program compilation will not complete and therefore no executable program will be created.

Other Directives continued … 

 #pragma 

 

 This directive is used to specify options to the complier. These options are specific for the platform and the compiler. It tells compiler how it should process its inputs. 

Following program will be supported by Turbo C but not run on GCC. 

 #include<stdio.h> 

 void func1(); 

 void func2(); 

 #pragma startup func1 

 #pragma exit func2 

 void func1() 

 {

  printf(“\nInside func1()”); 

  } 

  

 void func2()

  { 

 printf(“\nInside func2()”); 

 } 

  

 int main() 

 { 

 printf(“\nInside main()”); 

 return 0;

 } 

 

 Output: 

 Inside func1() 

 Inside main() 

 Inside func2()

Also Read

1. Macros vs Functions
2. Preprocessor Syntax
3. Task Performed by Preprocessor
4. C program to find largest of two numbers using Structure
5. Define a macro EQUALSTR which accepts two strings and compare equality of both string