Preprocessor in C

By: adarshsojitra on 15:54

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Preprocessor is very good feature of c programming language.It will increase the readability of any program.The C preprocessor provides several things that are unavailable in other high-level programming languages.Preprocesors starts with the symbol '#'. We have used it many times in c programming at the time when we include any file at the starting of the program.A set of commonly used preprocesors are shown below:

1.Macro submission Directives
2.File inclusion directives.

The preprocessor directives can be placed anywhere in c program before main() function or and UDF function.

Let us understand bit about macro by the following programs:
1.First program

#include<stdio.h>
#include<conio.h>
#define Pi 3.14
main()
{
         float r=5,ans;
         clrscr();
         ans=Pi*r*r;
         printf("Area of circle having radius %f is %f",r,ans);
         getch();
}

output:
Area of circle having radius 5.000000 is 78.500000

2.Second program

#include<stdio.h>
#include<conio.h>
#define condition (20<=a<=30)
main()
{
    int a=25;
    clrscr();
    if(condition)
    {
        printf("True");
    }
    else
    {
        printf("Flase");
    }
    getch();
}