# error directive in c

Syntax : #error

If compiler compiles this line then it shows a compiler fatal error i.e it only issue an error message and this error message includes . i.e it only issue an error message and this error message includes .

Example :

#include<stdio.h>

#ifndef __MATH_H

#error First include then compile

#else

int main(){

    float a,b=25;

    a=sqrt(b);

    printf("%f",a);

    return 0;

}

#endif

Output: compiler error --> Error directive :First include then compile

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