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Print error message from any function with function name, line number in C

Example of __LINE__ and __func__ preprocessor directive in C language: Here, we will learn how to print error message from any function with function name, line number in C language?
By IncludeHelp Last updated : March 10, 2024

Sometimes, it is necessary to print some message on logic failure or anytime with the function name and line number, so that program can be debugged and fixed the issue.

Prerequisite

__LINE__: To print current line number
__func__: To print the name of the current function

Program

#include <stdio.h>

float devide(int a, int b)
{
	float result;
	
	if(b!=0){
		result = (float)a/(float)b;
	}
	else{
		result=0;
		printf("Error at line %d in function \"%s\"\n",((__LINE__)-3),__func__);
		//ERROR at 3 lines above: ((__LINE__)-3)
	}

	return result;
}

int main()
{
	printf("%f\n",devide(10,3));
	printf("%f\n",devide(10,0));	
	return 0;
}

Output

3.333333
Error at line 9 in function "devide"
0.000000