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perror() function of stdio.h in C

In this article, we are going to learn about the perror() function of stdio.h header file in C programming language, and use it prints a descriptive error message to stderr.
Submitted by Abhishek Sharma, on April 12, 2018 [Last updated : March 14, 2023]

perror() - Description and Usages

The perror() function is very useful as it prints the error message on the screen. All we have to do is if you have a situation where we caught an error; call this function with a parameter of string.

The String which will be printed first, a colon, a space then the error message.

Prototype

void perror(const char *str)

Parameter(s)

• str - A string containing a custom message that will be printed before the error message itself.

Return Type

Function's return type is void, it won't return anything.

Example

    perror("here is the error");
    will print →
    here is the error : ERROR MESSAGE.

stdio.h - perror() function Example in C

#include <stdio.h>

int main()
{
    // defining the file pointer
    FILE* f;

    // rename file name
    rename("abc.txt", "abcd.txt");

    // open file
    f = fopen("file.txt", "r");

    // condition if error then print error
    if (f == NULL) {
        perror("Error in Code is: ");
        return (-1);
    }

    // close the file
    fclose(f);

    return (0);
}

Output

C stdio.h Library Functions Programs »

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