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Solution of Warning implicit declaration of function 'getpid' in C

Here, we are going to learn how to fix the issue of “Warning implicit declaration of function 'getpid'” while compiling C program? By IncludeHelp Last updated : March 31, 2023

What is implicit declaration of function 'getpid' Warning?

Warning implicit declaration of function 'getpid' - While getting Process Id, this is the common warning which occurs.

Example

Consider the following code snippet

#include <stdio.h>
 
int main()
{
    printf("Process Id is: %ld\n",getpid());
    return 0;
}

See the warning after compiling the program

    warning: implicit declaration of function 'getpid'

This is the same problem, for which you are looking?

Solution

getpid() - is used to get process id of the current process, and it is declared in <unistd.h> header file.

The warning occurs, if you do not include this header file, to fix the warning include <unistd.h> header file in the program.

SOLVED Example

Consider the code snippet

#include <stdio.h>
#include <unistd.h>
 
int main()
{
    printf("Process Id is: %ld\n",getpid());
    return 0;
}

Output

    Process Id is: 98

Related program...

C program to get Process Id and Parent Process Id in Linux.