CODEWITHSUNDEEP
cshared-libraries
Michael
Michael

Reputation: 69

Why coudn't I use function grantpt in Linux?

I want to use function grantpt in my program. I include its header file <stdlib.h>, but the compiler still give me the warning: implicit declaration of grantpt, which means it cound't find the declaration in stdlib.h. I grep the header file and find the declaration: 

stdlib.h:920:extern int grantpt (int __fd) __THROW;

And my glibc version is 2.17, the official manual says this function is included since version 2.1.

Here is my test program: 

#include <stdio.h>
#include <stdlib.h>

typedef unsigned long u_l;  

int main(){
    int errno = grantpt(1);
    printf("errno = %d\n", errno);
    return 0;
}

Thanks a lot!

Upvotes: 0

Views: 1557

Answers (1)

Jeegar Patel
Jeegar Patel

Reputation: 27230

#define _XOPEN_SOURCE
#include <stdlib.h>
#include <stdio.h>
//#include<sys/poll.h>

typedef unsigned long u_l;

int main()
{
    int errno = grantpt(1);

    printf("errno = %d\n", errno);

    return 0;
}

This code compiles without that warning

See Man page clearly says that you need to define _XOPEN_SOURCE before including stdlib.h for accessing grantpt()

Upvotes: 2

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