linxu中系统错误码errno

#include <iostream>
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <errno.h>
#include <string.h>

int main(int argc, char **argv)
{
    int sockfd = 0;
    
    if ((sockfd = socket(0, SOCK_STREAM, 0)) < 0)
    {
        if (errno >= 0 && errno <= sys_nerr)

        printf("socket created, failed[%d], reason:%s\n", errno, sys_errlist[errno]);
　　　　 printf("%s\n",strerror(errno));  //头文件string.h内
    }
    else
    {
        printf("socket successful\n");
    }
    
    return 0;
}

socket created, failed[97], reason:Address family not supported by protocol

Address family not supported by protocol