#include<stdio.h>
#include<stdlib.h>
#include<pthread.h>
int sum;
void *runner(void *param);
int main(int argc, char **argv)
{
pthread_t tid;
pthread_attr_t attr;
if(argc != 2)
{
fprintf(stderr,"usage:a.out<integer value>\n");
return -1;
}
if(atoi(argv[1]) < 0)
{
fprintf(stderr,"%d must be >= 0\n",atoi(argv[1]));
return -1;
}
pthread_attr_init(&attr);
pthread_create(&tid,&attr,runner,argv[1]);
pthread_join(tid,NULL);
printf("sum = %d\n",sum);
return 0;
}
void *runner(void *param)
{
int i,upper=atoi(param);
sum = 0;
for(i=1;i<=upper;i++)
{
sum+=i;
}
pthread_exit(0);
}
$ gcc 4.4.1_4-9.c -o 4.4.1_4-9.o
/tmp/ccWftpGc.o: In function `main':
4.4.1_4-9.c:(.text+0xc3): undefined reference to `pthread_create'
4.4.1_4-9.c:(.text+0xd4): undefined reference to `pthread_join'
collect2: error: ld returned 1 exit status
pthread 库不是 Linux 系统默认的库，连接时需要使用静态库 libpthread.a，所以在使用pthread_create()创建线程时，需要链接该库。
$ gcc 4.4.1_4-9.c -o 4.4.1_4-9.o -lpthread
