Question

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Closed 11 years ago.

#include<pthread.h>
#include<stdio.h>
int value=0;
void *runner(void *param);
int main(int argc,char *argv[])
{
int pid;
pthread_t tid;
pthread_attr_t attr;
pid=fork();
if(pid==0){
pthread_attr_init(&attr);
pthread_create(&tid,&attr,runner,NULL);
pthread_join(tid,NULL);
printf("CHILD VALUE=%d",value);
}
else if(pid>0){
wait(NULL);
printf("PARENT VALUE=%d",value);
}
}


void *runner(void *param){
value=5;
pthread_exit(0);
}

what is the value of child and parent?? will the child and the thread created by it share the data? so output will be 5 and 0?

Answer 1

儿童及其所创造的read子能否分享数据?

页: 1 如果父母记忆犹新,可以认为儿童进程是a 。因此,父母对子女做出的任何改变都不见。

因此,产出为5和0。

是:儿童印刷5种,父母印刷0种(不一定按此顺序排列)。

Answer 2

情况是:

the child process is created by duplicating the memory space of the parent. It will see the same data as the parent, but it s only a copy, so they cannot interfere with eachother. Any subsequent changes done by the child process (or any of its threads!) will only be visible to itself.
the thread spawned by the child shares the memory space with the main thread of the child process and, again, sees a copy of the values in the parent process.

因此,由于在儿童体内所分配的胎面值只有儿童体内可见,而不是在母体体体内,结果为5和0。

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