Question

有什么方法可以使子进程两次运行其代码？

例如，如果我们有此代码

pid_t child;
child=fork();
if (child<0) printf("error");
else if (child==0) printf("Hello world, I am the child");
else printf("This is the father");

else之后，我怎么称呼孩子以便再次打印“ Hello world ...”？

Answer 1

我只是在这里猜测，但是也许您希望子进程自己运行多个语句？然后，您可以通过将它们全部放在if (child == 0)块中来做到这一点：

if (child == 0)
{
    // Here you can have as many statements as you want
    // The process will continue to run until you explicitly call exit
    // or until you return from the main function

    // If you need to do multiple things, then my suggestion is that
    // you put this code in a function that you call
    // Then when the function returns you call exit to end the process

    exit(0);  // Exit the child process only, the parent can still continue
}

Answer 2

您有一个“子”变量，该变量存储fork（）函数的返回值（可能是进程ID，但是pid_t能够存储您希望存储的任何带符号的32位int）。然后，将此值与int（0）进行比较。如果要再次打印“ Hello world ...”，则只需使用printf（）或if（...）printf（）添加一行代码。希望我理解您的要求并能够提供帮助。

如何两次调用子进程

2 个答案: