C中的waitpid調用

Question

我已經創建了一個簡單的程序來驗證在waitpid（）調用中使用statloc參數是否通過演示子進程和父進程。我已經讀過某處通過exit（）在任何進程中通過statloc返回到父節點的返回值。因此，我試圖在父上下文中打印statloc變量，但它與我通過exit（）返回的內容不同。如果我誤解了，請糾正我。下面的代碼和結果：（我期待234 statloc值）

#include<stdio.h> 
#include<stdlib.h> 
#include<sys/types.h> 
#include<sys/wait.h> 

int main() 

{ 
pid_t pid; 
char ch; 
int statloc; 



if((pid=fork())!=0) 
{ 

/* parents code */ 
printf("\n pid of child process is %d ", pid); 

printf("\nI am in parent "); 

waitpid(-1,&statloc,0); 

printf("\n I have yet not exited from parent "); 
printf("\n value of statloc is %d ",statloc) ; // expecting 234 as statloc's value 

exit(0); 
} 

if(pid==0) 
{ 

printf("\n hello, in child's code \n"); 

printf("\n Exiting child's code \n "); 
exit(234); 

}  

} 

輸出

：

avotclbh:/home/akhils/prep#./a.out 

hello, in child's code 

Exiting child's code 
pid of child process is 12464 
I am in parent 
I have yet not exited from parent 
value of statloc is 59904 

Answer 1

使用WEXITSTATUS(statloc)得到子進程退出代碼。