爲什麼我會收到大量的整數？

Question

我正在爲類應該從命令行中獲取數字的項目工作，然後將它們傳遞給子進程添加，然後父級應該收穫數字的總和。它似乎工作得很好，除非我收穫孩子的過程，它給了我大量的數字，而不是原來加在一起的數字的總和。如果我剛剛輸入0，則得到0，如果我輸入1，則得到256，依此類推。我錯過了什麼，我只是沒有正確收穫？謝謝。

enter code // Numbers from command line arguments are sent to child process 
// from parent process one at a time through pipe. 
// 
// Child process adds up numbers sent through pipe. 
// 
// Child process returns sum of numbers to parent process. 
// 
// Parent process prints sum of numbers. 


static int com[2]; 

int main(int argc, char **argv) 
{ 
    pid_t pid; 

    // set up pipe 

    if (pipe(com)) 
    { 
     printf("pipe error\n"); 
     return -1; 
    } 

    //call fork() 

    pid = fork(); 

    if (pid == 0) 
    { 
     // -- running in child process -- 

     int    sum = 0; 
     int    input = 0; 

     //close output end of pipe 

     close(com[1]); 

     // Receive characters from parent process via pipe 
     // one at a time, and count them. 

     for (int idx = 1; idx < argc; idx++) //stared idx at 1 instead of 0 
     { 
       read(com[0], &input, 4); //changed from 4 
       sum = sum + input; 
     } 
       printf("child sum: %i \n", sum); // error checking 

     // Return sum of numbers. 

     return sum; 
    } 
    else { 
      // -- running in parent process -- 

      int sum; 

      //close output end of pipe 

      close(com[0]); 

      // Send numbers (datatype: int, 4 bytes) from command line arguments 
      // starting with argv[1] one at a time through pipe to child process. 

      for (int idx = 1; idx < argc; idx++) 
      { 
        int output = 0; 

        output = atoi(argv[idx]); 
        write(com[1], &output, 4); 
        printf("output: %i \n", output);// error checking 
      } 

      close(com[1]); 

      // Wait for child process to return. Reap child process. 
      // Receive sum of numbers via the value returned when 
      // the child process is reaped. 

      waitpid(pid, &sum, 0); 

      printf("sum = %d\n", sum); 

      return 0; 
     } 
} 

這裏

Answer 1

從man page

如果狀態不爲空，等待（）和waitpid函數（）在INT存儲狀態信息，它指向。此整數可以用下面的宏其中

兩個是

WIFEXITED(status) 
    returns true if the child terminated normally, that is, by 
    calling exit(3) or _exit(2), or by returning from main(). 

WEXITSTATUS(status) 
    returns the exit status of the child. This consists of the 
    least significant 8 bits of the status argument that the child 
    specified in a call to exit(3) or _exit(2) or as the argument 
    for a return statement in main(). This macro should only be 
    employed if WIFEXITED returned true.