Question

我必须知道,如何把两个简单的C方案的投入和产出同时联系起来,把第三个 Java/C方案联系起来。

我曾尝试过管道、袖珍和客户的连接,但是,如果只使用扫描仪和印刷件,便无法使用简单的C方案。

Sample programs: Program1.c

#include<stdio.h>
int main(int argc,char *argv[])
{
  int a;
  while(1)
  {
    scanf("%d",&a);
    printf("%d",a);
  }
  return 0;
}

方案2.c

#include<stdio.h>
int main(int argc,char *argv[])
{
  int a;
  while(1)
  {
    scanf("%d",&a);
    printf("%d",a);
  }
  return 0;
}

My aim is to connect stdin and stdout of program1.c with stdin and stdout of program2.c with the help of a third Java or C program

Answer 1

基本上,你们想要做这样的事情:

“Program3” creates a pipe
Program 3 calls fork, and in the child, changes out the pipe s FD for stdout, then exec s Program2;
Program 3 then changes out the pipe for stdin, and exec s Program1

Answer 2

You should use fork and exec
Write a third C program, which would open a two pipes (using pipe). This gives you 4 file descriptors (2 input, 2 output).
Then it forks - the child will later run program1 and the parent program2 (or vice versa - doesn t matter).
Each of the children will close 2 file descriptors, and remain with one input and one output (but not of the same pipe). They should also close standard input and output.
Then use the dup2 function to make the pipe fds become 0 and 1.
Now you have two processes, with one s stdin connected by pipe to the other s stdout, and vice versa.
The last stage is to use exec to make the run program1 and program2.

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