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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <string.h>
  4. #include <unistd.h>
  5. #include <sys/types.h>
  6.  
  7. // we'll be setting up an array of four descriptors
  8. #define PARENT_READ     0
  9. #define CHILD_WRITE     1
  10. #define CHILD_READ      2
  11. #define PARENT_WRITE    3
  12.  
  13. int main()
  14. {
  15.     int fd[4];
  16.     char msg[256];
  17.     pid_t pid;
  18.  
  19.     pipe(fd);       // [0] = parent-read, [1] = child-write
  20.     pipe(fd+2);     // [0] = child-read, [1] = parent-write
  21.  
  22.     if((pid = fork()) == 0)
  23.     {
  24.         // child process.
  25.         close(fd[PARENT_READ]);
  26.         close(fd[PARENT_WRITE]);
  27.  
  28.         read(fd[CHILD_READ], msg, sizeof(msg));
  29.         printf("READ = %s", msg);
  30.         strcpy(msg, "YES");
  31.         write(fd[CHILD_WRITE], msg, strlen(msg)+1);
  32.  
  33.         close(fd[CHILD_READ]);
  34.         close(fd[CHILD_WRITE]);
  35.  
  36.         return EXIT_SUCCESS;
  37.     }
  38.  
  39.     // parent process
  40.     close(fd[CHILD_READ]);
  41.     close(fd[CHILD_WRITE]);
  42.  
  43.     strcpy(msg, "HI!! YOU THERE");
  44.     write(fd[PARENT_WRITE], msg, strlen(msg)+1);
  45.     read(fd[PARENT_READ], msg, sizeof(msg));
  46.     printf("\nACK RECEIVED %s\n", msg);
  47.  
  48.     close(fd[PARENT_READ]);
  49.     close(fd[PARENT_WRITE]);
  50.  
  51.     return EXIT_SUCCESS;
  52. }
Success #stdin #stdout 0s 2248KB
comments (?)
stdin
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Standard input is empty
stdout
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READ = HI!! YOU THERE
ACK RECEIVED YES
https://ideone.com/lohndd
language:
C (gcc 8.3)
created:
10 years ago
visibility:
secret

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