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The C programming language made simple

Two way communication between processes (using pipes) in C

#include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/types.h> #include <sys/wait.h> #include <time.h> int main(int argc, char* argv[]) { int p1[2]; int p2[2]; if (pipe(p1) == -1) { return 1; } if (pipe(p2) == -1) { return 2; } int pid = fork(); if (pid == -1) { return 3; } if (pid == 0) { // Child process close(p1[0]); close(p2[1]); int x; if (read(p1[0], &x, sizeof(int)) == -1) { return 3; } printf("Received %d\n", x); x *= 4; if (write(p2[1], &x, sizeof(int)) == -1) { return 4; } printf("Wrote %d\n", x); close(p1[1]); close(p2[0]); } else { // Parent process close(p1[1]); close(p2[0]); srand(time(NULL)); int y = rand() % 10; if (write(p1[1], &y, sizeof(y)) == -1) { return 5; } printf("Wrote %d\n", y); if (read(p2[0], &y, sizeof(y)) == -1) { return 6; } printf("Result is %d\n", y); close(p1[0]); close(p2[1]); wait(NULL); } return 0; }