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The C programming language made simple

Communicating 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 <errno.h> int main(int argc, char* argv[]) { int fd[2]; if (pipe(fd) == -1) { printf("An error ocurred with opening the pipe\n"); return 1; } int id = fork(); if (id == -1) { printf("An error ocurred with fork\n"); return 2; } if (id == 0) { // Child process close(fd[0]); int x; printf("Input a number: "); scanf("%d", &x); if (write(fd[1], &x, sizeof(int)) == -1) { printf("An error ocurred with writing to the pipe\n"); return 3; } close(fd[1]); } else { // Parent process close(fd[1]); int y; if (read(fd[0], &y, sizeof(int)) == -1) { printf("An error ocurred with reading from the pipe\n"); return 4; } printf("Got from child process %d\n", y); y = y * 3; printf("Result is %d\n", y); close(fd[0]); } return 0; }