/* This example creates a pipe, forks a child then sends 42 down the pipe.
It uses non-ansi C function fdopen to allow stream operations on the pipe.
*/

#include <unistd.h>
#include <stdio.h>

void parent(int fd[]) {
    FILE* out;
    close(fd[0]);	/* won't be reading this end.*/
    printf("Sending 42\n");
    out=fdopen(fd[1],"w");
    fprintf(out,"%d",42);
    fclose(out);
}

void child(int fd[]) {
    FILE* pipein;
    int num;
    close(fd[1]);     /* won't be writing.*/
    sleep(1);
    pipein=fdopen(fd[0],"r");
    fscanf(pipein,"%d",&num);
    printf("Read value %d\n",num);
    fclose(pipein);
}

int main(int argc, char** argv)
{
    int fd[2];
    pid_t pid;
    if (pipe(fd)!=0) {
        perror("Problem with pipe");
    }
    pid=fork();
    if (pid==0) {
        parent(fd);
    }
    else if (pid>0) {
        child(fd);
    } else {
        // fork problem
    }
    return 0;
}