streams-and-buffering.c

File: streams-and-buffering.c

/**
 * visualizza, carattere-per-carattere, una serie di righe per evidenziare la
 * differenza in termini di buffering tra lo standard output (line buffered) e
 * lo standard error (unbuffered)
 */
 
#include "lib-misc.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
 
#define PHRASE "Hello World!"
#define LINES 3
 
void print_phrases(FILE *channel) {
    char phrase[] = PHRASE;
    struct timespec pause = {0, 100 * 1000000};
 
    for (int i = 0; i < LINES; i++) {
        for (int j = 0; j < strlen(phrase); j++) {
            nanosleep(&pause, NULL);
            fputc(phrase[j], channel);
        }
        fputc('\n', channel);
    }
}
 
int main(int argc, char *argv[]) {
 
    printf("Messaggio sullo standard error (unbuffered): \n");
    print_phrases(stderr);
 
    printf("\nMessaggio sullo standard output (line buffered): \n");
    print_phrases(stdout);
 
    printf("\nDisabilito buffering su standard output...\n");
    setbuf(stdout, NULL);
    printf("\nMessaggio sullo standard output (unbuffered): \n");
    print_phrases(stdout);
 
    exit(EXIT_SUCCESS);
}