Output not displayed with usleep until a line break is given

Question

I'm trying to program a simple "typewriter" effect in C, where text appears one letter at a time with a delay. Here's the function I have:

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

void typestring(const char *str, useconds_t delay)
{
    while (*str) {
        putchar(*(str++));
        usleep(delay);
    }
}

The problem is the text doesn't actually appear until a \n is displayed. What am I doing wrong?

Answer 1

The output to stdout is buffered. Using \n you are forcing a flush. If you want to change this, you will need to change the settings of the terminal (for Linux look here) or use

void typestring(const char *str, useconds_t delay)
{
    while (*str) {
        putchar(*(str++));
        fflush(stdout);
        usleep(delay);
    }
}