optimized.c

static void
_revwstr_(char *str, int first)
{
	int start;
	int i = 0;
	if (str[i]) {
		while (str[i] && (str[i] == ' ' || str[i] == '\t'))
			i++;
		if (!str[i])
			return ;
		start = i;
		while (str[i] && (str[i] != ' ' && str[i] != '\t'))
			i++;
		_revstr(&s[i], 0);
		write(1, &str[start], i - start);
		if (!first)
			write(1, " ", 1);
	}
}

revwstr.c

static void
_revwstr_(char *str, int first)
{
	int start;
	int i = 0;
	if (str[i]) {

        	/* Incrementation vers le premier mot */
		while (str[i] && (str[i] == ' ' || str[i] == '\t')) {
			i++;
		}
		if (!str[i]) {
			return ;
		}

        	/* Keep start in reference */
		start = i;

       		/* Incrementation sur le premier mot */
		while (str[i] && (str[i] != ' ' && str[i] != '\t')) {
			i++;
		}

        	/* Recurse operation to start at last word */
		_revstr(&s[i], 0);

		/* Print last word first word */
		write(1, &str[start], i - start);

		/* Helper to pass on first word */
		if (!first) {
			write(1, " ", 1);
		}
	}
}