#include <stdio.h>
#include <stdarg.h>

/* The C Programming Language: 2nd Edition
 *
 * Exercise 7-3: Revise `minprintf` to handle more of the other facilities
 * of `printf`.
 *
 * Notes: It doesn't specify *which* facilities, or how many, so we'll choose
 * three:
 *
 *     o - octal
 *     x - hexadecimal
 *     c - unsigned char
 *
 * Since we're passing to printf(), this was easy. Doing it ourselves would
 * take some more work. But we'll skirt by with the minimum.
 */

void minprintf(char *fmt, ...) {
	va_list ap;
	char *p, *sval;
	int ival;
	double dval;
	va_start(ap, fmt);
	for (p = fmt; *p; p++) {
		if (*p != '%') {
			putchar(*p);
			continue;
		}
		switch (*++p) {
			case 'd':
				ival = va_arg(ap, int);
				printf("%d", ival);
				break;
			case 'f':
				dval = va_arg(ap, double);
				printf("%f", dval);
				break;
			case 's':
				for (sval = va_arg(ap, char *); *sval; sval++) {
					putchar(*sval);
				}
				break;
			case 'c':
				ival = va_arg(ap, int);
				printf("%c", ival);
				break;
			case 'x':
				ival = va_arg(ap, int);
				printf("0x");
				printf("%x", ival);
				break;
			case 'o':
				ival = va_arg(ap, int);
				printf("0o");
				printf("%o", ival);
				break;
			default:
				putchar(*p);
				break;
		}
	}
	va_end(ap);
}

int main(int argc, char *argv[]) {
	/* Should output 0o144 */
	minprintf("100 = %o\n", 100);
	/* Should output 0x64 */
	minprintf("100 = %x\n", 100);
	/* Should output a semicolon */
	minprintf("char(0x59) = %c\n", 59);
	return 0;
}