Time to seconds

time_to_seconds.c

#include <stdlib.h>
#include <stdio.h>

// 1h 26m 15s -> 5175
unsigned int time_to_seconds(const char *str) {
	const char *current = str;
	unsigned int seconds = 0, number = 0;
	while (*current) {
		switch (*current) {
			case 'h':
				seconds += number * 60 * 60;
				number = 0;
				break;
			case 'm':
				seconds += number * 60;
				number = 0;
				break;
			case 's':
				seconds += number;
				number = 0;
				break;
			case ' ':
				break;
			default:
				if (*current >= 48 && *current <= 57) { // 0-9
					number = number * 10 + (*current - 48);
				} else {
					int index = (int)(current - str);
					printf("Invalid character '%c' at %d\n", *current, index);
					exit(EXIT_FAILURE);
				}
				break;
		}	
		++current;
	}
	return seconds;
}

main(int argc, char *args[]) {
	if (argc > 1) {
		unsigned int seconds = time_to_seconds(args[1]); 
		printf("%s is %d seconds\n", args[1], seconds);
		exit(EXIT_SUCCESS);
	} else {
		printf("No input\n");
		exit(EXIT_FAILURE);
	}
}