Example: Time Converter (24-hour & Standard) in C

// Time Converter (24-hour & Standard)
#include <stdio.h>

int main() {
    int hours, minutes, seconds; // Variables to store input time
    char *am_pm;                 // Pointer to store "AM" or "PM" string
    int display_hour;            // Variable to store hour in 12-hour format

    // Step 1: Prompt user for time input
    printf("Enter time (hours minutes seconds, e.g., 14 35 20): ");
    scanf("%d %d %d", &hours, &minutes, &seconds);

    // Step 2: Validate input
    if (hours < 0 || hours > 23 || minutes < 0 || minutes > 59 || seconds < 0 || seconds > 59) {
        printf("Invalid time input. Hours must be 0-23, minutes 0-59, seconds 0-59.\n");
        return 1; // Indicate error
    }

    // Step 3: Print time in 24-hour format
    printf("24-Hour Format: %02d:%02d:%02d\n", hours, minutes, seconds);

    // Step 4: Determine AM/PM and convert hour for 12-hour format
    if (hours < 12) {
        am_pm = "AM";
        display_hour = hours;
        if (display_hour == 0) { // Special case for midnight (00:xx:xx -> 12:xx:xx AM)
            display_hour = 12;
        }
    } else {
        am_pm = "PM";
        display_hour = hours - 12;
        if (display_hour == 0) { // Special case for noon (12:xx:xx -> 12:xx:xx PM)
            display_hour = 12;
        }
    }

    // Step 5: Print time in standard (12-hour) format
    printf("Standard Format: %02d:%02d:%02d %s\n", display_hour, minutes, seconds, am_pm);

    return 0; // Indicate success
}