4 October

// Assignment 4 solution.

// Stylistic point (Dijkstra): function or program should have a
// single entry point (main) and a single exit point (return 0). By
// returning from the middle of the program, after an error message,
// we're having multiple exits.

#include <stdio.h>

int main()
{
    int month, day;

    printf("Enter month (1-12): ");
    scanf("%d", &month);

    if(month < 1 || month > 12)
    {
        printf("Invalid month.\n");
        return 0;
    }

    printf("Enter day of month: ");
    scanf("%d", &day);

    int max_days;
    switch(month)
    {
    case 2:
        max_days = 28;
        break;
    case 4: case 6: case 9: case 11:
        max_days = 30;
        break;
    default:
        max_days = 31;
    }

    if(day < 1 || day > max_days)
    {
        printf("Invalid day.\n");
        return 0;
    }

    switch(month)
    {
    case 1: printf("January"); break;
    case 2: printf("February"); break;
    case 3: printf("March"); break;
    case 4: printf("April"); break;
    case 5: printf("May"); break;
    case 6: printf("June"); break;
    case 7: printf("July"); break;
    case 8: printf("August"); break;
    case 9: printf("September"); break;
    case 10: printf("October"); break;
    case 11: printf("November"); break;
    case 12: printf("December"); break;
    }

    printf(" %d", day);

    switch(day)
    {
    case 1: case 21: case 31:
        printf("st");
        break;
    case 2: case 22:
        printf("nd");
        break;
    case 3: case 23:
        printf("rd");
        break;
    default:
        printf("th");
    }
    printf("\n");

    return 0;
}