C program to find number of days in month

Example
Input

Enter month number: 1

Output

It contains 31 days.

Logic to find number of days in a month

Total days in a months is given by below table.

Month	Total days
January, March, May, July, August, October, December	31 days
February	28/29 days
April, June, September, November	30 days

Step by step descriptive logic to find number of days in given month.

1. Input month number from user. Store it in some variable say month.
2. For each month check separately and print corresponding number of days in that month using above table. For example, print 31 days if month == 1 since, January contains 31 days.
3. Repeat the above step for all 12 months.

/**
 * C program to print number of days in a month
 */

#include <stdio.h>

int main()
{
    int month;

    /* Input month number from user */
    printf("Enter month number (1-12): ");
    scanf("%d", &month);


    if(month == 1)
    {
        printf("31 days");
    }
    else if(month == 2)
    {
        printf("28 or 29 days");
    }
    else if(month == 3)
    {
        printf("31 days");
    }
    else if(month == 4)
    {
        printf("30 days");
    }
    else if(month == 5)
    {
        printf("31 days");
    }
    else if(month == 6)
    {
        printf("30 days");
    }
    else if(month == 7)
    {
        printf("31 days");
    }
    else if(month == 8)
    {
        printf("31 days");
    }
    else if(month == 9)
    {
        printf("30 days");
    }
    else if(month == 10)
    {
        printf("31 days");
    }
    else if(month == 11)
    {
        printf("30 days");
    }
    else if(month == 12)
    {
        printf("31 days");
    }
    else
    {
        printf("Invalid input! Please enter month number between (1-12).");
    }

    return 0;
}

/*
Output :

Enter month number (1-12): 12
31 days
*/

Program to print days in a month using logical OR operator

/**
 * C program to print number of days in a month using logical operator
 */

#include <stdio.h>

int main()
{
    int month;

    /* Input month number from user */
    printf("Enter month number (1-12): ");
    scanf("%d", &month);


    /* Group all 31 days conditions together using logical OR operator */
    if(month==1 || month==3 || month==5 || month==7 || month==8 || month==10 || month==12)
    {
        printf("31 days");
    }
    else if(month==4 || month==6 || month==9 || month==11)
    {
        /* Group all 30 days months together */
        printf("30 days");
    }
    else if(month==2)
    {
        printf("28 or 29 days");
    }
    else
    {
        printf("Invalid input! Please enter month number between (1-12).");
    }

    return 0;
}

/*
Output :

Enter month number (1-12): 12
31 days
*/

Program to print days in a month using array

/**
 * C program to print number of days in a month using array
 */
 
#include <stdio.h>
 
int main()
{
    /* Constant number of month declarations */
    const int MONTHS[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
    int month;
 
    /* Input month number from user */
    printf("Enter month number (1-12): ");
    scanf("%d", &month);
 
 
    if(month >= 1 && month <= 12)
    {
        /* Print number of days */
	printf("%d days", MONTHS[month - 1]);
    }
    else
    {
        printf("Invalid input! Please enter month number between (1-12).");
    }
 
    return 0;
}

/*
Output :

Enter month number (1-12): 12
31 days
*/