Number of days in a month

C program to read any Month Number in integer and display the number of days for that month.

Program

#include<stdio.h>
#include<conio.h>
void main()
{
	int num;

    printf("Enter the month number between 1 to 12\t:");
    scanf("%d",&num);

    if(num == 1 || num == 3 || num == 5 || num == 7 || num == 8 || num == 10 || num == 12)
    {
        printf("Month has 31 days");
    }
    else if(num == 2)
    {
        printf("February month has 28 days and in leap year 29 days");
    }
    else if(num == 4 || num == 6 || num == 9 || num == 11)
    {
        printf("Month has 30 days");
    }
    else
    {
        printf("Invalid input");
    }

    getch();
}

Output

********** Run1 ********** 

Enter the month number between 1 to 12  :5
Month has 31 days


********** Run2 ********** 

Enter the month number between 1 to 12  :9
Month has 30 days

Explanation

Months in number are as follows:
1 - January
2 - February
3 - March
4 - April
5 - May
6 - June
7 - July
8 - August
9 - September
10 - October
11 - November
12 - December

January, March, May, July, August, October, December has 31 days. So, instead of making Different conditions for each month, OR (||) logical operator is used.
if(num == 1 || num == 3 || num == 5 || num == 7 || num == 8 || num == 10 || num == 12)
February has 28 or 29 days depending on the year (leap year or not)
else if(num == 2)
April, June, September, November has 30 days. So, the condition is as follows:
else if(num == 4 || num == 6 || num == 9 || num == 11)