If and If-Else Program

If statement :-

The if statement evaluates the test expression inside parentheses.

If test expression is evaluated to true ( nonzero ), statements inside the body of if is executed.

If test expression is evaluated to false ( 0 ), statement inside the body of if is skipped.


Flow Chart of if statement :-

Basic if syntax :-

if ( statement is TRUE ) {
    /* between the braces is the body of the if statement */
    Execute all statements inside the body
}

Example :-

Ques - Program to Print number is even.

#include <iostream> //Header file
using namespace std;

int main() //Main function
{
    int number;

    cout<<"Enter a number :"; // Print on the screen
    cin>>number; // Take input from the console / user.

    // Test expression is true if number is perfectly divide by 2
    if ( number % 2 == 0) // % means find remainder , == means perfectly equal
    {
        cout<<"Even number";
    }

    return 0;
}

Output :

Enter an number:2
Even number

If else statement :-

If test expression is true, code inside the body of if statement is executed; and code inside the body of else statement is skipped.

If test expression is false, code inside the body of else statement is executed; and code inside the body of if statement is skipped.

Flow Chart of if..else statement :-

Basic if syntax :-

if ( TRUE ) {
    /* Execute these statements if TRUE */
}
else {
    /* Execute these statements if FALSE */
}

Example :-

Ques - Program to check whether an integer entered by the user is odd or even.

#include <iostream>
using namespace std;
int main()
{
    int number;
    cout<<"Enter an integer: ";
    cin>>number;

    // True if remainder is 0
    if( number%2 == 0 )
        cout<<number<<" is an even integer.";
    else
        cout<<number<<" is an odd integer.";
    return 0;
}

Output 1:

Enter an integer: 7
7 is an odd integer.

Output 2:

Enter an integer: 8
8 is an even integer.