The "if-else" structure is another form of if statement that is specially used for making two way decision. In its structure, one test condition and two blocks of statements are used to make decision. When the given condition is true, the first block is Executed whereas other block is ignored. Similarly, second block is executed if the given condition becomes false.

Declaration

In C++, the general syntax of 'if-else' is as follows:

if (test_condition)

      first_statement;

else

      second_statement;

Where:
In the case of compound statement, the if-else syntax will be as follows:

if (condition or set of conditions)

   {

      group_of_statement_1

   }

else

   {

      group_of_statement_2

   }

In the above syntax, " group_of_statement_1 and group_of_statement_2 " indicates set of statement that will be executed or ignored according to the test condition.

Flowchart

The flowchart of C++ if else structure is as follows:

Example Programs

Example 1: The following source code of the program inputs two values from the user and finds the large value from them.

#include

#include

main()

 {

      int num1, num2, large;

      clrscr();

      cout
      cin>>num1;

      cout
      cin>>num2;

      if

            (num1 > num2)

            large = num1;

      else

            large = num2;

  cout
getch();

} // end main function

In the above program, num1, num2 and large are tree variables of integer data type. When the user enter two values, then if condition (num1 > num 2) is evaluate, suppose, we entered 5 and 3 respectively, then the condition looks like "5 > 4" which is absolutely true, in this case, "num1" value assigned to the variable "large" and its result will be display as large value.

Example 2: The following program inputs a value and finds whether the entered value is even or odd by using if else.

#include

#include

main()

 {

      int num;

      clrscr ();

      cout
      cin>>num;

      if (num%2==0)

            cout
     else

            cout
      cout
      getch();

 }


 

Output of the Program:
(suppose we entered 20)

Enter value: 20
20 is even number
Done

Example 3: The following program inputs a year and finds whether it is leap year or not.

#include

#include

main()

 {

      int year;

      clrscr ();

      cout
      cin>>num;

      if (year%4==0) //leap year divisible by 4

            cout
     else

            cout
      getch();

 }

Output of the Program:
(suppose we entered 2020)

Enter a year: 2020
2020 is a leap yaer.