The if-else-if structure is also known as nested if else structure or multiple if else structure. It is used to execute one block of statements from multiple blocks of statements.
In C++ if else if structure, multiple conditions and multiple blocks of statements are given. When any of the given condition is true, the statements associated with that condition are executed. In this case, all other blocks are ignored.
The general syntax of "if-else-if" structure is as follows:

if (condition-1)
      { Block-1 }
else if (condition-2)
      { Block-2 }
else if (condition-3)
      { Block-3 }
----------------
----------------
else if (condition-m)
      { Block-m }
   else
      { Block-n}

Flowchart of if else if Structure

Following is the flowchart:

Execution of if else if statements

In C++, the if else if structure is executed by following these rules:

• The conditions are evaluated in the given sequence until a true condition is found.
• The statements associated with true condition are executed.
• The block of statements of following the last else is executed if all conditions are false.

Example Programs

Example 1: The following program finds out whether a number is positive, negative or zero by using C++ if-else-if statement.

#include
using namespace std;
main()
 {
   int num;
   cout   cin>>num;
   if (num >0 )
      cout   else if (num       cout   else
      cout   return 0;
 }

In the above source code, "if-else-if" statement is used. Suppose the user enters a positive number, the number is tested with if statement.  The answer is true because number is positive. The message is displayed on the screen and rest of the conditions will be ignored.

Example 2: The following source code of the program inputs any character through keyboard and determines whether it is a capital letter, small letter, a digit or a special character symbol using logical operators and "if-else-if" statement.

#include
using namespace std;
main()
 {
   char ch;
   cout   cin>>ch;
   if (ch>='A' && ch       cout   else if (ch>= 'a' && ch      cout   else if (ch>= '0' && ch       cout   else
      cout   getch();
 }

Example 3: The following source code inputs three numbers and finds out the smallest number using logical operators and "if-else-if" statement.

#include
using namespace std;
main()
 {
   int num1, num2, num3, mini;
   cout   cin>>num1;
   cout   cin>>num2;
   cout   cin>>num3;
   if (num1       mini = num1;
   else if (num2       mini = num2;
   else
      mini = num3
   cout   return 0;
 }

Example 4: The following source code of program performs simple arithmetic calculations using "if-else-if" statement.

#include
using namespace std;
main()
 {
   float n, m; char opt;
   cout   cin>>n>>opt>>m;
   if (opt == '-')
      cout   else if (opt == '*')
      cout   else if (opt == '/')
      cout   else
      cout   return 0;
 }

Output of the program:
Enter first value, operator and second value:
4+6