C++ if-else Statements

The if-else statement is a conditional statement with an optional else. The if statement executes a block of statements is the condition is true, but does not do anything when condition is false. The if-else block contains code for both true and false conditions.

Advertisements

Each of the block in if-else construct will be enclosed using braces( { } ). The general form of if-else is given below.

if(expression)
{
    statement1;
    statement2;
}
else
{
    statement3;
    statement4;
}

Clearly, the a program executes if block when expression = true and executes else block when expression = false.

Example Program: if-else

// example program to demostrate if-else 
#include <cstdlib>
#include <iostream>
using namespace std;
int main()
{
    //Variable Declaration
    
    int x,y,total;
    
    //Variable Initialization
    
    x = 100;
    y = 200;
    total = 0;
    
    //the if-else block
    
    if(x < 100)
    {
         total = x + y;
    }
    else
    {
         total = y - x;
    }
    
    //Printing the output
    
    cout << "Total =" << total << endl;
    
    system("PAUSE");
    return EXIT_SUCCESS;
}

Output:

Total =100

In the above example, the condition x < 100 is false. As a result, the else block is executed giving an output 100.

Advertisements

Types of if-else Constructs

There are several ways to construct if-else structure. Here is a list of possible constructs.

#1

if(expression)
{
    statement1;
    statement2;
}
else
{
    statement3;
}

#2

if(expression)
{ 
   if(expression)
   {
      statement1;
      statement2;
   }   else   {
      statement3;
   }
}
else
{
    statement4;
}

#3

if(expression)
{
           if(expression)
          {   
              statement1;
          }
           else
         {
             statement2;
         }
}
else
{
           if(expression)
          {
                statement3;
          }
           else
         {
               statement4;
         }
}

#4

if(expression)
{
}
else if(expression)
{
}
else if(expression)
{
}
else if(expression)
{
}

You can create different kinds of if-else constructs which one of the above construct as building blocks.



Advertisements

Ads Blocker Image Powered by Code Help Pro

Ads Blocker Detected!!!

We have detected that you are using extensions to block ads. Please support us by disabling these ads blocker.