Study Material

Selection Structure

The ‘if’ Statement:

              The ‘if’ statement is a simple selection statement. It is decision making statement. It is used to execute or skip a statement or a set of statement after testing a condition.

  

  Syntax

     If(condition)

     { 
        Statement-1;

        Statement-2;

        ……….…

        Statement-m; 
       }

        Statement-n;

  Example

     #include<iostream>

     using namespace std;

     int main( )

   {  
       int a,b;

       cout<<"Enter First Number =";

       cin>>a;

       cout<<"Enter second Number =";

       cin>>b;

       if(a>b)

       cout<<”A is greater” <<a;

       if(a<b)

       cout<<”B is greater”<<b;

       return 0;
      }

The ‘if else’ Statement:

              The ‘if else’ statement is another form of ‘if’ statement. It is used to making two way decision. In ‘if else’ statement  one condition and two block of statement givens. It is execute first block if condition is true otherwise next  block execute.

  Syntax

     if(condition)

    {
      Block-1

       }

     else

    {

     Block-2

     }

  Example

   #include<iostream>

   using namespace std;

   int main( )

 {

   int a,b;

   cout<<"Enter First Number =";

   cin>>a;

   cout<<"Enter second Number =";

   cin>>b;

   if(a>b)

   cout<<”A is greater” <<a;

  else

   cout<<”B is greater”<<b;

   return 0;

   }

The nested ‘if’ Statement:

An ‘if’ statement within another ‘if’ statement is called nested ‘if’ statement. The ‘if’ statement contain another ‘if’ statement is called outer ‘if’ statement and the statement used inside called inner ‘if’ statement.

 Syntax

   if(condition-1)

  {

    if(condition-2)

    {

      Block-1;

       }

  else

  {

    Block-2;

    }

  else

 {

   Block-3;

   }

 Example

   #include<iostream>

   using namespace std;

   int main( )

 {

   int a,b,c;

   cout<<"Enter First Number =";

   cin>>a;

   cout<<"Enter second Number =";

   cin>>b;

   cout<<"Enter third Number =";

   cin>>c;

  if(a>b)

 {

  if(a>b)

   cout<<”A is greater” <<a;

 else

   cout<<”B is greater”<<b;

   }

else

   cout<<”C is greater”<<c

  return 0;

  }

The Switch Statement:

The ‘switch’ statement is another selection structure. It can be used alternative of ‘if else if’ statement. It is used when multiple choice are given and  one choice is selected.

 Syntax

   switch(expression)

 {

  case 1:

          Statement-1;

          break;

  case 2:

          Statement-2;

          break;

  …   ………….

  …   ………….

 default:

          statement-n

  }

Example

 #include<iostream>

 using namespace std;

 int main( )

{

 char ch;

 cout<<”Enter Character”;

 cin>>ch;

 switch(ch)
{

     case ‘a’:
     case ‘A’:

     case ‘e’:

     case ‘E’:

     case ‘i’:

     case ‘I’:

     case ‘o’:

     case ‘O’:

     case ‘u’:

     case ‘U’:

           cout<<”It is vowel”;
     break;

    default:

           cout<<”It is consonant”;
}

  return 0;

  }