Control statements or decision making in C++

Control statements are used to control and execute the statements based on certain conditions or repeat a group of statements until certain specified conditions are met

There are different types of if statements in C++.

• if statement
• if-else statement
• nested if statement
• if-else-if ladder

if Statement:

if statement checks the condition. It is executed if condition is true.

Syntax:

    if(condition){    

   //statement

             } 

    Example:

#  include< iostream.h>

#  include<conio.h>  

    int main( )

{   
     int x,y;

    clrscr();

    cout<<"Enter two number"<<endl;

      cin>>x>>y;

      if (x > y )

      {

      cout << "x is greater than y";

        }

     return 0;

}

if-else Statement

If-else statement checks the condition. It executes if condition is true otherwise it comes to else block and else block will be executed.

Syntax:

     if(condition){    

     //statement

               }

         else{    

        //statement

                  }    
     Example:

   #include< iostream.h>
   #include<conio.h>
    int main( ){
    int x,y;

    clrscr();

     cout<<"Enter two number"<<endl;

      cin>>x>>y;

         if (x > y )

     {

  cout << "x is greater than y";

     }

      else{

   cout << "x is smaller than y";
          } 

    return 0;
             }

If-else-if ladder Statement

if-else-if ladder statement executes one condition from multiple conditions.It will check the conditions one by one ,if the condition is true then print the output otherwise it comes to  else block and else block will be executed.

Syntax:

   if(condition1){   
     / /statement

}   
     else if(condition2){    

     //statement

}  
     else if(condition3){    

      //statement

}   

       ...........................    

     else{    
     //statement

        }

   Example:
    #include< iostream.h>

    #include<conio.h>

    int main( )
     {
   int x;

   clrscr();

   cout<<"Enter a number to check whether number is +ve,-ve or zero"<<endl;

   cin>>x;

   if (x > 0 )

   {

    cout << "Number is Positive"<<endl;

    }

     else if (x < 0 )

   {

    cout << "Number is Negative"<<endl;

    }

    else{

    cout << "Number is zero"<<endl;

    }

    return 0;

} 

switch

switch statement executes one statement from multiple conditions. It will check the conditions one by one. If it finds true, it will print the output otherwise it comes to default and default statement will be executed. It is just like if-else-if ladder

Syntax:

switch(expression){      

case value1:      

 //statement

 break;    

case value2:      

 //statement

 break;    

......      

      

default:       

 //statement

}    

Example:
 # include <iostream.h>  
   #include<conio.h>

     int main () {  

       int number;  

       cout<<"Enter a number :";    

       cin>> number;  

           switch (number)    

          {    

        case 1:

         cout<<"It is one";

       break;    

  case 2: 

      cout<<"It is two"; 

        break;    

      case 3: 

      cout<<"It is three"; 

     break;    

             

    default:

    cout<<"Invalid"; 

          }    

    }