do


  Statement


while (Expression);




- Statement is executed first without testing any condition

- If the value of the -logical- expression is true, Statement is executed again

- If the value of the expression is false, execution continues at the statement 
immediately following the loop





 Compound do-while statement

do


{


  Statement1;


  Statement2;


 ... 


  StatementN;


} while (Expression);

 while statement vs do-while statement

- In the case of the while statement, the condition is tested in the beginning

- In the case of the do-while statement, the condition is tested at the end

- As a result, the body of the do-while statement will be executed at least one
time !!! 






 The for statement

- A looping control structure

- Simplifies the design of count-controlled loops




- Examples

for(count = 1; count <= 10; count++)


  cout << count << endl;

for(count = 10; count <= 1; count--)


  cout << count << endl;

 Any for statement corresponds to a while statement



 Compound for statement

for(InitStatement; LogicalExpression1; Expression2)
br
{


  Statement1;


  Statement2;


 ... 


  StatementN;


}

 Nested for statement



 The break statement

- It is used with the switch statement and with loop statements (i.e., while, for, do-while)

- It causes an immediate exit from the switch or from the loop



sum=0;


for (i=0; i<=10; i++)


{


 cout << "Enter a number";


 cin >> num;


 if(num == -9999)


   break;


 sum = sum + num


}

- What if we have a nested loop statement ? 

- break causes an immediate exit from the innermost loop only !! 

sum=0;


for (i=0; i<=10; i++)


{


 cout << "Enter a number";


 cin >> num;


 for(j=0; j<=10; j++)


 {


   if(sum  > 1000)


     break;    


   sum =  sum * j * num;


  }


}

 The continue statement

- It is used with loop statements (i.e., while, for, do-while)

- It causes an immediate branch to the bottom of the loop

sum=0;


for (i=0; i<=10; i++)


{


 cout << "Enter a number";


 cin >> num;


 if(num == -9999)


   continue;


 sum = sum + num


}

Recommended exercises

- Quick Check excersices: 1, 2, 3, 5

- Exam preparation excersices: 5, 6, 7, 9, 10, 11, 12