C++ Part 21

While and do-while Statements
A while STATEMENT WITH A SINGLE-STATEMENT BODY

while (Boolean_Expression) Statement A while STATEMENT WITH A MULTISTATEMENT BODY while (Boolean_Expression) { Statement_1 Statement_2 . . . Statement_Last } A do-while STATEMENT WITH A SINGLE-STATEMENT BODY do Statement while (Boolean_Expression); A do-while STATEMENT WITH A MULTISTATEMENT BODY do { Statement_1 Statement_2 . . . Statement_Last } while (Boolean_Expression); Do not forget the final semicolon.

C++ Part 15

Iteration

while: execute a statement as long as some condition is true

do while: similar to while but check condition after executing the statement.

for: execute a statement on every element of some data, or some fixed number of times.

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while {loop body}

int count = 0 ;
while ( count < 3) { cout << ” Hello ” << count << endl ; count ++; }

Output :

Hello Hello Hello

C++ Part 13

Types of Control

• Selection: Execute a different instruction depending on the result of evaluating some [Boolean] condition.
• if/else, multiway if, switch, ? :
• Iteration: Repetitively execute some instruction until some condition is met.
•  for, while, do while.

Conditions

A condition is a Boolean expression - i.e., one that evaluates to true or false.
Most commonly either a relational operator or a logical combination of conditions:
Relational (Comparison) Operators:== != < > <= >=
Logical operators:! && ||

For example :  

• n <= 100 && n >= 0  // n less than equal to AND n must be greater than 0
• n< 101 && n >= 0  // n less than 101 AND n greater than equal to 0
• grade> ’c’ && grade <= ’f’ // grade greater than 'c' ( character c ) AND less than equal to 'f'
• y< x && y >= 0   //