Problem Solving and Structured Programming, Slides of Advanced Computer Programming

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Chapter 9

Additional

Control

Structures

Chapter 9 Topics

• Switch Statement for Multi-Way Branching
• Do-While Statement for Looping
• For Statement for Looping
• Using break and continue Statements

4

float weightInPounds = 165.8; char weightUnit;

... // User enters letter for desired weightUnit switch (weightUnit) { case „P‟ : case „p‟ : cout << weightInPounds << “ pounds “ << endl; break; case „O‟ : case „o‟ : cout << 16.0 * weightInPounds << “ ounces “ << endl; break; case „K‟ : case „k‟ : cout << weightInPounds / 2.2 << “ kilos “ << endl; break; case „G‟ : case „g‟ : cout << 454.0 * weightInPounds << “ grams “ << endl; break; default : cout << “That unit is not handled! “ << endl; break; } 4

Switch Statement

• The value of IntegralExpression (of char, short, int,

long or enum type) determines which branch is

executed

• Case labels are constant (possibly named) integral

expressions

• Several case labels can precede a statement

Do-While Statement

Do-While is a looping control structure in which the loop condition is tested after each iteration of the loop

SYNTAX

do { Statement

} while ( Expression );

Loop body statement can be a single statement or a block

8

void GetYesOrNo (/* out */ char& response) // Inputs a character from the user // Postcondition: response has been input // && response == „y‟ or „n‟ { do { cin >> response; // Skips leading whitespace if ((response != „y‟) && (response != „n‟)) cout << “Please type y or n : “; } while ((response != „y‟) && (response != „n‟)); }

Example of Do-While

8

Do-While Loop

When the expression is tested and found to be false, the loop is exited and control passes to the statement that follows the Do-while statement (^) 10

Statement

Expression

DO

WHILE

FALSE

TRUE

For Loop

SYNTAX

for ( initialization; test expression; update )

Zero or more statements to repeat

Example of For Loop

int num;

for (num = 1; num <= 3; num++)

{

cout << num << “Potato” << endl;

}

Example of Repetition

int num;

for (num = 1; num <= 3; num++) cout << num << “Potato” << endl;

14

num

OUTPUT

Example of Repetition

int num;

for(num = 1; num <= 3; num++)

cout << num << “Potato” << endl;

16

num

OUTPUT

true

Example of Repetition

int num;

for (num = 1; num <= 3; num++)

cout << num << “Potato” << endl;

17

num

OUTPUT

1Potato

Example of Repetition

int num;

for(num = 1; num <= 3; num++)

cout << num << “Potato” << endl;

19

num

OUTPUT

true

1Potato

Example of Repetition

int num;

for (num = 1; num <= 3; num++)

cout << num << “Potato” << endl;

20

num

OUTPUT

1Potato

2Potato