Additional Control Structures

	The switch statement – an alternative for multiway branches.
	The do-while statement – an alternative for looping.
	The for statement – another alternative for looping.
	The break and continue statements – break and continue are to a control structure as return is to a function.

The switch Statement
(A Template)

	switch (letter)
	{
	case ‘X’: Statement1;
	break;
	case ‘L’:
	case ‘M’: Statement2;
	break;
	case ‘S’: Statement3;
	break;
	default : Statement4;
	}
	Statement5;

The switch Statement
(An Example)

	switch (grade)
	{
	case ‘A’:
	case ‘B’: cout << “Good Work”;
	break;
	case ‘C’: cout << “Average Work”;
	break;
	case ‘D’:
	case ‘F’: cout << “Poor Work”;
	numberInTrouble++;
	break;
	}

The switch Statement
(An Incorrect Example, grade = ‘C’)

	switch (grade)
	{
	case ‘A’:
	case ‘B’: cout << “Good Work”;
	case ‘C’: cout << “Average Work”;
	case ‘D’:
	case ‘F’: cout << “Poor Work”;
	numberInTrouble++;
	default : cout << grade << “ is not a valid letter”
	<< “ grade;
	}

The switch Statement
(An Incorrect Example, grade = ‘C’)

	switch (grade)
	{
	case ‘A’:
	case ‘B’: cout << “Good Work”;
	case ‘C’: cout << “Average Work”;
	case ‘D’:
	case ‘F’: cout << “Poor Work”;
	numberInTrouble++;
	default : cout << grade << “ is not a valid letter”
	<< “ grade;
	}

The switch Statement
(An Incorrect Example, grade = ‘C’)

	switch (grade)
	{
	case ‘A’:
	case ‘B’: cout << “Good Work”;
	case ‘C’: cout << “Average Work”;
	case ‘D’:
	case ‘F’: cout << “Poor Work”;
	numberInTrouble++;
	default : cout << grade << “ is not a valid letter”
	<< “ grade;
	}

The switch Statement
(An Incorrect Example, grade = ‘C’)

	switch (grade)
	{
	case ‘A’:
	case ‘B’: cout << “Good Work”;
	case ‘C’: cout << “Average Work”;
	case ‘D’:
	case ‘F’: cout << “Poor Work”;
	numberInTrouble++;
	default : cout << grade << “ is not a valid letter”
	<< “ grade;
	}

The switch Statement
(An Incorrect Example, grade = ‘C’)

	switch (grade)
	{
	case ‘A’:
	case ‘B’: cout << “Good Work”;
	case ‘C’: cout << “Average Work”;
	case ‘D’:
	case ‘F’: cout << “Poor Work”;
	numberInTrouble++;
	default : cout << grade << “ is not a valid letter”
	<< “ grade;
	}

The switch Statement
(An Incorrect Example, grade = ‘C’)

	switch (grade)
	{
	case ‘A’:
	case ‘B’: cout << “Good Work”;
	case ‘C’: cout << “Average Work”;
	case ‘D’:
	case ‘F’: cout << “Poor Work”;
	numberInTrouble++;
	default : cout << grade << “ is not a valid letter”
	<< “ grade;
	}

The switch Statement
(An Incorrect Example, grade = ‘C’)

	switch (grade)
	{
	case ‘A’:
	case ‘B’: cout << “Good Work”;
	case ‘C’: cout << “Average Work”;
	case ‘D’:
	case ‘F’: cout << “Poor Work”;
	numberInTrouble++;
	default : cout << grade << “ is not a valid letter”
	<< “ grade;
	}

The do-while Statement

	DoWhileStatement
	do
	Statement
	while (Expression);
	Example
	do
	{
	cout << “Enter your age: ” ;
	cin >> age;
	if (age <= 0)
	cout << “Your age must be positive.” << endl;
	} while (age <= 0);

The for Statement

	ForStatement
	For (InitStatement Expression1; Expression2)
	Statement
	Example
	for (lastNum = 1; lastNum <= 7; lastNum++)
	{
	for (numtoPrint = 1; numtoPrint <= lastNum; numToPrint++)
	cout << numToPrint;
	cout << endl;
	}
	Note: The InitStatement can be the null statement and the two Expressions are optional.

The break and
continue Statements

	The break statement causes an immediate exit from the innermost switch, while, do-while, or for statement in which it appears.
	If break is in a loop that is nested inside another loop, control exits the inner loop but not the other.
	A continue statement terminates only the current iteration of a loop (not the whole loop).

An Example Using
break and continue

	loopCount = 1;
	while (true)
	{
	cin >> num1;
	if (!cin || num1 >= 100)
	continue;
	if (!cin || num2 <= 50)
	continue;
	cout << sqrt(float(num1 + num2)) << endl;
	loopCount++
	if (loopCount > 10)
	break;
	}

An Example Using break
and continue (num1 = 200, num2 = 55)

	loopCount = 1;
	while (true)
	{
	cin >> num1;
	if (!cin || num1 >= 100)
	continue;
	if (!cin || num2 <= 50)
	continue;
	cout << sqrt(float(num1 + num2)) << endl;
	loopCount++
	if (loopCount > 10)
	break;
	}

An Example Using break
and continue (num1 = 200, num2 = 55)

	loopCount = 1;
	while (true)
	{
	cin >> num1;
	if (!cin || num1 >= 100)
	continue;
	if (!cin || num2 <= 50)
	continue;
	cout << sqrt(float(num1 + num2)) << endl;
	loopCount++
	if (loopCount > 10)
	break;
	}

An Example Using break
and continue (num1 = 200, num2 = 55)

	loopCount = 1;
	while (true)
	{
	cin >> num1;
	if (!cin || num1 >= 100)
	continue;
	if (!cin || num2 <= 50)
	continue;
	cout << sqrt(float(num1 + num2)) << endl;
	loopCount++
	if (loopCount > 10)
	break;
	}

An Example Using break
and continue (num1 = 200, num2 = 55)

	loopCount = 1;
	while (true)
	{
	cin >> num1;
	if (!cin || num1 >= 100)
	continue;
	if (!cin || num2 <= 50)
	continue;
	cout << sqrt(float(num1 + num2)) << endl;
	loopCount++
	if (loopCount > 10)
	break;
	}

An Example Using break
and continue (num1 = 200, num2 = 55)

	loopCount = 1;
	while (true)
	{
	cin >> num1;
	if (!cin || num1 >= 100)
	continue;
	if (!cin || num2 <= 50)
	continue;
	cout << sqrt(float(num1 + num2)) << endl;
	loopCount++
	if (loopCount > 10)
	break;
	}

An Example Using break
and continue (num1 = 200, num2 = 55)

	loopCount = 1;
	while (true)
	{
	cin >> num1;
	if (!cin || num1 >= 100)
	continue;
	if (!cin || num2 <= 50)
	continue;
	cout << sqrt(float(num1 + num2)) << endl;
	loopCount++
	if (loopCount > 10)
	break;
	}

An Example Using break
and continue (num1 = 200, num2 = 55)

	loopCount = 1;
	while (true)
	{
	cin >> num1;
	if (!cin || num1 >= 100)
	continue;
	if (!cin || num2 <= 50)
	continue;
	cout << sqrt(float(num1 + num2)) << endl;
	loopCount++
	if (loopCount > 10)
	break;
	}

Example Using break and continue (num1 = 2, num2 = 55, loopCount = 15)

	loopCount = 1;
	while (true)
	{
	cin >> num1;
	if (!cin || num1 >= 100)
	continue;
	if (!cin || num2 <= 50)
	continue;
	cout << sqrt(float(num1 + num2)) << endl;
	loopCount++
	if (loopCount > 10)
	break;
	}

Example Using break and continue (num1 = 2, num2 = 55, loopCount = 15)

	loopCount = 1;
	while (true)
	{
	cin >> num1;
	if (!cin || num1 >= 100)
	continue;
	if (!cin || num2 <= 50)
	continue;
	cout << sqrt(float(num1 + num2)) << endl;
	loopCount++
	if (loopCount > 10)
	break;
	}

Example Using break and continue (num1 = 2, num2 = 55, loopCount = 15)

	loopCount = 1;
	while (true)
	{
	cin >> num1;
	if (!cin || num1 >= 100)
	continue;
	if (!cin || num2 <= 50)
	continue;
	cout << sqrt(float(num1 + num2)) << endl;
	loopCount++
	if (loopCount > 10)
	break;
	}

Example Using break and continue (num1 = 2, num2 = 55, loopCount = 15)

	loopCount = 1;
	while (true)
	{
	cin >> num1;
	if (!cin || num1 >= 100)
	continue;
	if (!cin || num2 <= 50)
	continue;
	cout << sqrt(float(num1 + num2)) << endl;
	loopCount++
	if (loopCount > 10)
	break;
	}

Example Using break and continue (num1 = 2, num2 = 55, loopCount = 15)

	loopCount = 1;
	while (true)
	{
	cin >> num1;
	if (!cin || num1 >= 100)
	continue;
	if (!cin || num2 <= 50)
	continue;
	cout << sqrt(float(num1 + num2)) << endl;
	loopCount++
	if (loopCount > 10)
	break;
	}

Example Using break and continue (num1 = 2, num2 = 55, loopCount = 15)

	loopCount = 1;
	while (true)
	{
	cin >> num1;
	if (!cin || num1 >= 100)
	continue;
	if (!cin || num2 <= 50)
	continue;
	cout << sqrt(float(num1 + num2)) << endl;
	loopCount++
	if (loopCount > 10)
	break;
	}

Example Using break and continue (num1 = 2, num2 = 55, loopCount = 15)

	loopCount = 1;
	while (true)
	{
	cin >> num1;
	if (!cin || num1 >= 100)
	continue;
	if (!cin || num2 <= 50)
	continue;
	cout << sqrt(float(num1 + num2)) << endl;
	loopCount++
	if (loopCount > 10)
	break;
	}

Example Using break and continue (num1 = 2, num2 = 55, loopCount = 15)

	loopCount = 1;
	while (true)
	{
	cin >> num1;
	if (!cin || num1 >= 100)
	continue;
	if (!cin || num2 <= 50)
	continue;
	cout << sqrt(float(num1 + num2)) << endl;
	loopCount++
	if (loopCount > 10)
	break;
	}

Guidelines for Choosing
a Looping Statement

	For count-controlled loops, think for.
	If you know it will execute at least once, do-while is good for event control.
	If you don’t know whether the loop will ever execute, use a pretest loop (while or for).
	When in doubt, use a while statement.

Testing and Debugging Hints

	Put a break statement at the end of each case alternative in a switch statement.
	Case labels in a switch statement are made up of values, not variables.
	A switch expression cannot be a floating-point or string expression.
	A for loop must have semicolons, whether the expressions exist or not.