4. Control Flow - Loop

Today’s Outline

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• Loop
  • while
  • do-while
  • for
• Programming styles for control flow

Loop

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while

int x, max;
max = 0;
cout << "Enter a positive integer. ";
cout << "Type 0 to quit.\\n";
cin >> x;
while (x != 0) {
    if (x > max) {
        max = x;
    }
    cout << "Enter a positive integer. ";
    cout << "Type 0 to quit.\\n";
    cin >> x;
}

do-while

int x, max;
max = 0;
 
do {
    cout << "Enter a positive integer. ";
    cout << "Type 0 to quit.\\n";
    cin >> x;
    if (x > max) {
        max = x;
    }
} while (x != 0);

• do-while is better suited for loops that require at least one iteration

for

int i; // Declare iteration variable outside
for (i = 0; i < 10; i++) {
    if (i % 2 == 0) {
        cout << i << endl;
    }
}

goto statement

int main() {
    int num;
    cin >> num;
    if (num % 2 == 0)
        goto even;
    else
        goto odd;
even:
    cout << num << " is even\\n";
    return 0;
odd:
    cout << num << " is odd\\n";
    return 0;
}

• bad programming practice
• can be replaced with break and continue

Short-Circuit Evaluation with goto

Programming styles for control flow

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• Indentation
• if Condition Style