while and do-while Loops0%

Traditional for Loops with Multiple Counters

while and do-while Loops

Beginner11 min read•Updated: 2026-10-22

🔄 while and do-while Loops

Introduction

Loops repeat a code block until a condition evaluates to false. C++ provides entry-controlled loops (while) and exit-controlled loops (do-while).

🔁 The `while` Loop (Entry-Controlled)

The test expression is checked before entering the loop body. If the condition is initially false, the body never executes:

1#include <iostream>
2 
3int main() {
4    int counter = 1;
5    int sum = 0;
6 
7    while (counter <= 10) {
8        sum += counter;
9        ++counter;
10    }
11 
12    std::cout << "Sum of numbers 1 to 10 is: " << sum << "\n";
13    return 0;
14}

🔁 The `do-while` Loop (Exit-Controlled)

The test expression is checked after executing the body. Therefore, the body is guaranteed to run at least once:

1#include <iostream>
2 
3int main() {
4    int pin = 0;
5    constexpr int CORRECT_PIN = 1234;
6 
7    do {
8        std::cout << "Enter 4-digit Security PIN: ";
9        std::cin >> pin;
10        
11        if (pin != CORRECT_PIN) {
12            std::cout << "Incorrect PIN. Try again.\n";
13        }
14    } while (pin != CORRECT_PIN);
15 
16    std::cout << "Access Granted! Welcome to MSK Banking Portal.\n";
17    return 0;
18}

💡 Summary Comparison

Loop Type	Condition Check	Minimum Executions	Best Use Case
`while`	Entry (Before body)	0 times	When processing streams, iterating data buffers
`do-while`	Exit (After body)	1 time	Console menus, input re-prompts, games

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Traditional for Loops with Multiple Counters

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Building Interactive Console Menus with Input Validation	Traditional for Loops with Multiple Counters

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Traditional for Loops with Multiple Counters

while and do-while Loops

Beginner11 min read•Updated: 2026-10-22

Study Materials

🔄 while and do-while Loops

Introduction

Loops repeat a code block until a condition evaluates to false. C++ provides entry-controlled loops (while) and exit-controlled loops (do-while).

🔁 The `while` Loop (Entry-Controlled)

The test expression is checked before entering the loop body. If the condition is initially false, the body never executes:

1#include <iostream>
2 
3int main() {
4    int counter = 1;
5    int sum = 0;
6 
7    while (counter <= 10) {
8        sum += counter;
9        ++counter;
10    }
11 
12    std::cout << "Sum of numbers 1 to 10 is: " << sum << "\n";
13    return 0;
14}

🔁 The `do-while` Loop (Exit-Controlled)

The test expression is checked after executing the body. Therefore, the body is guaranteed to run at least once:

1#include <iostream>
2 
3int main() {
4    int pin = 0;
5    constexpr int CORRECT_PIN = 1234;
6 
7    do {
8        std::cout << "Enter 4-digit Security PIN: ";
9        std::cin >> pin;
10        
11        if (pin != CORRECT_PIN) {
12            std::cout << "Incorrect PIN. Try again.\n";
13        }
14    } while (pin != CORRECT_PIN);
15 
16    std::cout << "Access Granted! Welcome to MSK Banking Portal.\n";
17    return 0;
18}

💡 Summary Comparison

Loop Type	Condition Check	Minimum Executions	Best Use Case
`while`	Entry (Before body)	0 times	When processing streams, iterating data buffers
`do-while`	Exit (After body)	1 time	Console menus, input re-prompts, games

Next Lesson

Traditional for Loops with Multiple Counters

Continue learning with hands-on practice, examples, and exercises in the upcoming topic.

Related Lessons

Previous Lesson	Next Lesson
Building Interactive Console Menus with Input Validation	Traditional for Loops with Multiple Counters

Practice Quiz

Test your understanding of this lesson with 1 questions. Each question has one correct answer.

Previous Next

🔄 while and do-while Loops

Introduction

🔁 The while Loop (Entry-Controlled)

🔁 The do-while Loop (Exit-Controlled)

💡 Summary Comparison

Traditional for Loops with Multiple Counters

Related Lessons

Practice Quiz

Loading Page Content...

🔄 while and do-while Loops

Introduction

🔁 The while Loop (Entry-Controlled)

🔁 The do-while Loop (Exit-Controlled)

💡 Summary Comparison

Traditional for Loops with Multiple Counters

Related Lessons

Practice Quiz

🔁 The `while` Loop (Entry-Controlled)

🔁 The `do-while` Loop (Exit-Controlled)

🔁 The `while` Loop (Entry-Controlled)

🔁 The `do-while` Loop (Exit-Controlled)