while Loop C++ - Learn C++ - C++ Tutorial - C++ programming
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What is Loop in C++
- Loops are used in programming to repeat a specific block of code. In this article, you will learn to create while and do...while loops in C++ programming.
- A loop statement allows us to execute a statement or group of statements multiple times
- In computer programming, loop repeats a certain block of code until some end condition is met.
- There are 3 type of loops in C++ Programming:
- for Loop
- while Loop
- do...while Loop
- In this we are going to explain while loop and do while loop
C++ while Loop
- A while loop is a control flow statement that allows code to be executed repeatedly based on a given Boolean condition.
- The while loop evaluates the test expression.
- If the test expression is true, codes inside the body of while loop is evaluated.
- Then, the test expression is evaluated again. This process goes on until the test expression is false.
- When the test expression is false, while loop is terminated.
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Syntax of a while loop
- where, testExpression is checked on each entry of the while loop.
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Flowchart of while Loop
Example 1: C++ while Loop
- In this program, user is asked to enter a positive integer which is stored in variable number. Let's suppose, user entered 4.
- Then, the while loop starts executing the code. Here's how while loop works:
- Initially, i = 1, test expression i <= number is true and factorial becomes 1.
- Variable i is updated to 2, test expression is true, factorial becomes 2.
- Variable i is updated to 3, test expression is true, factorial becomes 6.
- Variable i is updated to 4, test expression is true, factorial becomes 24.
- Variable i is updated to 5, test expression is false and while loop is terminated.
C++ do...while Loop
- The do...while loop is a variant of the while loop with one important difference.
- The body of do...while loop is executed once before the test expression is checked.
- The codes inside the body of loop is executed at least once. Then, only the test expression is checked.
- If the test expression is true, the body of loop is executed. This process continues until the test expression becomes false.
- When the test expression is false, do...while loop is terminated