difference between while loop and do while loop

Difference between while loop and do while loop

When it comes to programming, loops are one of the most important concepts to understand. They help in executing a block of code repeatedly until a certain condition is met. Two of the most commonly used loops are the while loop and the do-while loop. Although they are similar in some ways, there are significant differences between them. In this article, we will explore these differences.

The while loop

The while loop is a type of loop that checks the condition first and then executes the code inside the loop. The condition can be any logical expression that evaluates to either true or false. If the condition is false, the loop will not execute at all. Here is an example of a while loop:

“`
while (condition) {
// code to be executed
}
“`

The while loop will continue to execute the code inside as long as the condition is true. Once the condition becomes false, the loop will exit immediately, and the code execution will continue from the next statement after the loop.

The do-while loop

The do-while loop is a type of loop that executes the code first and then checks the condition. This means that the code inside the loop will always execute at least once, regardless of whether the condition is true or false. Here is an example of a do-while loop:

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“`
do {
// code to be executed
} while (condition)
“`

The do-while loop will execute the code inside and continue to do so as long as the condition is true. Once the condition becomes false, the loop will exit and the execution will continue from the next statement after the loop.

Differences between while loop and do-while loop

Although both loops may seem similar, there are some differences between them:

  • The while loop checks the condition first before executing the code, while the do-while loop executes the code first and checks the condition later.
  • The while loop may not execute the code at all if the initial condition is false, while the do-while loop will execute the code at least once, regardless of the initial condition.
  • The while loop is best used when the number of iterations is unknown in advance, while the do-while loop is best used when the code needs to execute at least once before verifying the condition.

In conclusion, understanding the differences between the while loop and the do-while loop is important, as it can help you choose the right loop for your programming requirements. While both loops can be used interchangeably in certain situations, using the right loop at the right time can help you write more efficient code.

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Table difference between while loop and do while loop

While Loop Do While Loop
A while loop is a control statement that executes a block of code repeatedly until the specified condition becomes false. A do while loop is a control statement that executes a block of code first, and then checks the condition repeatedly until the specified condition becomes false.
The condition is tested at the beginning of each iteration. The condition is tested at the end of each iteration.
If the condition is false initially, the block of code inside the while loop will never be executed. The block of code inside the do while loop will be executed at least once, even if the condition is false initially.
If the condition is false at any time, the code inside the while loop will be skipped. If the condition is false at any time after the first iteration, the code inside the do while loop will be skipped.
The while loop structure is more common and widely used. The do while loop structure is less common and less widely used.