Difference Between While and Do While
Introduction
While and do while are two common loop constructs in programming. They are used to repeat a set of instructions until a certain condition is met. However, there are some key differences between the two that every programmer should be aware of. In this article, we’ll explore these differences and provide examples of when to use while and do while loops.
While Loop
A while loop is a basic loop construct that repeats a set of instructions while a certain condition is true. The structure of a while loop looks like this:
“`
while (condition) {
// instructions to be executed
}
“`
The condition is checked at the beginning of each iteration. If the condition is true, the instructions inside the loop are executed. Once the instructions are completed, the condition is checked again. This process repeats until the condition is false.
Here’s an example of a while loop in action:
“`
let i = 0;
while (i < 5) { console.log(i); i++; } ``` This loop will print the numbers 0 through 4 to the console, because the condition `i < 5` is true for those values of `i`. Once `i` reaches 5, the condition is false and the loop stops.
Do While Loop
A do while loop is similar to a while loop, but with one key difference: the instructions inside the loop are always executed at least once, even if the condition is initially false. The structure of a do while loop looks like this:
“`
do {
// instructions to be executed
} while (condition);
“`
The instructions inside the loop are executed before the condition is checked. If the condition is true, the loop continues and the instructions are executed again. If the condition is false, the loop stops.
Here’s an example of a do while loop in action:
“`
let i = 0;
do {
console.log(i);
i++;
} while (i < 5);
```
This loop will print the numbers 0 through 4 to the console, just like the while loop. However, even if `i` started out as 5 or higher, the first iteration of the loop would still execute and print the number 0.
When to Use While vs. Do While
The decision to use a while loop vs. a do while loop depends on the specific requirements of your program. Here are some guidelines to follow:
– Use a while loop if you want the instructions to be executed only if the initial condition is true.
– Use a do while loop if you want the instructions to be executed at least once, even if the initial condition is false.
– Be careful when using a do while loop, as it can result in an infinite loop if the condition is never true.
Conclusion
While and do while loops are two loop constructs that every programmer should be familiar with. While loops repeat a set of instructions while a certain condition is true, and do while loops do the same but with the instructions always executed at least once. By understanding the differences between these two constructs, you’ll be better equipped to choose the right one for your program.
Table difference between while and do while
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