difference between while and do while loop in c

Difference between While and Do-While Loop in C

C programming language offers two types of loop constructs to help you solve complex problems and achieve repetitive tasks in efficient ways. While and do-while loops are popular control structures used across various programming languages, and understanding the difference between them is important for writing bug-free and optimized code in C. In this article, we will discuss the key differences between while and do-while loops in C programming.

1. Syntax

While loop syntax in C:

“`
while(condition)
{
// statements to execute
}
“`
Do-while loop syntax in C:

“`
do
{
// statements to execute
}while(condition);
“`

One primary difference between these two types of loops is where the condition is evaluated. A while loop checks the condition first and then executes the loop’s body, while a do-while loop does the opposite. It executes the loop’s body first and then checks the condition.

2. Iteration Control

A while loop is a pre-test loop, meaning the condition is tested at the beginning of each iteration. If the condition is false, the loop’s body won’t execute even once.

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A do-while loop, on the other hand, is a post-test loop. This implies the loop’s body executes at least once, irrespective of the condition’s value. After the first iteration, the condition is evaluated at the end of each loop cycle, and the loop will continue executing so long as the condition remains true.

3. Typical Use Cases

While loops are ideal for operations that have a known number of iterations or that will cease eventually. They’re good for traversing an array or a linked list as the number of loops required is fixed.

Do-while loops, however, are suitable for operations that require at least one iteration before termination or must run at least once. They are typically used when the loop’s body must execute once before allowing the condition to be evaluated. A good example of when to use a do-while loop is when you prompt user input; you would like the user to input data at least once, irrespective of whether the input is valid or not.

Conclusion

Both while and do-while loops are critical control structures that help programmers iterate and execute a block of code repetitively based on the condition’s value. While they differ slightly in syntax and the way the loop body is executed, each type of loop has unique benefits and use cases. Understanding the differences between the two and their appropriate uses can help C programmers to write more efficient, robust and maintainable code for their projects.

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Table difference between while and do while loop in c

While Loop Do While Loop
A while loop checks the condition before executing the code inside the loop A do while loop executes the code inside the loop at least once before checking the condition
If the condition is false, the loop may not execute at all The code inside the loop is guaranteed to execute at least once
The syntax for a while loop is:
while(condition){
     // code to be executed
}
The syntax for a do while loop is:
do{
     // code to be executed
}while(condition);