For loop vs While loop: Difference and Comparison

The ‘for’ loop is used only when the number of iterations is already known. The ‘while’ loop is used when the number of iterations is unknown beforehand.

Computers work on High-level languages such as C, C++, Java, Python, etc. Computer languages assist us in getting results that are difficult to obtain manually.

These high-level languages operate on a defined structure of commands. One of the basic structures of commands used in high-level languages is ‘Loops’.

A loop is a command that tends to repeat itself to obtain the desired result. In other words, a programming command that repeats itself the known number of times or the unknown number of times to fulfil certain conditions is defined as a loop.

There are various loops, such as for loop, while loop, if loop, if-else loop, if-else-if loop, etc. But the most commonly used loops are for and while loops.

Key Takeaways

1. “For loops” are used when the number of iterations is known in advance, providing a specific starting point, ending point, and increment for the loop counter.
2. While loops are used when the number of iterations is not predetermined, and the loop continues to execute as long as a given condition remains true.
3. Both loops and while loops are used to execute a block of code repeatedly, but the choice between them depends on whether the number of iterations is known or based on a specific condition.

For loop vs While loop

The difference between for loop and a while loop is that in for loop, the number of iterations to be done is already known and is used to obtain a certain result. In a while loop, the command runs until a particular condition is reached, and the statement is proved to be false.

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Comparison Table

Parameter of Comparison	For loop	While loop
Command	The structure of for loop is – for(initial condition; number of iterations){//body of the loop }	The structure of the while loop is- While(condition){statements;//body}
Iterations	Iterates for a preset number of times.	Iterates till a condition is met.
Condition	Without a condition, the loop iterates an infinite number of times until it reaches the break command.	In the absence of a condition, while loop shows an error.
Initialization	Initialization in for loop is done only once when the program starts.	Initialization is done every time the loop is iterated.
Use	Used to obtain the result only when the number of iterations is known.	Used to satisfy the condition when the number of iterations is unknown.

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What is For loop?

A loop in which the control statement is executed a pre-known number of times to obtain the result is known as the for a loop. It can be said that for loop is a repetitive command.

In for loop, the command is controlled by a variable. Each time the loop iterates, the predefined variable gets a new value.

For loop is a set of three segments-       

1. Initialization
2. Condition
3. Updation

During the initialization of the loop, a starting value for the variable will be declared. This loop requires initialization only once.

After initialization, the compiler checks whether the condition is actual or not; if it is true, the loop continues to iterate until the predefined number of iterations is obtained.

 

What is While loop?

A while loop is when the command iterates an uncertain number of times until the condition is proper. Once the condition is proved false, the iteration of the command stops.

Initialization in the while loop is made each time the loop iterates. The compiler checks the condition, and if it is proved false, the loop jumps to the next statement.

A while loop works on the following syntax–   

1.  While(condition){
2. //code
3. //loop body} 

If the while loop’s starting condition is missing, it iterates infinitely. In the while loop, no new value is created for the variable; only the condition is satisfied.

In the while loop, the condition is checked before iteration therefore, it is also known as the pre-test loop.

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Main Differences Between For loop and While loop

1. In for loop, the number of iterations to be conducted is already known, whereas, in the loop, the number of iterations is unknown.
2. For loop contains only a single condition, whereas a loop may contain a set of commands to be executed together.
3. In for loop, the initialization of the command is done only once, but in a while loop, initialization of the command is needed each time the iteration of the command is done.
4. If the condition is absent in for loop, the loop iterates an infinite number of times, whereas the while loop shows an error in case of the absence of the condition.
5. For loop can be used only in case of a known number of iterations, whereas a loop is used only when the number of iterations is unknown.

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References

1. https://link.springer.com/chapter/10.1007/11589990_144
2. https://www.date-conference.com/proceedings-archive/PAPERS/2011/DATE11/PDFFILES/06.6_1.PDF

Last Updated : 11 June, 2023