# Looping With a Known Loop Count

Just do something 5 times.

## Loops With a Known Loop Count¶

• A very common looping task in programming is to loop a predetermined amount of times.

• We can code this with `while` loops or `for` loops. They are all equivalent in functionality. However, programmers tend to favor the `for` loop for this.

• Let's look at it with the `while` loop first then the `for`.

• Here's a small program that does something exactly 5 times.

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22``` ``````/* This function is in file unit04/demos/js/knownLoopCount.js. It loops five times with a while loop */ function whileFiveTimes() { "use strict"; // Declare Constants const INITIAL_VALUE = 0; const LOOP_LIMIT = 5; // Declare Variables let counter; // Initialize the counter counter = INITIAL_VALUE; while (counter < LOOP_LIMIT) { document.write("This is loop number: " + counter + "
"); counter++; } } ``````
```
whileFiveTimes();

```
• And here it is with a `for` loop.
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18``` ``````/* This function is in file unit04/demos/js/knownLoopCount.js. It loops five times with a for loop */ function forFiveTimes() { "use strict"; // Declare Constants const INITIAL_VALUE = 0; const LOOP_LIMIT = 5; // Declare Variables let counter; for (counter = INITIAL_VALUE; counter < LOOP_LIMIT; counter++) { document.write("This is loop number: " + counter + "
"); } } ``````
```
forFiveTimes();

```

##### They look very similar. The main difference is that the `for` loop has one less line of code.¶ ##### The `while` loop does the same thing, only differently.¶ ## Example: Fahrenheit-Celsius Conversion¶

Demo

1. Demo: Fahrenheit-Celsius Conversion
• unit04/demos/demo-fahrenheit-celsius.html

Not everything that can be counted counts, and not everything that counts can be counted. -Albert Einstein

Labs

1. Lab05: While Loop with known Count
• unit04/labs/lab-05-while-known-count.html
2. Lab06: For Loop with known Count
• unit04/labs/lab-06-for-known-count.html

Exercises

1. Lab05 exercise
• unit04/exercises/exercise-05.html
2. Lab06 exercise
• unit04/exercises/exercise-06.html