Statements can be executed repeatedly in loops.
If you need to run the same statements repeatedly, you can program a loop.
If you know how many times you want to loop, you can use a for loop. This kind of loop is especially useful for counting up or counting down:
If you work with a collection or an array, you often use a for each loop.
A collection is a group of similar objects, and the for each loop lets you carry out a task on each item. The for each loop walks through a collection until it is finished.
The example below walks through the ASP.NET Request.ServerVariables collection.
The while loop is a general purpose loop.
A while loop begins with the while keyword, followed by parentheses, where you specify how long the loop continues, then a block to repeat.
While loops typically add to, or subtract from, a variable used for counting.
In the example below, the += operator adds 1 to the variable i, each time the loop runs.
An array is useful when you want to store similar variables but don't want to create a separate variable for each of them: