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IterationUsing loops

in VB.NET

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Loop structures

These are used when we want lines of code to be executed many times

We might want it to run a set number of times.

We may need to check if various conditions have been met.

There are loops for all occasions and programmers have their “favourites”!

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Fixed Loop structures

If we want the loop to run a fixed number of times, we use a For…..Next loop

This will use a variable as a counter

Syntax:For first value To last value

Line of code to executeNext value

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For...Next example

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Conditional Loop Structures

If we want the loop to repeat until a condition changes (at runtime).

Use While …. End While to check the condition before running loopSyntax:

While condition = true

Line of code executeEnd While

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While…End While example

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Conditional Loop Structures

Use Do…. Loop to run until a condition becomes trueThis code will run at least once Beware! It is possible to create loops that

carry on to infinity. Press Ctrl + Break to stop, but you may lose some unsaved work

Syntax:Do

Line of code to executeLoop Until condition = true

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Do… Loop Until example

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Programming terms

When we need to repeat a set of instructions,

we have 3 options: For….Next - runs for fixed number of loops

While…End While - runs while condition is true

Do…Loop Until - runs until condition becomes

true