For - PowerShell

Overview

The For command in PowerShell executes a series of commands repeatedly for a specified number of iterations or until a condition is met. It provides a convenient way to iterate over sequences of objects or values in a loop.

Syntax

For (<LoopVariable> in <Expression>)
{
    <Commands to execute>
}

Parameters:

  • <LoopVariable>: Name of the variable used to hold the current iteration item.
  • <Expression>: Expression that defines the sequence of values or objects to loop through.

Options/Flags

None

Examples

Example 1: Loop through a range of numbers from 1 to 10.

For ($i in 1..10)
{
    Write-Host "Number: $i"
}

Example 2: Loop through the items in an array.

$myArray = 1, 2, 3, 4, 5
For ($item in $myArray)
{
    Write-Host "Item: $item"
}

Example 3: Loop until a condition is met.

$sum = 0
For (; $sum -lt 100;)
{
    $sum += Get-Random -Maximum 10
}
Write-Host "Sum reached 100 after $sum iterations"

Common Issues

  • Infinite loop: Avoid using a condition that will never be met, leading to an infinite loop.
  • Loop variable scope: The loop variable is only visible within the loop block.
  • Array index out of bounds: Ensure the array has enough elements to iterate through.

Integration

The For command can be integrated with other PowerShell commands for more complex tasks:

  • Combine with Where-Object to filter items based on a condition.
  • Use Break or Continue to control the loop flow.
  • Nest multiple For loops for more complex iterations.
  • While: Executes commands repeatedly while a condition is met.
  • ForEach-Object: Iterates over each object in a collection.
  • ForEach: Iterates over each item in a collection and stores results.