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Control Flow

Control flow statements let you make decisions and repeat actions in your scripts.

if / elseif / else

The most fundamental decision structure. The condition must be wrapped in parentheses, and the body goes inside braces:

powershell

$score = 85

if ($score -ge 90) {
    "Grade: A"
} elseif ($score -ge 80) {
    "Grade: B"
} elseif ($score -ge 70) {
    "Grade: C"
} else {
    "Grade: F"
}

switch Statement

Use switch when comparing one value against many possibilities. It is cleaner than a chain of if/elseif blocks:

powershell

$day = "Monday"

switch ($day) {
    "Monday"    { "Start of the week" }
    "Friday"    { "Almost weekend!" }
    "Saturday"  { "Weekend!" }
    "Sunday"    { "Weekend!" }
    default     { "Midweek day" }
}

Key Concept: Unlike many languages, PowerShell's switch tests every case by default and does not fall through. Use break inside a case to stop after the first match.

foreach Loop

Iterates over each item in a collection:

powershell

$fruits = @("apple", "banana", "cherry")

foreach ($fruit in $fruits) {
    "I like $fruit"
}

for Loop

A counted loop with an initializer, condition, and increment:

powershell

for ($i = 0; $i -lt 5; $i++) {
    "Iteration $i"
}

while and do-while / do-until

`while` checks the condition before each iteration:

powershell

$count = 0
while ($count -lt 3) {
    "Count is $count"
    $count++
}

`do-while` always executes at least once, then checks:

powershell

$input = ""
do {
    $input = Read-Host "Enter 'quit' to exit"
} while ($input -ne "quit")

`do-until` runs until the condition becomes true (the inverse of do-while):

powershell

$num = 1
do {
    $num *= 2
} until ($num -ge 100)

break and continue

`break` exits the current loop entirely. `continue` skips the rest of the current iteration and moves to the next:

powershell

foreach ($n in 1..10) {
    if ($n -eq 3) { continue }  # skip 3
    if ($n -eq 7) { break }     # stop at 7
    $n
}
# Output: 1 2 4 5 6

Key Concept: break and continue work in foreach, for, while, do-while, and do-until loops. Inside a switch, break exits the switch statement.

Exercises

0/5 completed

Write an if/elseif/else block that checks the variable $score: if $score is greater than or equal to 90, output "A"; elseif $score is greater than or equal to 80, output "B"; else output "F".

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