Functions

✅ PowerShell Function Parameters

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1️⃣ Named Parameters

• Defined inside the param() block.
• You specify the parameter name when calling the function.
• Can have default values.

Example:

function Show-ParamExample {
    param(
        $Name = "Example"
    )
    "Name is $Name"
}

Usage:

Show-ParamExample
# Output: Name is Example

Show-ParamExample -Name "Pavan"
# Output: Name is Pavan

✔ If no value is given → default is used.

✔ If value is given → it overrides default.

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2️⃣ Positional Parameters

• No need to specify parameter name.
• PowerShell assigns values based on order.
• Values go into $args array if not defined in param().

Simple Example:

function Show-Positional {
    "First value: $($args[0])"
}

Usage:

Show-Positional Hello
# Output: First value: Hello

✔ First value after function name → $args[0]

✔ Second value → $args[1]

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Better Positional Example (With Param Block)

function Add-Numbers {
    param(
        $A,
        $B
    )
    $A + $B
}

Usage:

Add-Numbers 5 10
# Output: 15

Here:

• 5 → $A
• 10 → $B

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3️⃣ Switch Parameters

• Do NOT require a value.
• Either present (True) or not present (False).
• Used for flags like Verbose.

Example:

function Test-Switch {
    param(
        [switch]$Upper
    )

    if ($Upper) {
        "HELLO"
    }
    else {
        "hello"
    }
}

Usage:

Test-Switch
# Output: hello

Test-Switch -Upper
# Output: HELLO

✔ If -Upper is used → $Upper = True

✔ If not used → $Upper = False

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🎯 Quick Summary

Parameter Type	Needs Name?	Needs Value?	Example
Named	Yes	Yes	-Name "Pavan"
Positional	No	Yes	5 10
Switch	Yes	No	-Upper

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✅ PowerShell Functions & Pipeline – Simple Notes

1️⃣ Pipeline in Functions

• Any function can accept objects from the pipeline.
• Control pipeline processing using begin, process, end blocks.

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2️⃣ How begin, process, end Work

Block	When it runs	How often
begin	Before any objects come from pipeline	Once
process	For each object from pipeline	Once per object
end	After all objects are processed	Once

• Objects from pipeline → assigned to $_ automatically in process block.
• If begin/process/end are not used → all code acts like end.

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3️⃣ Simple Example

function Show-Items {
    begin {
        "Starting function..."
    }
    process {
        "Processing item: $_"
    }
    end {
        "All items processed."
    }
}

Usage:

1,2,3 | Show-Items

Output:

Starting function...
Processing item: 1
Processing item: 2
Processing item: 3
All items processed.

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4️⃣ Notes

• $_ → represents current object in process block.
• begin → initialize things (e.g., counters, variables).
• process → main work on each object.
• end → finalize (e.g., display totals, cleanup).

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5️⃣ Example Without begin/process/end

function Show-ItemsSimple {
    "Item: $_"
}

Usage:

1,2,3 | Show-ItemsSimple

Output:

Item: 1
Item: 2
Item: 3

• Here, all code is treated like end → still works, but less control.

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