POWERSHELL-F format operator

Today with the Netizen, the Netizen gave two lines of code, can output the following effect

1..9 | %{[email protected] ()} {$a +=$ ("{0}{1}{0}"-F ("" * (9-$_)), ("$_" * (2*$_-1))} {$a [0..8+7..0]} 1..9 | %{$a = ""}{for ($i =1; $i-le $_; $i + +) {$a + = "{0,-7}"-F "$i X $_=$ ($i *$_)"}; $a + = "' R ' n"} {$a}

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At first glance, honestly admit that I really did not understand how these two lines work, studied carefully for a while, finally understand the logical relationship.

These two lines of code mainly take advantage of PowerShell inside the use of the format operator-F.

The resources are as follows

Http://ss64.com/ps/syntax-f-operator.html

There are 2 main expressions of this operator:

Expression Form 1

"String with placeholders"-F "Array of values to place into the placeholders"

For example

Get-childitem C:\Temp | Foreach-object {' Filename: {0} Created: {1} '-F $_.fullname,$_.creationtime}

You can see that the name of filename is assigned to the FullName attribute, and created is assigned to the CreationTime property.

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Expression 2, I for position, a for space position, negative for the right plus space, positive for the left plus space, FS is some formatting options, such as hex, percentage, etc.

"{I,a:fs} {I,a:fs} {I,A:FS}:"-F "STRING0", "string1", "string2" ...

The two examples mentioned above mainly take advantage of the second form of expression. Now take a closer look.

1..9 | %{[email protected] ()} {$a +=$ ("{0}{1}{0}"-F ("" * (9-$_)), ("$_" * (2*$_-1))} {$a [0..8+7..0]}

The basic principles of the pyramid are known to count the spaces and numbers of each line, and then write loops.

First 1 to 9 passes through the pipe, and then for each number, he creates an array, {0}{1}{0} corresponds to the two strings provided, exactly the "space" + "number" + "space" format. {0} corresponds to ("" * (9-$_)), {1} corresponds to ("$_" * (2*$_-1))

Add up, $a is just the top half of the pyramid. Finally through $a[0..8] output upper half, $a [7..0] output next half ~

1..9 | %{$a = ""}{for ($i =1; $i-le $_; $i + +) {$a + = "{0,-7}"-F "$i X $_=$ ($i *$_)"}; $a + = "' R ' n"} {$a}

The idea of this example is similar. The pipe is passed in each number, listed separately, {0,-7} represents the 7 spaces to the right of the current output string; Note that in this example, the $ A created by him is an empty string, so every element added to it will not be wrapped like an array. The author adds a return line break at the end of each loop.

This article is from the "Mapo Tofu" blog, please be sure to keep this source http://beanxyz.blog.51cto.com/5570417/1774329

POWERSHELL-F format operator