Don't Concatenate Strings

I really dislike string concatenation. It's like forcing someone to cuddle with someone they don't even know. Rude.

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And completely unnecessary, when you use double quotes.

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Same end effect. In double quotes, PowerShell will look for the $ character. When it finds it:

1. If the next character is a { then PowerShell will take everything to the matching } as a variable name, and replace the whole thing with that variable's contents. For example, putting ${my variable} inside double quotes will replace that with the contents of ${my variable}.

2. If the next character is a ( then PowerShell will take everything to the matching ) and execute it as code. So, I executed $wmi.serialnumber to access the serialnumber property of whatever object was in the $wmi variable.

3. Otherwise, PowerShell will take every character that is legal for a variable name, up until the first illegal variable name character, and replace it with that variable. That's how $computer works in my example. The space after r isn't legal for a variable name, so PowerShell knows the variable name stops at r.

There's a sub-gotcha here:

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This won't work as expected. In most cases, $wmi will be replaced by an object type name, and .serialnumber will still be in there. That's because . isn't a legal variable name character, so PowerShell stops looking at the variable with the letter i. It replaces $wmi with its contents. You see, in the previous example, I'd put $($wmi.serialnumber), which is a subexpression, and which works. The parentheses make their contents execute as code.