正则表达式：区分'name'和'name_local'

How to make regex select strictly

'name' : if searching for 'name',

'name_local' : if searching for 'name_local',

but not to select both if searching for 'name'?

Tried '/('.$key.')(?!_)/', but it still selects both 'name' and 'name_local' if the $key is name.

You need word boundary anchor \b:

'/(\b'.$key.'\b)/'

Word boundaries don't guarantee matching right piece of input string if for example the very next character isn't a word character e.g. name-local. Use lookarounds:

(?<!\S)name(?!\S)

PHP:

$re = "/(?<!\S)$key(?!\S)/";