Regular expressions to remove space and whitespace in PHP?

I'm looking for regular expressions to remove space and whitespace 开发者_JAVA百科before and after a comma.

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Try this:

$output = preg_replace('/\s*,\s*/', ',', $str);

This will replace all commas with possible leading and trailing whitespace characters (\s) by a single comma.

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preg_replace('/\s*,\s*/', ',', $target_string);

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You don't need regex for this.

$output = explode(',', $input);
$output = array_map('trim', $output);
$output = implode(',', $output);