preg_match如果字符串包含+或 -

Question

How to validate if a string contain either + or - ??

preg_match('[\-\+]', '(292+3)*1', $match);
print_r($match);

preg_match('[\-\+]', '(292-3)*1', $match);
print_r($match);

output

Array
(
)
Array
(
)

Answer 1

Regex must be between delimiters:

preg_match('/[-+]/', '(292+3)*1', $match);