php警告：preg_match（）[function.preg-match]：第71行的/sample.php中的未知修饰符'['[重复]

Question

This question already has an answer here:

• Warning: preg_replace(): Unknown modifier ']' 3 answers

I am getting the error:

Warning: preg_match() [function.preg-match]: Unknown modifier '[' in /sample.php on line 71

Every time I'm try to run my script.

The code at line 71 is:

if(!preg_match("[h][t][t][p][:][/][/][a-zA-Z0-9\]",$link))

Please help me in fixing this issue..

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Answer 1

You need delimiters and few modifications in pattern:

preg_match("/http:\/\/[a-zA-Z0-9\\\\]/",$link)

1. Missing delimeters for pattern : /pattern/
2. No need of too many [ ]
3. If you need \, you should escape with \ so \\\\ [Read this SO answer to know why you need three backslash to escape a backslash]