PHP Regex获取参数值

Question

Technically I need to implement parse_str() using regex. Though I will only extract one parameter value from a query. I have a string like a=val1&b=val2&c=val3

is it possible to get only the value of say b using preg_match also assuming b can be the last query (means the string can also be a=val1&b=val2 )?

Answer 1

Seems simple enough:

/(?:^|&)b=([^&]*)/

The value you want will be in the first capture group.