使用正则表达式确定提交时的空值

Question

我有这个字符串

"fname=Nerison&mname=Sayson&lname=Pitogo&extname=&email=son2xp2go04221%40gmail.com&bday=1991-01-04&gender=MALE&address=Libertad%2C+Butuan+City"

使用正则表达式，如何确定除了扩展名之外还有空值？

Answer 1

使用这个简单的正则表达式：

\b(?!extname)\w+=(?:&|$)

请参阅demo，它匹配两个空变量，但不匹配extname

解释正则表达式

\b                       # the boundary between a word char (\w) and
                         # something that is not a word char
(?!                      # look ahead to see if there is not:
  extname                #   'extname'
)                        # end of look-ahead
\w+                      # word characters (a-z, A-Z, 0-9, _) (1 or
                         # more times (matching the most amount
                         # possible))
=                        # '='
(?:                      # group, but do not capture:
  &                      #   '&'
 |                       #  OR
  $                      #   before an optional \n, and the end of
                         #   the string
)                        # end of grouping