What are ^.* and .*$ in regular expressions?

Question

Can someone explain the meaning of these characters. I\'ve looked them up but I don\'t seem to get it.

The whole regular expression is:

/^.*(?=.{8,})(?=.         


        

Answer 1

Main docs: http://www.php.net/manual/en/reference.pcre.pattern.syntax.php

/^.*(?=.{8,})(?=.*[a-z])(?=.*[A-Z])(?=.*[@#$%^&+=]).*$/
12345   6         7                                  89

1 - start of pattern, can be almost any character, and must have a matching character at the END of the pattern (see #9 below)
2 - anchors the pattern to the start of a line of text
3 - `.` matches any character
4 - a modifier, "0 or more of whatever came before"
  - `.*` means "0 or more of ANY characters"
5 - A positive lookahead assertion: http://www.php.net/manual/en/regexp.reference.assertions.php
6 - A repetition indictor: http://www.php.net/manual/en/regexp.reference.repetition.php
  - `{8,}` = "at least 8 of whatever came previously"
  - `.{8,}` = "at least 8 'any' characters"
7 - A character class: http://www.php.net/manual/en/regexp.reference.character-classes.php
  - `[a-z]` - any one character in the range 'a' - 'z' (the lower case alphabet)
8 - anchors the pattern to the end of the line
9 - end of the pattern, must match character used in #1 above.