[maddude]

hey guys i got this thing i need help with im using phps function:

PHP Code:

preg_match 

and i want to know what all the symbols are and what their used for could you help guys?.

[DetroitGuy]

http://us2.php.net/manual/en/function.preg-match.php

[maddude]

that doesnt explain symbols like "[" and "^" and stuff used in preg_match just its use.

[End User]

Originally Posted by maddude

that doesnt explain symbols like "[" and "^" and stuff used in preg_match just its use.

Modifiers
i case-insensitive pattern matching.
g global replace, or replace all
m Treat string as multiple lines. That is, change ``^'' and ``$'' from matching at only the very start or end of the string to the start or end of any line anywhere within the string
s Treat string as single line. That is, change ``.'' to match any character whatsoever, even a newline, which it normally would not match.
x Extend your pattern's legibility by permitting whitespace and comments.

Special Characters
The following should be escaped if you are trying to match that character

\ ^ . $ | ( ) [ ]
* + ? { } ,

Special Character Definitions
\ Quote the next metacharacter
^ Match the beginning of the line
. Match any character (except newline)
$ Match the end of the line (or before newline at the end)
| Alternation
() Grouping
[] Character class
* Match 0 or more times
+ Match 1 or more times
? Match 1 or 0 times
{n} Match exactly n times
{n,} Match at least n times
{n,m} Match at least n but not more than m times
More Special Character Stuff
\t tab (HT, TAB)
\n newline (LF, NL)
\r return (CR)
\f form feed (FF)
\a alarm (bell) (BEL)
\e escape (think troff) (ESC)
\033 octal char (think of a PDP-11)
\x1B hex char
\c[ control char
\l lowercase next char (think vi)
\u uppercase next char (think vi)
\L lowercase till \E (think vi)
\U uppercase till \E (think vi)
\E end case modification (think vi)
\Q quote (disable) pattern metacharacters till \E
Even More Special Characters
\w Match a "word" character (alphanumeric plus "_")
\W Match a non-word character
\s Match a whitespace character
\S Match a non-whitespace character
\d Match a digit character
\D Match a non-digit character
\b Match a word boundary
\B Match a non-(word boundary)
\A Match only at beginning of string
\Z Match only at end of string, or before newline at the end
\z Match only at end of string
\G Match only where previous m//g left off (works only with /g)

[maddude]

but what if i dont know how many letters a variable is in length, how do i use preg_match to make sure some characters are certain type and the rest are a certain type, without knowing how many characters are in the string.

[maddude]

well? any help?

[darkfreak]

Give us an example.

[End User]

Originally Posted by maddude

but what if i dont know how many letters a variable is in length, how do i use preg_match to make sure some characters are certain type and the rest are a certain type, without knowing how many characters are in the string.

If you looked at what I posted you'd probably have an idea already.

The "+" and "*" match 1 or more or none or more, respectively. The "." matches any character. If you have a string like:

<title>some text here</title>

You can match on the text between the tags like this:

<title>(.*)</title>

That will match anything or nothing. To match only if there is some text there (at least one char), you could do this:

<title>(.+)</title>

Want to match a number? Do this: \d
Match 5 numbers, a dash, and two more numbers? Do this: \d\d\d\d\d-\d\d

Match a to z and 1 to 9: [A-Za-z1-9]

Look the list over and experiment. There's also tons of stuff on the net about regular expressions.

[darkfreak]

http://www.regexplib.com

[maddude]

Originally Posted by End User

Modifiers
i case-insensitive pattern matching.
g global replace, or replace all
m Treat string as multiple lines. That is, change ``^'' and ``$'' from matching at only the very start or end of the string to the start or end of any line anywhere within the string
s Treat string as single line. That is, change ``.'' to match any character whatsoever, even a newline, which it normally would not match.
x Extend your pattern's legibility by permitting whitespace and comments.

Special Characters
The following should be escaped if you are trying to match that character

\ ^ . $ | ( ) [ ]
* + ? { } ,

Special Character Definitions
\ Quote the next metacharacter
^ Match the beginning of the line
. Match any character (except newline)
$ Match the end of the line (or before newline at the end)
| Alternation
() Grouping
[] Character class
* Match 0 or more times
+ Match 1 or more times
? Match 1 or 0 times
{n} Match exactly n times
{n,} Match at least n times
{n,m} Match at least n but not more than m times
More Special Character Stuff
\t tab (HT, TAB)
\n newline (LF, NL)
\r return (CR)
\f form feed (FF)
\a alarm (bell) (BEL)
\e escape (think troff) (ESC)
\033 octal char (think of a PDP-11)
\x1B hex char
\c[ control char
\l lowercase next char (think vi)
\u uppercase next char (think vi)
\L lowercase till \E (think vi)
\U uppercase till \E (think vi)
\E end case modification (think vi)
\Q quote (disable) pattern metacharacters till \E
Even More Special Characters
\w Match a "word" character (alphanumeric plus "_")
\W Match a non-word character
\s Match a whitespace character
\S Match a non-whitespace character
\d Match a digit character
\D Match a non-digit character
\b Match a word boundary
\B Match a non-(word boundary)
\A Match only at beginning of string
\Z Match only at end of string, or before newline at the end
\z Match only at end of string
\G Match only where previous m//g left off (works only with /g)

right so how exactly do i say it must have only 1 A-Z character in between <title> and </title> tags. and no other characters in between.