使用PHP preg_match

Question

I need to find a specic line of text, from several lines of text

So, I have a text file with several lines of text, eg:

JOHN
MIKE
BEN
*BJAMES
PETE

I read that contents into an array, with each line of text, placed into a seperate element of the array.

I then tested each element of the array, to find the line that starts with, say: *B

ie:

if ( preg_match( "/^\*(B)/",$contents[$a] ) )

why dosnt that work ?

Answer 1

Consider the following code:

$regex = "%\*B(.*?)%is"; 

if (preg_match($regex, $contents[a]))  {  /// do something }

Also you may find this slide very helpful for learning regular expressions:

http://www.addedbytes.com/cheat-sheets/regular-expressions-cheat-sheet/

Answer 2

I wouldn't use double quotes here, because \\ is an escape sequence:

if ( preg_match( '/^\*(B)/',$contents[$a] ) )

It works here for me though even with double quotes, so you might want to check what $contents[$a] is:

$myline = "*BJAMES";
if( preg_match( "/^\*(B)/", $myline) )
{
  echo "Yes\n";
}

Answer 3

The following works for me (where $txt is your original data):

foreach ( explode("\n", $txt) as $a ) {
    if ( preg_match( "/^\*B/", $a ) ) {
        echo "**MATCH " . $a . "<br/>";
    }
}