PHP RegEx: With Meta Characters

Submitted by ronard on Friday, March 21, 2014 - 21:55.

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In our last tutorials regarding ReGex we have some simple pattern of matching. We also use caret (^) For matching at the beginning of the string and (\z) to match at the end of the string. These characters are called Meta Characters and shown below. a. . (Full stop) b. ^ (Carat) c. * (Asterix) d. + (Plus) e. ? (Question Mark) f. { (Opening curly brace) g. [ (Opening brace) h. ] (Closing brace) i. \ (Backslash) g. | (Pipe) k. ( (Opening parens) l. ) (Closing parens) m. } (Closing curly brace) Above characters are very useful in terms of ReGex. But if you search a character that include with special character of Meta Characters. Then we need to escape it using backslash. Sample string: 1+2=3 
  1. <?php 
  2.  
  3. // create a string 
  4. $string = '1+2=3'; 
  5. // try to match our pattern 
  6.  
  7. if(preg_match("/^1\+2/i", $string)) { 
  8.  
  9. // if the pattern matches we echo this 
  10. echo 'The string begins with 1+2'; 
  11. } else { 
  12.  
  13. // if no match is found we echo this line 
  14.  
  15. echo 'No match found'; 
  16. }
  17.  ?>
From the code above you will see the script that display: "The string begins with 1+2" because if found the pattern 1+2 and escape the special meaning of + symbol in Meta characters. I you would not escape the the character preg_match("/^1+1/i/", $string); then it will display "No match found".

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