matchRegex

matchRegex* ( pattern : string , aString : string ) : boolean
matchRegex ( pattern : string , aString : string , start : integer {, *} ) : boolean
matchRegex ( pattern : string , aString : string , start : integer , pos_found : integer , length_found : integer {, *} ) : boolean

Parameter	Type		Description
pattern	string	→	Regular expression (complete equality when using two parameters only)
aString	string	→	String in which search will be done
start	integer	→	Position in aString where search will start
pos_found	integer	←	Position of occurrence
length_found	integer	←	Length of occurrence
*		→	If passed: only searches at position indicated
Result	boolean	←	True = search has found an occurrence; Otherwise, False

Description

The matchRegex command searches for the regular expression pattern in aString. It checks the conformity of a character string with respect to a set of synthesized rules by means of a meta-language called "regular expression" or "rational expression". The regex abbreviation is commonly used to indicate these types of notations.

Pass the regular expression to search for in pattern. This consists of a set of characters used for describing a character string, using special characters.

Pass the string where you want to search for the regular expression in aString.

In start, pass the position at which to start the search in aString.

In pos_found and length_found variables, the command returns the position and length of the first occurrence found.

The optional * parameter indicates, when it is passed, that the search must be carried out at the position specified by start without searching any further in the case of failure.

The command returns true if the search has found an occurrence.

For more information about regex, refer to the dedicated Wikipedia page.

For more information about the syntax of the regular expression passed in the pattern parameter, refer to this page.

Example 1

Search in text by position. You want to find all tags in a text:

 declare (myText : string) -> result : collection
 var start : integer
 var vfound : boolean
 start = 1
 result = newCollection
 repeat
    vfound = matchRegex("<.*>",myText,start,pos_found,length_found)
    if(vfound)
       result.push(substring(myText,pos_found,length_found))
       start = pos_found+length_found
    end
 until(not(vfound))

Example 2

Search limiting the comparison of the pattern to the position indicated: Add a star to the end of one of the two previous syntaxes.

 var pos_found, length_found : integer
 var vfound : string

 vfound = matchRegex("a.b","---a-b---",1,pos_found,length_found)
  // returns true
 vfound = matchRegex("a.b","---a-b---",1,pos_found,length_found,*)
  // returns false
 vfound = matchRegex("a.b","---a-b---",4,pos_found,length_found,*)
  // returns true

Error management

In the event of an error, the command generates an error that you can intercept via a method installed by the onErrCall command.