REPLACE Function

Searches for the first string, and replaces it with the second. This differs from the REPLACE() function used outside of the regex object.

Category:	Regular Expression
Returned data type:	String

Syntax

Required Arguments

Details

Example

Syntax

r.REPLACE(input-string, replacement–value)

Required Arguments

input-string

specifies a string value in which you want to search for and replaced in the pattern defined by your compiled regular expression. This can be an explicit string ("MyValue"). This can also be a variable already defined in your expression code or passed to your expression node as a column from a previous node (MyValue or "My Value").

Requirement

input-string must not be NULL or blank.

replacement–value

specifies a string to replace input-string that was matched by the compiled regular expression.

Details

The REPLACE function extends the capabilities of the regex object from simply finding patterns that match a regular expression to replacing the matching substring with a new value. For example, if you wanted to match all substrings that match a pattern of two hyphens with any letter in between (-A-, -B-) and replace with a single letter (Z), you would compile your regular expression for finding the hyphen/letter/hyphen pattern. Then you would use "Z" as the replacement value of the REPLACE() function passing in a variable or string value for input.

The return value is a string value with the replacement made if a replacement could indeed be made given the regular expression in play and the value supplied for input. If no replacement could be made, then the original value for input is returned

There are limitations to this functionality. You cannot easily replace the matched substring with a "captured" part of that substring. In the earlier example, you would have to parse the matched substring after it was found using FINDFIRST( ) or FINDNEXT( ) and create the replacement value based on that operation. But matched patterns can be of variable length, so guessing the position of parts of substrings can be tricky.

Compare this to similar functionality provided with using regular expressions as part of standardization definitions. In the case of QKB definitions that use regular expressions, much smarter replacements can be made because the regular expression engine enables you to use captured substrings in replacement values.

Example

Note: This example can be run in a stand-alone expression node if the Generate rows when no parent is specified option is selected. If passing data to this node, turn this setting off and remove the SETEOF() function. Unless stated otherwise, all code shown should be entered in the Expression tab of the Expression node.

//Define two string variables
string MyString
string MyNewString
 
// Provide a value for MyString
MyString = "12Flux"
 
// Defined a regular expression object variable
regex r
// Compile a regular expression that will look for a series of digits
// either 2 or 3 digits long
r. compile("\d{2,3}")
// Use the replace function to place "Data" in place of the found
// pattern and save that in a new string variable.
// If you change MyString to 1234 or 12345 you can see the
// difference in how the pattern is found
MyNewString = r.replace(MyString,"Data")
// Terminate the expression node processing
seteof()