====== Substitute String (Expression Function) ======

===== Purpose =====
The **Substitute String** function (SUBSTITUTE_STRING) is used to substitute one value for another in a string of text. Most often used to clean up strings of text that may contain invalid characters. 

{{::substitue_string_initial.png?direct&600|}}
===== Parameters =====
The **Substitute String** function has five parameters, two of which are required:

==== String to Search ====

Allowed Inputs: [[Field|field]] value or text string

The first required parameter is the string that is being searched. Either use the use the [[Query Builder]] to choose a field that contains the search value or use type a value to search for a text string. 

==== String to Find ====

Allowed Inputs: [[Field|field]] value or text string

The second required parameter of the **Substitute** function is the string that we are looking for.  It can either be obtained from a field using the Query Builder or from a literal string.

==== Replacement Value ====

Allowed Inputs: [[Field|field]] value or a text string

The third parameter, which is optional, it is a value that will replace the value that was found. If this option is blank or set to any empty string,"", then the values that are found will be removed from the string.

==== Instance ====

Allowed Inputs: [[Field|field]] value, a positive number, or 0 to ignore this parameter.

The fourth parameter, which is optional, is a number denoting which occurrence of the search value to replace. If this option is not used then the all occurrences are replaced.

==== Case Sensitive ====
//New as of Platform Version 15.11.1195//

Allowed Inputs: [[Field|field]] value, Yes or No.

The fifth parameter, which is optional, tells the function specifically whether to be case sensitive or not.  The default is 'Yes', case sensitive.

===== Output =====

The output of the **Substitute** function is a string with the value in the string to find parameter removed or replaced with the replacement value.

===== Example =====

A common use for this function is to replace or remove unwanted or invalid values from a string.  For example SUBSTITUTE_STRING("51%","%"," percent") would result in "51 percent".