JSTL fn:substringBefore() Function

Last Updated : 17 Dec, 2023

In JSTL, the fn:substringBefore() function is mainly used to return the subset of the string before a specific substring. This function extracts the substring before a specified delimiter in the given input string. In this article, we will discuss about the syntax, parameters, and example of the fn:substringBefore() function.

The fn:substringBefore() function is part of the JSTL core tag library.
The function simplifies the string manipulation in JSP applications.

Syntax of fn:substringBefore() function:

${fn:substringBefore(string, delimiter)}

${fn:substringBefore(..)}: This is the JSTL expression for extracting a subset of a string.
string: This is the input string parameter from which we need to extract the substring.
delimiter: This is the delimiter attribute that defines the end of the substring to be extracted.

Example of JSTL fn:substringBefore() Function

In this example, we will see how to find the length of a string using the JSTL fn:substringBefore() Function.

HTML

<%@ page contentType="text/html;charset=UTF-8" language="java" %> 
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> 
<%@ taglib uri="http://java.sun.com/jsp/jstl/functions" prefix="fn" %> 
<html> 
<head> 
    <title>JSTL fn:substringBefore() Example</title> 
</head> 
<body> 
<c:set var="inputString" value="GeeksforGeeks is Good"/> 
<p>Original String: ${inputString}</p> 
<p>Substring before "is": ${fn:substringBefore(inputString, 'is')}</p> 
</body> 
</html> 

Output:

Original String: GeeksforGeeks is Good
Substring before "is": GeeksforGeeks

Output Screen of the above Program:

Output of Example of JSTL fn:substringBefore() Function

Explanation of the above Program:

We have initialized the inputString variable with the string value “GeeksforGeeks is Good”.
Then, by using the fn:substringBefore() function, we extract the substring before the occurrence of the substring as “is“.
So before the substring, the output is GeeksforGeeks which we are printing on screen by using the <p> tag of HTML.

Suggest improvement

JSTL fn:substring() Function

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