For JSTL-based applications, fn:indexOf() function is used to get the first occurrence index or the position of the substring in the main string. This function-
- returns the position of the substring if it is found in the main string.
- If it is not found, then it returns the -1 value and prints on the screen.
In this article, we will see the syntax of this function its parameters, and the example with the output and explanation.
Syntax of fn:indexOf() Function
${fn:indexOf(string, substring)}
where,
- string: This is the input or specified sting in which we are searching for the substring.
- substring: This is the string to be located within the input string. If it is found the index is been returned or else the -1 is been returned.
Example of JSTL fn:indexOf() Function
Below is the implementation of JSTL fn:indexOf() Function:
HTML
<%@ page contentType="text/html;charset=UTF-8" language="java" %> <%@ taglib uri="http://java.sun.com/jsp/jstl/functions" prefix="fn" %> <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %> <html>
<head>
<title>JSTL fn:indexOf() Example</title>
</head>
<body>
<c:set var="inputString" value="Welcome to GeeksforGeeks"/>
<c:set var="substringToFind" value="Geeks"/>
<h3>Original String: ${inputString}</h3>
<h3>Substring to Find: ${substringToFind}</h3>
<c:set var="indexOfSubstring" value="${fn:indexOf(inputString, substringToFind)}"/>
<h3>Index of Substring: ${indexOfSubstring}</h3>
</body>
</html>
|
Output:
Original String: Welcome to GeeksforGeeks
Substring to Find: Geeks
Index of Substring: 11
Output Screen of JSTL fn:indexOf() Function:
Explanation of the above Program:
- we have stored the “Welcome to GeeksforGeeks” value in the inputString variable.
- Then we are using the fn:indexOf() function to find the first occurrence of the given substring (Geeks) within the inputString.
- We can see that the first occurent of Geeks substring is at position 11. So the function has returned this value and we printed that value using the HTML tag <p>.
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