? PHP String Search & Find Position Functions

? Quick Overview

PHP provides built-in functions to search for substrings within a string and determine their exact position. These functions are commonly used for validation, parsing, and conditional logic.

? Key Concepts

• strpos() – Finds the first occurrence of a substring
• strrpos() – Finds the last occurrence of a substring
• stripos() – Case-insensitive search (first occurrence)
• strripos() – Case-insensitive search (last occurrence)

? Syntax & Theory

• All position functions return an integer index (starting from 0)
• If the substring is not found, false is returned
• Always use strict comparison (!== false) when checking results

? Example 1: Using strpos()

// Find the first occurrence of a substring
<?php
$string = "Hello World";
$position = strpos($string, "World");
echo $position;
?>

? Example 2: Using strrpos()

// Find the last occurrence of a substring
<?php
$string = "Hello World World";
$position = strrpos($string, "World");
echo $position;
?>

? Interactive Logic Flow

// Demonstrates logical flow of substring checking
If string contains substring
Return position
Else
Return false

? Use Cases

• Checking if a keyword exists in user input
• Parsing URLs, emails, or filenames
• Form validation and content filtering
• Search and highlight features