String Manipulation

String manipulation refers to the process of creating, modifying, analyzing, and transforming sequences of characters, commonly known as strings. In programming, strings are fundamental data types used to represent text, such as names, messages, file paths, URLs, and any other textual information. Effective string manipulation is crucial for a wide range of tasks, including:

* Data Processing: Extracting specific information from logs, parsing user input, or formatting data for display.
* User Interface (UI): Presenting text to users in a readable format, validating input fields, or customizing messages.
* Text Analysis: Searching for keywords, counting words, or performing sentiment analysis.
* File Handling and Networking: Constructing file paths, processing URLs, or formatting data for network transmission.

Common string manipulation operations include:

1. Concatenation: Combining two or more strings into a single string.
2. Length Calculation: Determining the number of characters in a string.
3. Substring Extraction: Retrieving a portion of a string based on its starting position and length.
4. Searching: Finding the position of a specific substring within a larger string.
5. Replacement: Substituting occurrences of one substring with another.
6. Case Conversion: Changing the case of characters (e.g., to uppercase, lowercase, title case).
7. Trimming: Removing leading and/or trailing whitespace or specified characters from a string.
8. Splitting: Breaking a string into an array of substrings based on a delimiter.
9. Joining: Combining elements of an array into a single string using a specified delimiter.
10. Comparison: Checking if two strings are identical or comparing them alphabetically.

PHP, being a language widely used for web development, offers a rich set of built-in functions specifically designed for robust and efficient string manipulation. These functions make it straightforward to perform complex text operations with minimal code.

Example Code

<?php

// 1. String Declaration
$greeting = "Hello";
$name = "World";
$phrase = "  PHP is a powerful scripting language for web development.  ";

echo "--- Basic String Operations ---\n";

// 2. Concatenation: Combining strings
$fullGreeting = $greeting . ", " . $name . "!";
echo "Concatenation: " . $fullGreeting . "\n"; // Output: Hello, World!

// 3. String Length: Determining the number of characters
$stringLength = strlen($fullGreeting);
echo "Length of '" . $fullGreeting . "': " . $stringLength . "\n"; // Output: 14

// 4. Substring Extraction: Getting a part of a string
$substring = substr($fullGreeting, 7, 5); // Start at index 7, take 5 characters
echo "Substring (from index 7, 5 chars): " . $substring . "\n"; // Output: World

$lastPart = substr($fullGreeting, -6); // Get last 6 characters
echo "Substring (last 6 chars): " . $lastPart . "\n"; // Output: World!

// 5. Searching for a Substring: Finding its position
$position = strpos($fullGreeting, "World");
if ($position !== false) {
    echo "Substring 'World' found at position: " . $position . "\n"; // Output: 7
} else {
    echo "Substring 'World' not found.\n";
}

$notfound = strpos($fullGreeting, "PHP");
if ($notfound === false) {
    echo "Substring 'PHP' not found (as expected).\n";
}

// 6. String Replacement: Swapping parts of a string
$newGreeting = str_replace("World", "PHP Developers", $fullGreeting);
echo "Replacement: " . $newGreeting . "\n"; // Output: Hello, PHP Developers!

echo "\n--- Case Conversion and Trimming ---\n";

// 7. Case Conversion
$lowerCase = strtolower($newGreeting);
echo "Lowercase: " . $lowerCase . "\n"; // Output: hello, php developers!

$upperCase = strtoupper($newGreeting);
echo "Uppercase: " . $upperCase . "\n"; // Output: HELLO, PHP DEVELOPERS!

$firstCharUpper = ucfirst($lowerCase); // Makes first char of string uppercase
echo "First char uppercase: " . $firstCharUpper . "\n"; // Output: Hello, php developers!

$wordsFirstCharUpper = ucwords($lowerCase); // Makes first char of each word uppercase
echo "Words first char uppercase: " . $wordsFirstCharUpper . "\n"; // Output: Hello, Php Developers!

// 8. Trimming: Removing whitespace from beginning and end
echo "Original phrase with leading/trailing spaces: '" . $phrase . "'\n";
$trimmedPhrase = trim($phrase);
echo "Trimmed phrase: '" . $trimmedPhrase . "'\n"; // Output: 'PHP is a powerful scripting language for web development.'

// You can also specify characters to trim
$charTrim = "///Hello World///";
echo "Original with specific chars to trim: '" . $charTrim . "'\n";
echo "Trimmed ('/'): '" . trim($charTrim, "/") . "'\n"; // Output: 'Hello World'

echo "\n--- Splitting and Joining Strings ---\n";

// 9. Splitting a string into an array
$sentence = "apple,banana,orange,grape";
$fruitsArray = explode(",", $sentence);
echo "Original sentence: " . $sentence . "\n";
echo "Split into an array (first element): " . $fruitsArray[0] . "\n"; // Output: apple
echo "Split into an array (all elements):\n";
print_r($fruitsArray);

// 10. Joining an array into a string
$newSentence = implode(" - ", $fruitsArray);
echo "Joined array with ' - ': " . $newSentence . "\n"; // Output: apple - banana - orange - grape

echo "\n--- Advanced String Functions (Example) ---\n";

// Checking if a string starts with a substring (PHP 8+ str_starts_with)
$url = "https://www.example.com/page";
if (str_starts_with($url, "https://")) {
    echo "'" . $url . "' starts with 'https://'\n";
}

// Checking if a string ends with a substring (PHP 8+ str_ends_with)
if (str_ends_with($url, ".com/page")) {
    echo "'" . $url . "' ends with '.com/page'\n";
}

// Using sprintf for formatted output
$item = "laptop";
$price = 1200.50;
$formattedString = sprintf("The %s costs $%.2f.", $item, $price);
echo $formattedString . "\n"; // Output: The laptop costs $1200.50.

?>

Example Code

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