| Introduction to Web Development |
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| Basic PHP Syntax |
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| PHP Basics |
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| Variables and Data Types |
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| Functions in PHP |
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| User-defined Functions |
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| Built-in Functions |
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| Variable Scope |
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| Include and Require |
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| Working with Forms |
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| Forms in HTML |
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| Form Handling in PHP |
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| Working with Files |
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| File Handling |
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| File System Functions |
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| Working with Databases |
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| Introduction to Databases |
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| Advanced PHP Techniques |
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| Object-Oriented Programming (OOP) |
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| Error and Exception Handling |
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PHP offers a variety of built-in functions specifically designed to handle strings. Here’s a deeper look at some of the most commonly used string functions in PHP:
1. strlen()
Description: Returns the length of a given string.
$string = "Hello, world!";
echo strlen($string); // Outputs: 13
2. strpos()
Description: Finds the position of the first occurrence of a substring in a string.
$myString = "Hello, world!";
$position = strpos($myString, "world");
echo $position; // Outputs: 7
Note: Returns false if the substring is not found.
3. str_replace()
Description: Replaces all occurrences of the search string with the replacement string.
$originalString = "Hello, world!";
$newString = str_replace("world", "PHP", $originalString);
echo $newString; // Outputs: Hello, PHP!
4. substr()
Description: Returns a part of a string.
$string = "Hello, world!";
$substring = substr($string, 7, 5);
echo $substring; // Outputs: world
5. strtolower()
Description: Converts all characters in a string to lowercase.
$string = "HELLO, WORLD!";
$lowercaseString = strtolower($string);
echo $lowercaseString; // Outputs: hello, world!
6. strtoupper()
Description: Converts all characters in a string to uppercase.
$string = "hello, world!";
$uppercaseString = strtoupper($string);
echo $uppercaseString; // Outputs: HELLO, WORLD!
7. ucfirst()
Description: Capitalizes the first character of a string.
$string = "hello, world!";
$capitalizedString = ucfirst($string);
echo $capitalizedString; // Outputs: Hello, world!
8. ucwords()
Description: Capitalizes the first character of each word in a string.
$string = "hello, world!";
$capitalizedWords = ucwords($string);
echo $capitalizedWords; // Outputs: Hello, World!
9. trim()
Description: Strips whitespace (or other characters) from the beginning and end of a string.
$string = " Hello, world! ";
$trimmedString = trim($string);
echo $trimmedString; // Outputs: Hello, world!
10. ltrim()
Description: Strips whitespace (or other characters) from the beginning of a string.
$string = " Hello, world!";
$trimmedLeft = ltrim($string);
echo $trimmedLeft; // Outputs: Hello, world!
11. rtrim()
Description: Strips whitespace (or other characters) from the end of a string.
$string = "Hello, world! ";
$trimmedRight = rtrim($string);
echo $trimmedRight; // Outputs: Hello, world!
12. explode()
Description: Splits a string into an array by a specified delimiter.
$string = "Hello, world!";
$array = explode(", ", $string);
print_r($array); // Outputs: Array ( [0] => Hello [1] => world! )
13. implode()
Description: Joins array elements into a single string using a specified delimiter.
$array = ["Hello", "world!"];
$string = implode(", ", $array);
echo $string; // Outputs: Hello, world!
14. md5()
Description: Calculates the MD5 hash of a string.
$string = "Hello, world!";
$hash = md5($string);
echo $hash; // Outputs: 6cd3556deb0da54bca060b4c39479839
15. sha1()
Description: Calculates the SHA-1 hash of a string.
$string = "Hello, world!";
$hash = sha1($string);
echo $hash; // Outputs: d3486ae9136e7856bc42212385ea797094475802
16. htmlspecialchars()
Description: Converts special characters to HTML entities to prevent XSS attacks.
$string = "<a href='test'>Test</a>";
$safeString = htmlspecialchars($string);
echo $safeString; // Outputs: <a href='test'>Test</a>
17. htmlentities()
Description: Converts all applicable characters to HTML entities.
$string = "<a href='test'>Test</a>";
$safeString = htmlentities($string);
echo $safeString; // Outputs: <a href='test'>Test</a>
18. addslashes()
Description: Adds backslashes before certain characters in a string.
$string = "Hello, 'world'!";
$safeString = addslashes($string);
echo $safeString; // Outputs: Hello, \'world\'!
19. strstr()
Description: Finds the first occurrence of a string and returns the rest of the string.
$email = "user@example.com";
$domain = strstr($email, '@');
echo $domain; // Outputs: @example.com
20. strrev()
Description: Reverses a string.
$string = "Hello, world!";
$reversedString = strrev($string);
echo $reversedString; // Outputs: !dlrow ,olleH
21. sprintf()
Description: Returns a formatted string.
$number = 5;
$location = "tree";
$formattedString = sprintf("There are %d monkeys in the %s", $number, $location);
echo $formattedString; // Outputs: There are 5 monkeys in the tree
22. number_format()
Description: Formats a number with grouped thousands.
$number = 1234.56;
$formattedNumber = number_format($number, 2, '.', ',');
echo $formattedNumber; // Outputs: 1,234.56
23. str_pad()
Description: Pads a string to a new length.
$input = "Alien";
$padded = str_pad($input, 10, "*");
echo $padded; // Outputs: Alien*****
24. str_repeat()
Description: Repeats a string a specified number of times.
$input = "Hello";
$repeated = str_repeat($input, 3);
echo $repeated; // Outputs: HelloHelloHello
25. str_word_count()
Description: Counts the number of words in a string.
$string = "Hello, world!";
$wordCount = str_word_count($string);
echo $wordCount; // Outputs: 2
These functions are powerful tools for string manipulation and are essential for any PHP developer to master.
