String Manipulation Functions

PHP provides numerous built-in functions for manipulating strings. Here are some common ones:

1. strpos(): Find the position of the first occurrence of a substring.

   <?php
   $haystack = "Hello, World!";
   $needle = "World";
   $position = strpos($haystack, $needle);
   echo $position;  // Outputs: 7
   ?>
   

2. substr(): Return a part of a string.

   <?php
   $string = "Hello, World!";
   $substring = substr($string, 7, 5);
   echo $substring;  // Outputs: World
   ?>
   

3. str_replace(): Replace all occurrences of a search string with a replacement string.

   <?php
   $string = "Hello, World!";
   $newString = str_replace("World", "PHP", $string);
   echo $newString;  // Outputs: Hello, PHP!
   ?>
   

4. trim(): Remove whitespace (or other characters) from the beginning and end of a string.

   <?php
   $string = "   Hello, World!   ";
   $trimmedString = trim($string);
   echo $trimmedString;  // Outputs: Hello, World!
   ?>
   

5. strtoupper(): Convert a string to uppercase.

   <?php
   $string = "Hello, World!";
   $upperString = strtoupper($string);
   echo $upperString;  // Outputs: HELLO, WORLD!
   ?>
   

6. strtolower(): Convert a string to lowercase.

   <?php
   $string = "Hello, World!";
   $lowerString = strtolower($string);
   echo $lowerString;  // Outputs: hello, world!
   ?>
   

7. ucfirst(): Capitalize the first character of a string.

   <?php
   $string = "hello, world!";
   $capitalizedString = ucfirst($string);
   echo $capitalizedString;  // Outputs: Hello, world!
   ?>
   

8. strlen(): Get the length of a string.

   <?php
   $string = "Hello";
   echo strlen($string);  // Outputs: 5
   ?>
   

Multiline Strings

For multiline strings, you can use heredoc or nowdoc syntaxes.

1. Heredoc:

   • Allows for the creation of multi-line strings without escaping quotes.
   • Syntax: <<<EOT

   Example:

   <?php
   $string = <<<EOT
   This is a multiline
   string using heredoc.
   EOT;
   
   echo $string;
   ?>
   

2. Nowdoc:

   • Similar to heredoc but does not parse variables.
   • Syntax: <<<'EOT'

   Example:

   <?php
   $string = <<< 'EOT'
   This is a multiline
   string using nowdoc. Variables like $variable
   will not be parsed.
   EOT;
   
   echo $string;
   ?>
   

String Conversion Functions

1. str_split(): Convert a string into an array of characters.

   <?php
   $string = "Hello";
   $array = str_split($string);
   print_r($array);  // Outputs: Array ( [0] => H [1] => e [2] => l [3] => l [4] => o )
   ?>
   

2. explode(): Split a string by a specified delimiter.

   <?php
   $string = "apple,banana,orange";
   $array = explode(",", $string);
   print_r($array);  // Outputs: Array ( [0] => apple [1] => banana [2] => orange )
   ?>
   

3. implode(): Join array elements into a single string.

   <?php
   $array = array("apple", "banana", "orange");
   $string = implode(", ", $array);
   echo $string;  // Outputs: apple, banana, orange
   ?>
   

Summary

• Defining Strings: Strings are enclosed in single or double quotes.
• Concatenation: Combine strings using the . operator.
• Manipulation Functions: PHP provides a variety of functions for working with strings, including searching, replacing, and formatting.
• Multiline Strings: Use heredoc or nowdoc syntaxes for multi-line text.
• Conversion Functions: Convert strings to arrays and vice versa using functions like str_split(), explode(), and implode().