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String and String Functions

In PHP, a string is a sequence of characters enclosed within single quotes (‘ ‘) or double quotes (” “).

  • Strings can include any characters, including letters, numbers, and special characters.
  • PHP provides various functions to manipulate, search, and format strings.

Note: You can use double or single quotes, but you should be aware of the differences between the two.

  • Double quoted strings perform action on special characters.
$x = "John";
echo "Hello $x";

//output
// Hello John
  • Single quoted strings does not perform such actions, it returns the string like it was written, with the variable name:
$x = "John";
echo 'Hello $x';

//output
// Hello $x

PHP provides a variety of built-in string functions to manipulate and process strings.Here are some of the most commonly used string functions:

1.) strlen()

  • Returns the length of a string (i.e., the number of characters).
$str = "Hello, World!";
echo strlen($str);  // Output: 13

2.) str_word_count()

  • Counts the number of words in a string.
$str = "Hello World!";
echo str_word_count($str);  // Output: 

3.) str_replace()

  • Replaces all occurrences of a search string with a replacement string.
$str = "Hello, World!";
echo str_replace("World", "PHP", $str);  // Output: Hello, PHP!

4.) strtoupper()

  • Converts all characters of a string to uppercase.
$str = "hello";
echo strtoupper($str);  // Output: HELLO

5.) strtolower()

  • Converts all characters of a string to lowercase.
$str = "HELLO";
echo strtolower($str);  // Output: hello

6.) strcmp()

  • Compares two strings. It returns 0 if the strings are equal, a negative number if the first string is less than the second, and a positive number if the first string is greater.
$str1 = "apple";
$str2 = "banana";
echo strcmp($str1, $str2);  // Output: Negative value (because "apple" is less than "banana")
  • Data Manipulation: String functions allow you to manipulate user inputs or data from external sources (like databases) in PHP.
  • Search and Match: Functions like strpos() and str_replace() help you search for specific patterns, substrings, or replace content in strings.
  • Formatting: Functions such as ucwords(), strtoupper(), and strtolower() help format text, making it more presentable.
  • Text Processing: Functions like substr() and trim() allow for efficient text processing, such as extracting a part of a string or removing unwanted characters.

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