PHP strlen() And mb_strlen(): Get String Length

In PHP, strlen() and mb_strlen() functions are used to get the length of a string. However, they handle multi-byte characters differently.

1. strlen():

The strlen() function returns the number of bytes in a string.

Here's an example of how to use it:

$str = "Hello, World!";
echo strlen($str); // Outputs: 13

In the above example, strlen() counts each character as one byte, so it returns 13.

However, strlen() doesn't work correctly with multi-byte characters, like those found in UTF-8 encoded strings. For example:

$str = "こんにちは";
echo strlen($str); // Outputs: 15

In the above example, strlen() returns 15 because it's counting bytes, not characters. Each of these Japanese characters is a multi-byte character in UTF-8.

2. mb_strlen():

The mb_strlen() function returns the number of characters in a string, and it's multi-byte safe.

Here's an example of how to use it:

$str = "Hello, World!";
echo mb_strlen($str); // Outputs: 13

In the above example, mb_strlen() also counts each character as one, so it returns 13.

However, unlike strlen(), mb_strlen() also works correctly with multi-byte characters:

$str = "こんにちは";
echo mb_strlen($str); // Outputs: 5

In the above example, mb_strlen() correctly returns 5, because there are five characters in the string.

So, if you're working with multi-byte character encodings like UTF-8, it's safer to use mb_strlen() to get the length of a string. If you're certain your strings will only contain single-byte characters, you can use strlen().

Get string length in PHP with strlen():

The strlen() function is used to determine the length of a string in PHP.

// File: string_length_strlen.php
$string = "Hello, World!";
$length = strlen($string);

echo "String: $string\nLength: $length";
// Output: String: Hello, World!
//         Length: 13

Multibyte string length in PHP with mb_strlen():

For multibyte character encodings like UTF-8, use mb_strlen() to accurately get the length.

// File: multibyte_string_length_mb_strlen.php
$string = "��ã����磡";
$length = mb_strlen($string, 'UTF-8');

echo "String: $string\nLength: $length";
// Output: String: ��ã����磡
//         Length: 6

PHP strlen() vs mb_strlen() differences:

strlen() counts bytes, while mb_strlen() counts characters, making it suitable for multibyte encodings.

// File: strlen_vs_mb_strlen.php
$string = "��ã����磡";
$lengthStrlen = strlen($string);
$lengthMbStrlen = mb_strlen($string, 'UTF-8');

echo "String: $string\nLength (strlen): $lengthStrlen\nLength (mb_strlen): $lengthMbStrlen";
// Output: String: ��ã����磡
//         Length (strlen): 18
//         Length (mb_strlen): 6

Handling UTF-8 characters with mb_strlen() in PHP:

Use mb_strlen() with the appropriate character encoding to handle UTF-8 characters correctly.

// File: utf8_handling_mb_strlen.php
$string = "����ˤ��ϡ����磡";
$length = mb_strlen($string, 'UTF-8');

echo "String: $string\nLength: $length";
// Output: String: ����ˤ��ϡ����磡
//         Length: 10

Example code for strlen() and mb_strlen() in PHP:

Compare the results of strlen() and mb_strlen() for strings with multibyte characters.

// File: example_strlen_mb_strlen.php
$string = "Caf��";
$lengthStrlen = strlen($string);
$lengthMbStrlen = mb_strlen($string, 'UTF-8');

echo "String: $string\nLength (strlen): $lengthStrlen\nLength (mb_strlen): $lengthMbStrlen";
// Output: String: Caf��
//         Length (strlen): 5
//         Length (mb_strlen): 4

Case-insensitive string length with mb_strlen() in PHP:

mb_strlen() can be used with the mb_strtolower() function for case-insensitive length.

// File: case_insensitive_length_mb_strlen.php
$string = "Caf��";
$lowercaseString = mb_strtolower($string, 'UTF-8');
$length = mb_strlen($lowercaseString);

echo "String: $string\nLowercase: $lowercaseString\nLength: $length";
// Output: String: Caf��
//         Lowercase: caf��
//         Length: 4

Detecting character encoding before using mb_strlen() in PHP:

Detect the character encoding before using mb_strlen() to ensure accurate results.

// File: detect_encoding_before_mb_strlen.php
$string = "��ã����磡";
$encoding = mb_detect_encoding($string, 'UTF-8, ISO-8859-1', true);
$length = mb_strlen($string, $encoding);

echo "String: $string\nEncoding: $encoding\nLength: $length";
// Output: String: ��ã����磡
//         Encoding: UTF-8
//         Length: 6