How To Get The Last 7 Characters Of A PHP String?

Syntax and Parameters of substr()

The basic structure of the substr() function is:

substr(string $string, int $start, int $length = ?): string

• $string: The input string you want to extract characters from.
• $start: The position where the extraction should begin. If negative, it counts from the end of the string.
• $length: Optional. The number of characters to extract. If omitted, it extracts to the end of the string.

To get the last 7 characters of a string, use a negative value for the $start parameter. Set it to -7 to start extracting from the 7th character from the end of the string. You can omit the $length parameter, as we want to extract all characters from that point to the end of the string.

This method works for any string length, making it useful for various string sizes.

$string = "Hello, World! This is a long string.";
$last_seven = substr($string, -7);
echo $last_seven; // Output: "string."

Code Example

Here's a code snippet that shows how to extract the last 7 characters from a string using the substr() function:

$dynamicstring = "2490slkj409slk5409els";
$newstring = substr($dynamicstring, -7);
echo "The new string is: " . $newstring;

This code will output:

The new string is: 5409els

Let's look at the code:

1. We have a variable $dynamicstring with our input string.
2. We use the substr() function to extract the last 7 characters:
   • The first argument is our input string $dynamicstring.
   • The second argument is -7, which tells PHP to start 7 characters from the end of the string.
3. We store the result in the $newstring variable.
4. We echo the result with a message.

This method works for strings of any length. If the string is shorter than 7 characters, it will return the whole string. For strings 7 characters or longer, it will always return the last 7 characters.

You can change the number -7 to extract a different number of characters from the end of the string. For example, using -5 would extract the last 5 characters.

$dynamicstring = "2490slkj409slk5409els";
$newstring = substr($dynamicstring, 0, 7);
echo "The new string is: " . $newstring;

The new string is: 2490slk

Using mb_substr() for Multibyte Strings

When working with strings that contain multibyte characters, like UTF-8 encoded text, the mb_substr() function is a better option than the regular substr(). This function is part of PHP's Multibyte String extension.

Use mb_substr() when:

• Your string has characters that use more than one byte, like emojis or non-Latin alphabets.
• You want to count characters accurately in multilingual applications.

The main differences from regular substr() are:

• mb_substr() treats multibyte characters as single units, while substr() might split them.
• You need to specify the character encoding as the fourth parameter (e.g., 'UTF-8').
• It's slower than substr() but gives more accurate results for multibyte strings.

Here's an example of using mb_substr():

$string = "こんにちは世界"; // "Hello World" in Japanese
$last_seven = mb_substr($string, -7, null, 'UTF-8');
echo $last_seven; // Output: "にちは世界"

mb_internal_encoding('UTF-8');
$string = "こんにちは世界";
$last_seven = mb_substr($string, -7);
echo $last_seven; // Output: "にちは世界"

Using str_split() and array_slice()

Another way to extract the last 7 characters involves breaking down the string into an array, slicing it, and then rejoining the elements. This method can be useful when you need to do more operations on the characters.

Here's how you can do it:

1. Use str_split() to break the string into an array of characters.
2. Use array_slice() to get the last 7 elements of the array.
3. Use implode() to join the array elements back into a string.

Here's an example:

$dynamicstring = "2490slkj409slk5409els";
$char_array = str_split($dynamicstring);
$last_seven_array = array_slice($char_array, -7);
$newstring = implode('', $last_seven_array);
echo "The new string is: " . $newstring;

This method works well for strings with single-byte characters. However, for multibyte strings, you should use mb_str_split() instead of str_split() to handle characters properly.

While this approach is more complex than using substr(), it can be useful when you need to do more array operations on the characters before rejoining them.