Master PHP String Truncation: 5 Methods for Clean, Multilingual Output

In PHP development, cutting strings is a frequent task, and choosing the right function can improve performance and avoid garbled output.

1. substr(): ASCII and fixed‑byte strings

substr()

is a built‑in function suitable for single‑byte encodings such as ISO‑8859‑1. Its syntax is substr(string $string, int $start, ?int $length = null). Example:

$str = "Hello World";
echo substr($str, 0, 5); // Hello

Pros: fast execution because it is implemented in C.

Cons: does not support multibyte characters; misuse can cause garbled Chinese text.

2. mb_substr(): Multibyte‑safe truncation

For UTF‑8 and other multibyte encodings, use mb_substr(). Syntax:

mb_substr(string $str, int $start, ?int $length = null, ?string $encoding = null)

. Example:

$str = "你好世界Hello";
echo mb_substr($str, 0, 4, 'UTF-8'); // 你好世

Pros: correctly handles Chinese, Japanese and other multibyte characters.

Note: the mbstring extension must be enabled.

3. preg_match() with regular expressions

When you need to extract patterns (e.g., URLs, emails, quoted text), combine preg_match() with a regex. Example extracting text inside quotes:

$str = 'name="张三"';
preg_match('/"([^\"]+)"/', $str, $matches);
echo $matches[1]; // 张三

Pros: flexible for complex extraction rules.

Cons: slower than simple functions; regex errors can cause bugs.

4. explode() + array handling

If the string contains a known delimiter, split it with explode() and pick the needed part. Example obtaining a file extension:

$filename = "example.jpg";
$parts = explode('.', $filename);
$ext = end($parts); // jpg

Pros: clear logic for structured strings.

Note: if the delimiter is absent, the original string is returned as a single‑element array; further handling may be required.

5. Custom function for safe truncation with ellipsis

A reusable helper can truncate a string to a maximum length and append “...” when needed, while supporting multibyte encodings:

function truncateString($str, $maxLength, $encoding = 'UTF-8') {
    if (mb_strlen($str, $encoding) > $maxLength) {
        return mb_substr($str, 0, $maxLength, $encoding) . '...';
    }
    return $str;
}
echo truncateString("这是一段很长的中文描述", 8); // 这是一段很长...

This approach balances readability and multilingual support, making it suitable for front‑end display scenarios.

Choosing the appropriate method depends on the string’s language and format: use substr for pure English, mb_substr for Chinese or other multibyte text, explode when a delimiter exists, and regular expressions for complex patterns.