PHP convert_uuencode() Function

What You’ll Learn

The convert_uuencode() function encodes strings with the uuencode algorithm—a legacy binary-to-text format from Unix and early email. It turns raw bytes into printable ASCII and pairs with convert_uudecode() for decoding.

Definition and Usage

In PHP, convert_uuencode() takes any string—text or binary—and returns a uuencoded representation made of printable ASCII characters. Each output line starts with a length character, followed by encoded payload. Data longer than 45 bytes is split across multiple lines automatically.

📝 Syntax

The convert_uuencode() function accepts one string parameter:

string convert_uuencode(string $string)

Parameters

• $string — the data to encode. Can be plain text, binary bytes, or a mix of both.

Return Value

Returns the uuencoded string. Since PHP 8.0, encoding an empty string returns "" (previously it incorrectly returned false). The original input is not modified.

Examples Gallery

Run these examples in PHP 7+. Each demonstrates a common pattern beginners encounter with convert_uuencode().

<?php
$data    = "Hello, PHP!";
$encoded = convert_uuencode($data);

echo "Original:  $data\n";
echo "UUEncoded: $encoded\n";
?>

Original:  Hello, PHP!
UUEncoded: +2&5L;&\L(%!(4"$`

<?php
$data    = "test\ntext text\r\n";
$encoded = convert_uuencode($data);

echo $encoded;
?>

0=&5S=`IT97AT('1E>'0-"@``

<?php
$binary  = "Binary\x00\xFFdata";
$encoded = convert_uuencode($binary);
$back    = convert_uudecode($encoded);

echo "Original (hex): " . bin2hex($binary) . "\n";
echo "Encoded:        $encoded\n";
echo "Round-trip OK:  " . ($back === $binary ? "yes" : "no") . "\n";
?>

Original (hex): 42696e61727900ff64617461
Encoded:        ,0FEN87)Y`/]D871A"
Round-trip OK:  yes

<?php
$data    = "The quick brown fox jumps over the lazy dog";
$encoded = convert_uuencode($data);

$origLen = strlen($data);
$encLen  = strlen($encoded);
$overhead = round(($encLen / $origLen - 1) * 100);

echo "Original: $origLen bytes\n";
echo "Encoded:  $encLen bytes\n";
echo "Overhead: ~{$overhead}%\n";
?>

Original: 43 bytes
Encoded:  61 bytes
Overhead: ~42%

<?php
$data = "Sample binary\xFF\xFE data";

$uu  = convert_uuencode($data);
$b64 = base64_encode($data);

echo "uuencode length:  " . strlen($uu) . "\n";
echo "Base64 length:    " . strlen($b64) . "\n";

echo "uudecode match:   " . (convert_uudecode($uu) === $data ? "yes\n" : "no\n");
echo "base64 match:     " . (base64_decode($b64) === $data ? "yes\n" : "no\n");
?>

uuencode length:  29
Base64 length:    28
uudecode match:   yes
base64 match:     yes

🚀 Common Use Cases

• Legacy email attachments — produce uuencoded sections compatible with old Unix mail systems.
• Maintaining old PHP scripts — understand and extend code that still calls uuencode functions.
• Binary-to-text transport — represent binary data as printable ASCII for text-only channels.
• Round-trip testing — verify encoded output decodes correctly with convert_uudecode().
• Learning encoding history — compare uuencode with modern Base64 approaches.

📝 Notes

• Output does not include begin or end wrapper lines found in standalone uuencode files.
• Encoded data is roughly 35–45% larger than the original, depending on input length.
• Data longer than 45 bytes is automatically split across multiple encoded lines.
• For new projects, prefer base64_encode() / base64_decode().
• uuencode and uudecode functions were deprecated in PHP 8.4; plan migrations for long-term PHP 9 compatibility.

💡 Best Practices