`urlencode()` vs. `rawurlencode()`: When Should I Use Each for URL Encoding?

urlencode vs rawurlencode: Understanding the Encoding Differences

When incorporating dynamic values into URLs, developers have the option of using either urlencode() or rawurlencode() to encode the string. While both functions are intended for URL encoding, they follow different specifications and have distinct outcomes.

rawurlencode conforms to RFC 1738 (prior to PHP 5.3.0) and RFC 3986 (afterwards). According to RFC 3986, all non-alphanumeric characters except -_.~ are replaced with a percent (%) sign followed by two hex digits. This encoding is designed to protect URLs from potential character conversions or misinterpretations as special URL delimiters.

In contrast, urlencode aligns with the encoding specified in RFC 1866 for application/x-www-form-urlencoded media types. It encodes non-alphanumeric characters excluding -_. with % signs and hex digits, while replacing spaces with plus ( ) signs. This encoding emulates how form data is posted over HTTP.

Which is Preferred?

Choosing between urlencode() and rawurlencode() depends on the specific context. For ensuring interoperability with various systems, rawurlencode() is generally recommended. It adheres to the global RFC standard, maximizing compatibility with different implementations.

However, there are legacy systems that expect form-encoded query strings with spaces represented as rather than . In such cases, urlencode() should be employed.

Note that encoding requirements can vary depending on the use case and target system. It's advisable to refer to the relevant RFC standards or consult with the system documentation for specific guidance.

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