`urlencode` vs. `rawurlencode`: When Should I Use Which URL Encoding?

Decoding the Differences Between urlencode and rawurlencode

When constructing URLs with dynamic variables, developers have two encoding options: urlencode and rawurlencode. Understanding their distinct characteristics is essential for optimal URL creation.

urlencode vs rawurlencode

The primary difference lies in how spaces are handled. urlencode renders spaces as " " signs, while rawurlencode converts them to " " hexadecimal values. This distinction arises from different standards: urlencode adheres to the form-encoding conventions used in traditional web forms, whereas rawurlencode follows modern RFC standards (RFC 3986).

When to Use Each Encoding

Interoperability with external systems is a crucial factor in choosing the appropriate encoding. If compatibility with non-PHP platforms is paramount, rawurlencode is favored due to its adherence to widely accepted RFC standards.

However, if dealing with legacy systems that expect form-encoded URLs, urlencode remains the preferred option. This applies especially to scenarios where spaces need to be represented as " " signs instead of " ".

Technical Details

rawurlencode follows RFC 3986, encoding non-alphanumeric characters as "%HEX" sequences, adhering to specific character escaping rules. It accurately protects special characters from being misinterpreted as URL delimiters.

urlencode aligns with application/x-www-form-urlencoded media type, encoding spaces as " " signs according to RFC 1866. This historical departure from the RFC 3986 encoding is a concession to legacy systems.

Additional Considerations

RFC 2396 defines valid URI syntax, emphasizing that the " " symbol is reserved in query components. Consequently, encoding spaces as " " signs (per urlencode) may lead to compatibility issues with strict URI standards.

For further clarification, refer to the comprehensive discussion at https://bytes.com/groups/php/5624-urlencode-vs-rawurlencode.

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