[#boost-urls-decode-03]
= xref:boost.adoc[boost]::xref:boost/urls.adoc[urls]::decode
:relfileprefix: ../../
:mrdocs:

Apply percent‐decoding to an arbitrary string

== Synopsis

Declared in `<https://www.github.com/boostorg/url/blob/develop/include/boost/url/decode.hpp#Lundefined[boost/url/decode.hpp]>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
system::result<std::size_t>
decode(
    char* dest,
    std::size_t size,
    core::string_view s,
    xref:boost/urls/encoding_opts.adoc[encoding_opts] opt = {}) noexcept;
----

== Description

This function percent‐decodes the specified string into the destination buffer provided by the caller. The input is validated first; malformed escapes cause the returned result to hold an error instead of a size. If the buffer is too small, the output is truncated and the number of bytes actually written is returned.

== Example

[,cpp]
----
char buf[100];
auto n = decode( buf, sizeof(buf), "Program%20Files" );
assert( n && *n == 13 );
----
== Exception Safety

Throws nothing. Validation errors are reported in the returned result.

== Specification

* https://datatracker.ietf.org/dodc/html/rfc3986#section-2.1[2.1. Percent‐Encoding (rfc3986)]

== Return Value

The number of characters written to the destination buffer, or an error.

== Parameters

[cols="1,4"]
|===
|Name|Description

| *dest*
| The destination buffer to write to.
| *size*
| The number of writable characters pointed to by `dest`. If this is less than the decoded size, the result is truncated.
| *s*
| The string to decode.
| *opt*
| The decoding options. If omitted, the default options are used.
|===

== See Also

xref:boost/urls/decoded_size.adoc[`decoded_size`], xref:boost/urls/encoding_opts.adoc[`encoding_opts`], xref:boost/urls/make_pct_string_view.adoc[`make_pct_string_view`].


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