[#detail-FromHex]
= xref:detail.adoc[detail]::FromHex
:relfileprefix: ../
:mrdocs:

Writes the hex string (in reverse byte order) into a new uintN_t object and only returns a value iff all of the checks pass: ‐ Input length is uintN_t::size()*2 ‐ All characters are hex

== Synopsis

Declared in `<uint256.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class uintN_t>
std::optional<uintN_t>
FromHex(std::string_view str);
----

== Return Value

The parsed value, or std::nullopt if the length or characters are invalid.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *str*
| The hex string to parse, expected to be uintN_t::size()*2 characters.
|===


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