Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. — Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

This is the documentation for a snapshot of the develop branch, built from commit adcd4c09f0.

Returns the value for a field, or throws an exception.

string_view const
at(
    field name) const;

If more than one field with the specified name exists, the first field defined by insertion order is returned.

Name	Description
`name`	The name of the field.

The field value.

Type	Thrown On
`std::out_of_range`	if the field is not found.