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 an older version of Boost and was released in 2024. The current version is 1.90.0.

object::count

object::count

Count the number of elements with a specific key.

Synopsis

std::size_t
count(
    string_view key) const noexcept;

Description

This function returns the count of the number of elements match key. The only possible return values are 0 and 1.

Complexity

Constant on average, worst case linear in size().

Exception Safety

No-throw guarantee.

Parameters

Name	Description
`key`	The key of the element to find.