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

string::try_at

Return a character with bounds checking.

boost::system::result< char & >
try_at(
    std::size_t pos) noexcept;
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boost::system::result< char const & >
try_at(
    std::size_t pos) const noexcept;
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