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std::basic_string_view::npos(3) C++ Standard Libary std::basic_string_view::npos(3)


std::basic_string_view::npos - std::basic_string_view::npos


static constexpr size_type npos = size_type(-1); (since C++17)

This is a special value equal to the maximum value representable by the type
size_type. The exact meaning depends on context, but it is generally used either as
end of view indicator by the functions that expect a view index or as the error
indicator by the functions that return a view index.


// Run this code

#include <string_view>

constexpr bool
contains(std::string_view const what, std::string_view const where) noexcept
return std::string_view::npos != where.find(what);

int main()
using namespace std::literals;

static_assert(contains("water", "in a bottle of water"));
static_assert(!contains("wine", "in a bottle of champagne"));
static_assert(""sv.npos == "haystack"sv.find("needle"));

See also

npos special value. The exact meaning depends on the context
[static] (public static member constant of