std::basic_string_view<CharT,Traits>::npos
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std::basic_string_view
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Constants
basic_string_view::npos
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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.
[edit] Example
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#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")); }
[edit] See also
constexpr size_type
npos [static]
the special value size_type(-1), its exact meaning depends on the context[edit]