std::basic_string_view<CharT,Traits>::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.
Example
#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
constexprsize_type npos [static] | the special value size_type(-1), its exact meaning depends on the context |
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