std::basic_string_view<CharT,Traits>::npos

From cppreference.com
C++
Strings library
std::basic_string_view
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

Example

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

constexpr size_type npos [static] the special value size_type(-1)
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