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std::basic_...:starts_with(3) C++ Standard Libarystd::basic_...:starts_with(3) NAME std::basic_string_view::starts_with - std::ba- sic_string_view::starts_with Synopsis constexpr bool starts_with( basic_string_view sv ) const noexcept; (1) (since C++20) constexpr bool starts_with( CharT ch ) const noexcept; (2) (since C++20) constexpr bool starts_with( const CharT* s ) const; (3) (since C++20) Checks if the string view begins with the given prefix, where 1) the prefix is a string view. Effectively returns ba- sic_string_view(data(), std::min(size(), sv.size())) == sv. 2) the prefix is a single character. Effectively returns !empty() && Traits::eq(front(), ch). 3) the prefix is a null-terminated character string. Effectively re- turns starts_with(basic_string_view(s)). Parameters sv - a string view which may be a result of implicit conversion from std::basic_string ch - a single character s - a null-terminated character string Return value true if the string view begins with the provided prefix, false oth- erwise. Notes Feature-test macro Value Std Feature __cpp_lib_starts_ends_with 201711L (C++20) String prefix and suffix checking: starts_with() and ends_with() Example // Run this code #include <cassert> #include <string_view> int main() { using namespace std::literals; assert ("" // (1) starts_with( basic_string_view ) && "https://cppreference.com"sv.starts_with("http"sv) == true && "https://cppreference.com"sv.starts_with("ftp"sv) == false // (2) starts_with( CharT ) && "C++20"sv.starts_with('C') == true && "C++20"sv.starts_with('J') == false // (3) starts_with( const CharT* ) && std::string_view("string_view").starts_with("string") == true && std::string_view("string_view").starts_with("String") == false ); } See also ends_with checks if the string view ends with the given suffix (C++20) (public member function) starts_with checks if the string starts with the given prefix (C++20) (public member function of std::ba- sic_string<CharT,Traits,Allocator>) ends_with checks if the string ends with the given suffix (C++20) (public member function of std::ba- sic_string<CharT,Traits,Allocator>) contains checks if the string contains the given substring or character (C++23) (public member function of std::ba- sic_string<CharT,Traits,Allocator>) contains checks if the string view contains the given substring or character (C++23) (public member function) compare compares two views (public member function) http://cppreference.com 2024.06.10 std::basic_...:starts_with(3)
NAME | Synopsis | Parameters | Return value | Notes | Example | See also
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