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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 c ) 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 substr(0, sv.size()) == sv 2) the prefix is a single character. Effectively returns !empty() && Traits::eq(front(), c) 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 c - 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: __cpp_lib_starts_ends_with Example // Run this code #include <iostream> #include <string_view> auto main() -> int { using namespace std::literals; std::cout << std::boolalpha // bool starts_with(basic_string_view x) const noexcept; << "https://cppreference.com"sv.starts_with("http"sv) << ' ' // true << "https://cppreference.com"sv.starts_with("ftp"sv) << ' ' // false // bool starts_with(CharT x) const noexcept; << "C++20"sv.starts_with('C') << ' ' // true << "C++20"sv.starts_with('J') << ' ' // false // bool starts_with(const CharT* x) const; << std::string_view("string_view").starts_with("string") << ' ' // true << std::string_view("string_view").starts_with("String") << ' ' // false << '\n'; } Output: true false true false true 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 (C++17) (public member function) http://cppreference.com 2022.07.31 std::basic_...:starts_with(3)
NAME | Synopsis | Parameters | Return value | Notes | Example | Output: | See also
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