std::basic_...starts_with(3)

💖 NAME 💖

Okay bestie, welcome to std::basic_...starts_with(3) from the C++ Standard Libary (yes, that's the manual's spelling, not a typo I made 😭). The NAME entry is literally std::basic_string::starts_with — std::basic_string::starts_with. No cap, that's the whole thing. 💅

✨ Synopsis ✨

(1) (since C++20)
constexpr bool starts_with( std::basic_string_view<CharT,Traits> sv ) const noexcept;

(2) (since C++20)
constexpr bool starts_with( CharT ch ) const noexcept;

(3) (since C++20)
constexpr bool starts_with( const CharT* s ) const;

This checks if the string begins with the given prefix. The prefix may be one of the following:

1. A string view sv (which may be a result of implicit conversion from another std::basic_string).
2. A single character ch.
3. A null-terminated character string s.

All three overloads effectively return std::basic_string_view<CharT, Traits>(data(), size()).starts_with(x), where x is the parameter.

🌸 Parameters 🌸

• sv — a string view which may be a result of implicit conversion from another std::basic_string
• ch — a single character
• s — a null-terminated character string

🦋 Return value 🦋

true if the string begins with the provided prefix, false otherwise. That's it, bestie — binary slay. 💖

🎀 Notes 🎀

Feature-test macro vibes:

• Feature-test macro — __cpp_lib_starts_ends_with
• Value — 201711L
• Std — (C++20)
• Feature — String prefix and suffix checking: starts_with() and ends_with()

✨ Example ✨

Run this code, bestie 👇

        #include <cassert>
        #include <string>
        #include <string_view>

        int main()
        {
            using namespace std::literals;

            const auto str = "Hello, C++20!"s;

            assert
            (""
                && str.starts_with("He"sv)  // (1)
                && !str.starts_with("he"sv) // (1)
                && str.starts_with("He"s)   // (1) implicit conversion string
       to string_view
                && !str.starts_with("he"s)  // (1) implicit conversion string
       to string_view
                && str.starts_with('H')     // (2)
                && !str.starts_with('h')    // (2)
                && str.starts_with("He")    // (3)
                && !str.starts_with("he")   // (3)
            );
        }

👑 See also 👑

• ends_with — checks if the string ends with the given suffix (C++20) (public member function)
• starts_with — checks if the string view starts with the given prefix (C++20) (public member function of std::basic_string_view<CharT,Traits>)
• ends_with — checks if the string view ends with the given suffix (C++20) (public member function of std::basic_string_view<CharT,Traits>)
• contains — checks if the string contains the given substring or character (C++23) (public member function)
• contains — checks if the string view contains the given substring or character (C++23) (public member function of std::basic_string_view<CharT,Traits>)
• compare — compares two strings (public member function)
• substr — returns a substring (public member function)

Source: http://cppreference.com · Version/date: 2024.06.10 · Page: std::basic_...starts_with(3) — mwah 💋✨