std::basic_string<CharT,Traits,Allocator>::starts_with - cppreference.com (original) (raw)

constexpr bool starts_with( std::basic_string_view<CharT,Traits> 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 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.

[edit] 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

[edit] Return value

true if the string begins with the provided prefix, false otherwise.

[edit] 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()

[edit] Example

#include #include #include   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) ); }

[edit] See also

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