std::basic_string_view<CharT,Traits>::starts_with - cppreference.com (original) (raw)
| 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
the prefix is a string view. Effectively returns basic_string_view(data(), std::min(size(), sv.size())) == sv.
the prefix is a single character. Effectively returns !empty() && Traits::eq(front(), ch).
the prefix is a null-terminated character string. Effectively returns starts_with(basic_string_view(s)).
[edit] 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 |
[edit] Return value
true if the string view 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 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 ); }
[edit] See also
| ends_with(C++20) | checks if the string view ends with the given suffix (public member function) [edit] |
|---|---|
| starts_with(C++20) | checks if the string starts with the given prefix (public member function of std::basic_string<CharT,Traits,Allocator>) [edit] |
| ends_with(C++20) | checks if the string ends with the given suffix (public member function of std::basic_string<CharT,Traits,Allocator>) [edit] |
| contains(C++23) | checks if the string contains the given substring or character (public member function of std::basic_string<CharT,Traits,Allocator>) [edit] |
| contains(C++23) | checks if the string view contains the given substring or character (public member function) [edit] |
| compare | compares two views (public member function) [edit] |