std::basic_string_view<CharT,Traits>::starts_with
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 returns
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
otherwise.
Notes
Feature testing macro: __cpp_lib_starts_ends_with
.
Example
#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
(C++20)
|
checks if the string view ends with the given suffix (public member function) |
(C++20)
|
checks if the string starts with the given prefix (public member function of std::basic_string<CharT,Traits,Allocator> ) |
(C++20)
|
checks if the string ends with the given suffix (public member function of std::basic_string<CharT,Traits,Allocator> ) |
(C++23)
|
checks if the string contains the given substring or character (public member function of std::basic_string<CharT,Traits,Allocator> ) |
(C++23)
|
checks if the string view contains the given substring or character (public member function) |
(C++17)
|
compares two views (public member function) |
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
https://en.cppreference.com/w/cpp/string/basic_string_view/starts_with