NAME¶

std::basic_string::starts_with - std::basic_string::starts_with

Synopsis¶

constexpr bool
starts_with( std::basic_string_view<CharT,Traits> sv ) const (1) (since C++20)
noexcept;
constexpr bool (2) (since C++20)
starts_with( CharT ch ) const noexcept;
constexpr bool (3) (since C++20)
starts_with( const CharT* s ) const;

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.

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()

Example¶

// Run this code

#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)