NAME

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

Synopsis

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

Example

// Run this code

#include <iostream>
#include <string_view>
#include <string>

template <typename PrefixType>
void test_prefix_print(const std::string& str, PrefixType prefix)
{
std::cout << '\'' << str << "' starts with '" << prefix << "': " <<
str.starts_with(prefix) << '\n';
}

int main()
{
std::boolalpha(std::cout);
auto helloWorld = std::string("hello world");

test_prefix_print(helloWorld, std::string_view("hello"));

test_prefix_print(helloWorld, std::string_view("goodbye"));

test_prefix_print(helloWorld, 'h');

test_prefix_print(helloWorld, 'x');
}

Output:

'hello world' starts with 'hello': true
'hello world' starts with 'goodbye': false
'hello world' starts with 'h': true
'hello world' starts with 'x': false

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)