NAME¶

std::basic_string::contains - std::basic_string::contains

Synopsis¶

constexpr bool
contains( std::basic_string_view<CharT,Traits> sv ) const (1) (since C++23)
noexcept;
constexpr bool (2) (since C++23)
contains( CharT ch ) const noexcept;
constexpr bool (3) (since C++23)
contains( const CharT* s ) const;

Checks if the string contains the given substring. The substring 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 are equivalent to return find(x) != npos;, 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 contains the provided substring, false otherwise.

Notes¶

Feature-test macro Value Std Feature
__cpp_lib_string_contains 202011L (C++23) contains functions

Example¶

// Run this code

#include <iomanip>
#include <iostream>
#include <string>
#include <string_view>
#include <type_traits>

template<typename SubstrType>
void test_substring(const std::string& str, SubstrType subs)
{
constexpr char delim = std::is_scalar_v<SubstrType> ? '\'' : '\"';
std::cout << std::quoted(str)
<< (str.contains(subs) ? " contains "
: " does not contain ")
<< std::quoted(std::string{subs}, delim) << '\n';
}

int main()
{
using namespace std::literals;

auto helloWorld = "hello world"s;

test_substring(helloWorld, "hello"sv);
test_substring(helloWorld, "goodbye"sv);
test_substring(helloWorld, 'w');
test_substring(helloWorld, 'x');
}

Output:¶

"hello world" contains "hello"
"hello world" does not contain "goodbye"
"hello world" contains 'w'
"hello world" does not contain 'x'

See also¶

starts_with checks if the string starts with the given prefix
(C++20) (public member function)
ends_with checks if the string ends with the given suffix
(C++20) (public member function)
find finds the first occurrence of the given substring
(public member function)
substr returns a substring
(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>)