std::basic_string<CharT,Traits,Allocator>::contains

 

C++

Compiler support

Freestanding and hosted

Language

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Technical specifications

Symbols index

External libraries

 

Strings library

Null-terminated strings

Byte strings

Multibyte strings

Wide strings

Classes

basic_string

basic_string_view (C++17)

char_traits

 

std::basic_string

Member functions basic_string::basic_string basic_string::operator= basic_string::assign basic_string::get_allocator Element access basic_string::at basic_string::operator[] basic_string::front (C++11) basic_string::back (C++11) basic_string::data basic_string::c_str basic_string::operator  basic_string_view (C++17) Iterators basic_string::beginbasic_string::cbegin (C++11) basic_string::endbasic_string::cend (C++11) basic_string::rbeginbasic_string::crbegin (C++11) basic_string::rendbasic_string::crend (C++11) Capacity basic_string::empty basic_string::sizebasic_string::length basic_string::max_size basic_string::reserve basic_string::capacity basic_string::shrink_to_fit (C++11)   Operations basic_string::clear basic_string::insert basic_string::erase basic_string::push_back basic_string::pop_back (C++11) basic_string::append basic_string::operator+= basic_string::compare basic_string::starts_with (C++20)   basic_string::ends_with (C++20) basic_string::contains (C++23) basic_string::replace basic_string::substr basic_string::copy basic_string::resize basic_string::resize_and_overwrite (C++23) basic_string::swap

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

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 c.

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
c	-	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:

__cpp_lib_string_contains

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 (C++20)	checks if the string starts with the given prefix (public member function)
ends_with (C++20)	checks if the string ends with the given suffix (public member function)
find	find characters in the string (public member function)
substr	returns a substring (public member function)
contains (C++23)	checks if the string view contains the given substring or character (public member function of std::basic_string_view<CharT,Traits>)