Namespaces
Variants
Views
Actions

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

From cppreference.com
< cpp‎ | string‎ | basic string
 
 
 
std::basic_string
Member functions
Element access
Iterators
Capacity
Operations
basic_string::contains
(C++23)
Search
Constants
Deduction guides (C++17)
Non-member functions
I/O
Comparison
(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)
Numeric conversion
(C++11)(C++11)(C++11)
(C++11)(C++11)
(C++11)(C++11)(C++11)
(C++11)
(C++11)
Helper classes
 
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.

Contents

[edit] 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

[edit] Return value

true if the string contains the provided substring, false otherwise.

[edit] Notes

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

[edit] Example

#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'

[edit] See also

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