std::basic_string<CharT,Traits,Allocator>::contains - cppreference.com (original) (raw)

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

  3. A null-terminated character string s.

All three overloads are equivalent to return find(x) != npos;, where x is the parameter.

[edit] 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

[edit] Return value

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

[edit] Notes

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

[edit] Example

#include #include #include #include #include   template void test_substring(const std::string& str, SubstrType subs) { constexpr char delim = std::is_scalar_v ? ''' : '"'; 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] | | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | checks if the string ends with the given suffix (public member function) [edit] | | | finds the first occurrence of the given substring (public member function) [edit] | | | returns a substring (public member function) [edit] | | | checks if the string view contains the given substring or character (public member function of std::basic_string_view<CharT,Traits>) [edit] |