std::basic_string<CharT,Traits,Allocator>:: contains
From cppreference.com
<
cpp
|
string
|
basic string
|
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.
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
|
(C++20)
|
checks if the string starts with the given prefix
(public member function) |
|
(C++20)
|
checks if the string ends with the given suffix
(public member function) |
|
finds the first occurrence of the given substring
(public member function) |
|
|
returns a substring
(public member function) |
|
|
(C++23)
|
checks if the string view contains the given substring or character
(public member function of
std::basic_string_view<CharT,Traits>
)
|