std::erase, std::erase_if(std::basic_string)
From cppreference.com
< cpp | string | basic string
C++
Feature test macros (C++20)
Concepts library (C++20)
Metaprogramming library (C++11)
Ranges library (C++20)
Filesystem library (C++17)
Concurrency support library (C++11)
Execution control library (C++26)
std::basic_string
Literals Helper classes Deduction guides (C++17)
(C++23)
(DR*)
(DR*)
(C++23)
(DR*)
(C++23)
(C++23)
(C++20)
(C++20)
(C++23)
erase(std::basic_string)erase_if(std::basic_string)
(C++20)(C++20)
(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)
(C++11)(C++11)(C++11)
(C++11)(C++11)
(C++14)
(C++11)
Defined in header
<string>
(1)
template< class CharT, class Traits, class Alloc, class U >
(since C++20) constexpr typename std::basic_string <CharT, Traits, Alloc>::size_type
(until C++26)
template< class CharT, class Traits, class Alloc, class U = CharT >
(since C++26)
constexpr typename std::basic_string <CharT, Traits, Alloc>::size_type
template< class CharT, class Traits, class Alloc, class Pred >
(2)
(since C++20)
constexpr typename std::basic_string <CharT, Traits, Alloc>::size_type
1) Erases all elements that compare equal to value from the container c. Equivalent to
auto it = std::remove(c.begin(), c.end(), value);
auto r = c.end() - it;
c.erase(it, c.end());
return r;.
auto r = c.end() - it;
c.erase(it, c.end());
return r;.
2) Erases all elements that satisfy the predicate pred from the container c. Equivalent to
auto it = std::remove_if (c.begin(), c.end(), pred);
auto r = c.end() - it;
c.erase(it, c.end());
return r;.
auto r = c.end() - it;
c.erase(it, c.end());
return r;.
[edit] Parameters
c
-
container from which to erase
value
-
value to be removed
pred
-
unary predicate which returns true if the element should be erased.
The expression pred(v) must be convertible to bool for every argument v of type (possibly const) CharT, regardless of value category, and must not modify v. Thus, a parameter type of CharT&is not allowed, nor is CharT unless for CharT a move is equivalent to a copy(since C++11).
[edit] Return value
The number of erased elements.
[edit] Complexity
Linear.
Notes
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_algorithm_default_value_type |
202403 |
(C++26) | List-initialization for std::erase
|
[edit] Example
Run this code
#include <iomanip> #include <iostream> #include <string> int main() { std::string word{"startling"}; std::cout << "Initially, word = " << std::quoted (word) << '\n'; std::erase (word, 'l'); std::cout << "After erase 'l': " << std::quoted (word) << '\n'; auto erased = std::erase_if (word, [](char x) { return x == 'a' or x == 'r' or x == 't'; }); std::cout << "After erase all 'a', 'r', and 't': " << std::quoted (word) << '\n'; std::cout << "Erased symbols count: " << erased << '\n'; #if __cpp_lib_algorithm_default_value_type std::erase (word, {'g'}); std::cout << "After erase {'g'}: " << std::quoted (word) << '\n'; #endif }
Possible output:
Initially, word = "startling"
After erase 'l', word = "starting"
After erase all 'a', 'r', and 't': "sing"
Erased symbols count: 4
After erase {'g'}: "sin"