std::erase, std::erase_if (std::basic_string)

 

C++

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功能特性测试宏 (C++20)

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类

basic_string

basic_string_view (C++17)

char_traits

 

std::basic_string

成员函数 basic_string::basic_string basic_string::operator= basic_string::assign basic_string::get_allocator 元素访问 basic_string::at basic_string::operator[] basic_string::front basic_string::back basic_string::data basic_string::c_str basic_string::operator  basic_string_view (C++17) 迭代器 basic_string::beginbasic_string::cbegin basic_string::endbasic_string::cend basic_string::rbeginbasic_string::crbegin basic_string::rendbasic_string::crend 容量 basic_string::empty basic_string::sizebasic_string::length basic_string::max_size basic_string::reserve basic_string::capacity basic_string::shrink_to_fit 操作 basic_string::clear basic_string::insert basic_string::erase basic_string::push_back basic_string::pop_back 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

搜索 basic_string::find basic_string::rfind basic_string::find_first_of basic_string::find_first_not_of basic_string::find_last_of basic_string::find_last_not_of 常量 basic_string::npos 推导指引 (C++17) 非成员函数 operator+ swap(std::basic_string) operator""s (C++14) erase(std::basic_string)erase_if(std::basic_string) (C++20)(C++20) I/O operator<<operator>> getline 比较 operator==operator!=operator<operator>operator<=operator>=operator<=> (C++20 前)(C++20 前)(C++20 前)(C++20 前)(C++20 前)(C++20) 数值转换 stoistolstoll (C++11)(C++11)(C++11) stoulstoull (C++11)(C++11)     stofstodstold (C++11)(C++11)(C++11) to_string (C++11) to_wstring (C++11) 辅助类 hash<std::string>hash<std::wstring>hash<std::u32string>hash<std::u16string>hash<std::u8string> (C++11)  (C++11)(C++11)(C++11)(C++20) hash<std::pmr::string>hash<std::pmr::wstring>hash<std::pmr::u32string>hash<std::pmr::u16string>hash<std::pmr::u8string> (C++17)(C++17)(C++17)(C++17)(C++20)

 

在标头 <string> 定义
template< class CharT, class Traits, class Alloc, class U > constexpr typename std::basic_string<CharT, Traits, Alloc>::size_type     erase( std::basic_string<CharT, Traits, Alloc>& c, const U& value );	(1)	(C++20 起)
template< class CharT, class Traits, class Alloc, class Pred > constexpr typename std::basic_string<CharT, Traits, Alloc>::size_type     erase_if( std::basic_string<CharT, Traits, Alloc>& c, Pred pred );	(2)	(C++20 起)

1) 从容器中擦除所有比较等于 value 的元素。等价于

auto it = std::remove(c.begin(), c.end(), value);
auto r = c.end() - it;
c.erase(it, c.end());
return r;

2) 从容器中擦除所有满足 pred 的元素。等价于

auto it = std::remove_if(c.begin(), c.end(), pred);
auto r = c.end() - it;
c.erase(it, c.end());
return r;

参数

c	-	要从中擦除的容器
value	-	要擦除的值
pred	-	若应该擦除元素则返回 ​true 的一元谓词。 对每个（可为 const 的） CharT 类型参数 v ，表达式 pred(v) 必须可转换到 bool，无关乎值类别，而且必须不修改 v 。从而不允许 CharT& 类型参数，亦不允许 CharT ，除非对 CharT 而言移动等价于复制 (C++11 起)。 ​

返回值

被擦除的元素数。

复杂度

线性。

示例

运行此代码

#include <iostream>
#include <numeric>
#include <string_view>
#include <string>
 
void print_container(std::string_view comment, const std::string& c)
{
    std::cout << comment << "{ ";
    for (auto x : c) {
        std::cout << x << ' ';
    }
    std::cout << "}\n";
}
 
int main()
{
    std::string cnt(10, ' ');
    std::iota(cnt.begin(), cnt.end(), '0');
    print_container("Initially, cnt = ", cnt);
 
    std::erase(cnt, '3');
    print_container("After erase '3', cnt = ", cnt);
 
    auto erased = std::erase_if(cnt, [](char x) { return (x - '0') % 2 == 0; });
    print_container("After erase all even numbers, cnt = ", cnt);
    std::cout << "Erased even numbers: " << erased << '\n';
}

输出：

Initially, cnt = { 0 1 2 3 4 5 6 7 8 9 }
After erase '3', cnt = { 0 1 2 4 5 6 7 8 9 }
After erase all even numbers, cnt = { 1 5 7 9 }
Erased even numbers: 5

参阅

removeremove_if

移除满足特定判别标准的元素 (函数模板)