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

 

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std::basic_string

成员函数 basic_string::basic_string basic_string::~basic_string basic_string::operator= basic_string::assign basic_string::assign_range (C++23)   basic_string::get_allocator 元素访问 basic_string::at basic_string::operator[] basic_string::front (DR*) basic_string::back (DR*) basic_string::data basic_string::c_str basic_string::operator  basic_string_view (C++17) 迭代器 basic_string::beginbasic_string::cbegin (C++11) basic_string::endbasic_string::cend (C++11) basic_string::rbeginbasic_string::crbegin (C++11) basic_string::rendbasic_string::crend (C++11) 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

修改器 basic_string::clear basic_string::insert basic_string::insert_range (C++23) basic_string::erase basic_string::push_back basic_string::pop_back (DR*) basic_string::append basic_string::append_range (C++23) basic_string::operator+= basic_string::replace basic_string::replace_with_range (C++23) basic_string::copy basic_string::resize basic_string::resize_and_overwrite (C++23)  basic_string::swap 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 (DR*) 操作 basic_string::compare basic_string::starts_with (C++20) basic_string::ends_with (C++20) basic_string::contains (C++23) basic_string::substr

常量 basic_string::npos 非成员函数 operator+ swap(std::basic_string) 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<=> (直到 C++20)(直到 C++20)(直到 C++20)(直到 C++20)(直到 C++20)(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) 字面量 operator""s (C++14) 辅助类 hash<std::basic_string> (C++11) 推导指引 (C++17)

 

定义于头文件 <string>
	(1)
template< class CharT, class Traits, class Alloc, class U > constexpr std::basic_string<CharT, Traits, Alloc>::size_type     erase( std::basic_string<CharT, Traits, Alloc>& c, const U& value );			(C++20 起) (直到 C++26)
template< class CharT, class Traits, class Alloc, class U = CharT > constexpr std::basic_string<CharT, Traits, Alloc>::size_type     erase( std::basic_string<CharT, Traits, Alloc>& c, const U& value );			(C++26 起)
template< class CharT, class Traits, class Alloc, class Pred > constexpr std::basic_string<CharT, Traits, Alloc>::size_type     erase_if( std::basic_string<CharT, Traits, Alloc>& c, Pred pred );		(2)	(C++20 起)

1) 从容器擦除所有与 value 比较相等的元素。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) 从容器擦除所有满足谓词 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	-	从中擦除元素的容器
value	-	要移除的值
pred	-	一元谓词，若元素应被擦除则返回 true 。 表达式 pred(v) 必须可转换为 bool ，对每个 v 的实参，类型为（可能为 const ） CharT ，忽略值类别，且不得修改 v 。 故不允许 CharT& 的形参类型，亦不允许 CharT ，除非对 CharT 移动等价于复制(C++11 起) 。 ​

返回值

被擦除元素的数量。

复杂度

线性。

注解

特性测试 宏	值	Std	特性
__cpp_lib_algorithm_default_value_type	202403	(C++26)	列表初始化 算法 (1)

示例

运行此代码

#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
}

可能的输出

Initially, word = "startling"
After erase 'l', word = "starting"
After erase all 'a', 'r', and 't': "sing"
Erased symbols count: 4
After erase {'g'}: "sin"

参见

removeremove_if	移除满足特定标准的元素 (函数模板)
ranges::removeranges::remove_if (C++20)(C++20)	移除满足特定标准的元素 (算法函数对象)