std::replace, std::replace_if
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在头文件 <algorithm> 中定义
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template< class ForwardIt, class T > void replace( ForwardIt first, ForwardIt last, |
(1) | |
template< class ForwardIt, class UnaryPredicate, class T > void replace_if( ForwardIt first, ForwardIt last, |
(2) | |
替换
new_value
的范围内[first, last)
满足特定条件的所有元素。第一个版本取代元素是等于old_value
,第二个版本替换元素的谓词p
回报true. 原文:
Replaces all elements satisfying specific criteria with
new_value
in the range [first, last)
. The first version replaces the elements that are equal to old_value
, the second version replaces elements for which predicate p
returns true. 目录 |
[编辑] 参数
first, last | - | 元素的范围内进行处理
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old_value | - | 的值的元素来代替
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p | - | unary predicate which returns true 如果元素的值应进行更换 . 原文: if the element value should be replaced The signature of the predicate function should be equivalent to the following: bool pred(const Type &a); The signature does not need to have const &, but the function must not modify the objects passed to it. |
new_value | - | 要使用的值作为替代品
|
类型要求 | ||
-ForwardIt 必须满足 ForwardIterator 的要求。
|
[编辑] 返回值
(无)
[编辑] 复杂度
究竟
last - first
的谓词中的应用.原文:
Exactly
last - first
applications of the predicate.[编辑] 可能的实现
版本一 |
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template<class ForwardIt, class T> void replace(ForwardIt first, ForwardIt last, const T& old_value, const T& new_value) { for (; first != last; ++first) { if (*first == old_value) { *first = new_value; } } } |
版本二 |
template<class ForwardIt, class UnaryPredicate, class T> void replace_if(ForwardIt first, ForwardIt last, UnaryPredicate p, const T& new_value) { for (; first != last; ++first) { if(p(*first)) { *first = new_value; } } } |
[编辑] 示例
下面的代码在第一次替换所有出现的888的向量整数。然后,它会取代所有的值小于555 .
原文:
The following code at first replaces all occurrences of 8 with 88 in a vector of integers. Then it replaces all values less than 5 with 55.
#include <algorithm> #include <array> #include <iostream> #include <functional> int main() { std::array<int, 10> s{5, 7, 4, 2, 8, 6, 1, 9, 0, 3}; std::replace(s.begin(), s.end(), 8, 88); for (int a : s) { std::cout << a << " "; } std::cout << '\n'; std::replace_if(s.begin(), s.end(), std::bind(std::less<int>(), std::placeholders::_1, 5), 55); for (int a : s) { std::cout << a << " "; } std::cout << '\n'; }
输出:
5 7 4 2 88 6 1 9 0 3 5 7 55 55 99 6 55 9 55 55
[编辑] 另请参阅
复制一个范围内的元素,并将满足特定条件的元素替换为另一个值 (函数模板) |