std::vector::resize
void resize( size_type count, T value = T() ); | | (until C++11) |
|---|---|---|
void resize( size_type count ); | (1) | (since C++11) |
void resize( size_type count, const value_type& value ); | (2) | (since C++11) |
调整容器的大小以包含count元素。
如果当前大小大于count，容器被简化为第一个容器。count元素。
If the current size is less than count, additional elements are appended and initialized with copies of value. | (until C++11) |
|---|---|
If the current size is less than count, 1) additional default-inserted elements are appended 2) additional copies of value are appended | (since C++11) |
参数
count | - | new size of the container |
|---|---|---|
value | - | the value to initialize the new elements with |
类型要求
-T必须满足MoveInsertable和DefaultInsertable的要求，才能使用过载%281%29。
T必须满足CopyInsertable的要求才能使用过载%282%29。
返回值
%280%29
复杂性
当前大小与count...
例外
如果引发异常，则此函数不会影响%28强例外保证29%。
In overload (1), if T's move constructor is not noexcept and T is not CopyInsertable into *this, vector will use the throwing move constructor. If it throws, the guarantee is waived and the effects are unspecified. | (since C++11) |
|---|
注记
如果重载%281%29中的值初始化是不可取的，例如，如果不需要非类类型的元素，并且不需要零输出，则可以通过提供自定义分配器：：构造...
当调整到较小的大小时，向量容量永远不会减少，因为这将使所有迭代器失效，而不仅仅是那些被POP的等价序列所失效的迭代器。[医]回传%28%29次电话。
例
二次
#include <iostream>
#include <vector>
int main()
{
std::vector<int> c = {1, 2, 3};
std::cout << "The vector holds: ";
for(auto& el: c) std::cout << el << ' ';
std::cout << '\n';
c.resize(5);
std::cout << "After resize up 5: ";
for(auto& el: c) std::cout << el << ' ';
std::cout << '\n';
c.resize(2);
std::cout << "After resize down to 2: ";
for(auto& el: c) std::cout << el << ' ';
std::cout << '\n';
}二次
产出：
二次
The vector holds: 1 2 3
After resize up 5: 1 2 3 0 0
After resize down to 2: 1 2二次
另见
size | returns the number of elements (public member function) |
|---|---|
insert | inserts elements (public member function) |
erase | erases elements (public member function) |
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