std::vector<T,Allocator>::shrink_to_fit
| void shrink_to_fit(); |
(C++11 起) (C++20 前) |
|
| constexpr void shrink_to_fit(); |
(C++20 起) | |
请求移除未使用的容量。
它是减少 capacity() 到 size()非强制性请求。请求是否达成依赖于实现。
若发生重分配，则所有迭代器，包含尾后迭代器，和所有到元素的引用都被非法化。若不发生重分配，则没有迭代器或引用被非法化。
参数
（无）
| 类型要求 | ||
-T 必须满足可移动插入 (MoveInsertable) 的要求。
|
返回值
（无）
复杂度
至多与容器大小成线性。
注解
若 T 的移动构造函数以外的操作抛出异常，则无效果。
示例
运行此代码
#include <iostream> #include <vector> int main() { std::vector<int> v; std::cout << "Default-constructed capacity is " << v.capacity() << '\n'; v.resize(100); std::cout << "Capacity of a 100-element vector is " << v.capacity() << '\n'; v.resize(50); std::cout << "Capacity after resize(50) is " << v.capacity() << '\n'; v.shrink_to_fit(); std::cout << "Capacity after shrink_to_fit() is " << v.capacity() << '\n'; v.clear(); std::cout << "Capacity after clear() is " << v.capacity() << '\n'; v.shrink_to_fit(); std::cout << "Capacity after shrink_to_fit() is " << v.capacity() << '\n'; for (int i = 1000; i < 1300; ++i) v.push_back(i); std::cout << "Capacity after adding 300 elements is " << v.capacity() << '\n'; v.shrink_to_fit(); std::cout << "Capacity after shrink_to_fit() is " << v.capacity() << '\n'; }
可能的输出：
Default-constructed capacity is 0 Capacity of a 100-element vector is 100 Capacity after resize(50) is 100 Capacity after shrink_to_fit() is 50 Capacity after clear() is 50 Capacity after shrink_to_fit() is 0 Capacity after adding 300 elements is 512 Capacity after shrink_to_fit() is 300
参阅
| 返回容纳的元素数 (公开成员函数) | |
| 返回当前存储空间能够容纳的元素数 (公开成员函数) |