记一次简单的完全清空vector申请的内存空间的操作

最新推荐文章于 2025-08-31 17:30:44 发布

原创最新推荐文章于 2025-08-31 17:30:44 发布 · 972 阅读

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本文通过一个具体的C++示例展示了如何使用clear和shrink_to_fit函数来管理std::vector容器的大小与容量，特别关注了在进行多次容量调整后的实际效果。

使用clear函数后再使用一次shrink_to_fit函数，具体效果详见以下代码和截图。

#include<iostream>
#include<vector>
using namespace std;

int main(){
    vector<bool> flags(5);
    flags[0] = true;
    flags[2] = true;
    flags[4] = true;
    cout << "flags's size: " << flags.size() << ", flags's capacity: " << flags.capacity() << "\n";
    for (int i = 0; i < 5; i++){
        cout << flags[i] << "  ";
    }
    cout << "\n";
    flags.push_back(true);
    cout << "flags's size: " << flags.size() << ", flags's capacity: " << flags.capacity() << "\n";
    flags.shrink_to_fit();
    cout << "flags's size: " << flags.size() << ", flags's capacity: " << flags.capacity() << "\n";
    flags.clear();
    cout << "flags's size: " << flags.size() << ", flags's capacity: " << flags.capacity() << "\n";
    flags.shrink_to_fit();
    cout << "flags's size: " << flags.size() << ", flags's capacity: " << flags.capacity() << "\n";
    return 0;
}