C++ vector向量类模板的使用及解析

冷不防 2023-09-30 15:09 13阅读 0赞

vector向量是一种**随机访问的数组类型**，提供了对数组元素的快速和随机访问，以及在序列尾部快速、随机的插入和删除操作。**其大小可变，在需要时可以改变数组大小**

**头文件要导入\#include<vector>**

**为整型值创建一个空std::vector对象可以使用这样的语句**

**std::vector<int>intvector**

**包括vector模板中有很多种方法可以调用 下面是测试源码，如需自取**

#include<iostream>
    #include<vector>
    #include<stdarg.h>
    using namespace std;
    using std::cout;
    using std::endl;
    using std::vector;
    int mai(int argc, char* argv[])
    {
    	vector<int>v1, v2;
    	v1.reserve(10);
    	v2.reserve(10);
    	v1 = vector<int>(8, 7);
    	int array[8] = { 1,1,54,24,131,42,42,1331 };
    	v2 = vector<int>(array, array + 8);
    	cout << "v1容量" << v1.capacity() << endl;
    	cout << "v2容量" << v2.capacity() << endl;
    	for (decltype(v2.size())i = 0; i < v1.size(); i++) {
    
    		cout << " " << v1[i];
    
    	}
    	cout << endl;
    	cout << "v2容量" << v2.capacity() << endl;
    	cout << "v2当前各项" << endl;
    	for (vector<int>::size_type i = 0; i < v1.size(); i++) {
    
    		cout << " " << v2[i] << endl;
    	}
    
    	cout << endl;
    	v1.resize(0);
    	cout << "v1的容量通过resize函数变成0" << endl;
    	if (!v1.empty())
    		cout << "v1容量" << v1.capacity() << endl;
    	else
    		cout << "v1是空的" << endl;
    	cout << "将v1容量扩展为8" << endl;
    	v1.resize(8);
    	cout << "v1当前各项" << endl;
    	for (decltype(v1.size())i = 0; i < v1.size(); i++)
    	{
    		cout << "" << v1[i] << endl;
    	}
    	cout << endl;
    	v1.swap(v2);
    	cout << "v1与v2交换了" << endl;
    	cout << "v1当前各项" << endl;
    	cout << "v1容量" << v1.capacity() << endl;
    	for (decltype(v1.size())i = 0; i < v1.size(); i++) {
    		cout << " " << v1[i] << endl;
    	}
    	cout << endl;
    	v1.push_back(3);
    	cout << "v1从后边加入了元素3" << endl;
    	cout << "v1容量" << v1.capacity() << endl;
    	for (decltype(v1.size())i = 0; i < v1.size(); i++)
    	{
    		cout << " " << v1[i] << endl;
    	}
    	cout << endl;
    	v1.erase(v1.end() - 2);
    	cout << "删除了倒数第二个元素" << endl;
    	cout << "v1容量" << v1.capacity() << endl;
    	cout << "v1当前各项" << endl;
    	for (vector<int>::size_type i = 0; i < v1.size(); i++) {
    		cout << " " << v1[i] << endl;
    	}
    	cout << endl;
    	v1.pop_back();
    	cout << "v1通过栈操作放走了最后的元素" << endl;
    	cout << "v1当前各项" << endl;
    	cout << "v1容量" << v1.capacity() << endl;
    	for (vector<int>::size_type i = 0; i < v1.size(); i++) {
    		cout << " " << v1[i] << endl;
    	}
    	cout << endl;
    	return 0;
    
    
    
    
    
    }