[C++STL]vector容器用法介绍

Posted 2021-06-27 Wecccccccc

代码如下：

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

void printVector(vector<int >&v)
{
	for (vector<int>::iterator it = v.begin(); it != v.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;
}

void test01()
{
	vector<int>v1;
	for (int i = 0; i < 10; i++)
	{
		v1.push_back(i);
	}
	printVector(v1);

	vector<int>v2(v1.begin(), v1.end());
	printVector(v2);

	vector<int>v3(10, 100);
	printVector(v3);

	vector<int>v4(v3);
	printVector(v4);
}


int main()
{
	test01();
	
	return 0;
}

测试结果:

总结:
vector的多种构造方式没有可比性，灵活使用即可。

代码如下：

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

void printVector(vector<int >&v)
{
	for (vector<int>::iterator it = v.begin(); it != v.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;
}

void test01()
{
	vector<int>v1;
	for (int i = 0; i < 10; i++)
	{
		v1.push_back(i);
	}
	printVector(v1);

	vector<int>v2;
	v2 = v1;
	printVector(v2);

	vector<int>v3;

	v3.assign(v1.begin(), v1.end());
	printVector(v3);

	vector<int>v4;
	v4.assign(10, 100);
	printVector(v4);
}


int main()
{
	test01();
	
	return 0;
}

测试结果:

总结:
vector赋值方式比较简单，使用operator=，或者assign都可以。

代码如下:

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

void printVector(vector<int >&v)
{
	for (vector<int>::iterator it = v.begin(); it != v.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;
}

void test01()
{
	vector<int> v1;
	for (int i = 0; i < 10; i++)
	{
		v1.push_back(i);
	}
	printVector(v1);

	if (v1.empty())
	{
		cout << "v1为空" << endl;
	}
	else
	{
		cout << "v1不为空" << endl;
		cout << "v1 capacity = " << v1.capacity() << endl;
		cout << "v1 size = " << v1.size() << endl;
	}

	v1.resize(15, 10);
	printVector(v1);

	v1.resize(5);
	printVector(v1);
}


int main()
{
	test01();
	
	return 0;
}

测试结果:

总结:

代码如下：

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

void printVector(vector<int >&v)
{
	for (vector<int>::iterator it = v.begin(); it != v.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;
}

void test01()
{
	vector<int>v1;
	v1.push_back(10);
	v1.push_back(20);
	v1.push_back(30);
	v1.push_back(40);
	v1.push_back(50);
	printVector(v1);

	v1.pop_back();
	printVector(v1);

	v1.insert(v1.begin(), 100);
	printVector(v1);

	v1.insert(v1.begin(), 2, 1000);
	printVector(v1);

	v1.erase(v1.begin());
	printVector(v1);

	//清空
	v1.erase(v1.begin(), v1.end());
	
	v1.clear();
	printVector(v1);


}


int main()
{
	test01();
	
	return 0;
}

测试结果：

总结:

代码如下:

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

void printVector(vector<int >&v)
{
	for (vector<int>::iterator it = v.begin(); it != v.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;
}

void test01()
{
	vector<int>v1;
	for (int i = 0; i < 10; i++)
	{
		v1.push_back(i);
	}

	for (int i = 0; i < v1.size(); i++)
	{
		cout << v1[i] << " ";
	}
	cout << endl;

	for (int i = 0; i < v1.size(); i++)
	{
		cout << v1.at(i) << " ";
	}
	cout << endl;

	cout << "v1 front elem = " << v1.front() << endl;
	cout << "v1 final elem = " << v1.back() << endl;


}


int main()
{
	test01();
	
	return 0;
}

测试结果:

总结:

代码如下:

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

void printVector(vector<int >&v)
{
	for (vector<int>::iterator it = v.begin(); it != v.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;
}

void test01()
{
	vector<int>v1;
	for (int i = 0; i < 10; i++)
	{
		v1.push_back(i);
	}
	printVector(v1);

	vector<int>v2;
	for (int i = 10; i > 0; i--)
	{
		v2.push_back(i);
	}
	printVector(v2);

	//互换容器
	cout << "互换后" << endl;
	v1.swap(v2);
	printVector(v1);
	printVector(v2);


}

void test02()
{
	vector<int>v;
	for (int i = 0; i < 100000; i++)
	{
		v.push_back(i);
	}

	cout << "v capacity = " << v.capacity() << endl;
	cout << "v size = " << v.size() << endl;

	v.resize(3);

	cout << "v capacity = " << v.capacity() << endl;
	cout << "v size = " << v.size() << endl;

	//收缩内存
	vector<int>(v).swap(v);

	cout << "v capacity = " << v.capacity() << endl;
	cout << "v size = " << v.size() << endl;


}


int main()
{
	test01();
	test02();
	return 0;
}

测试结果:

总结:

代码如下：

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

void printVector(vector<int >&v)
{
	for (vector<int>::iterator it = v.begin(); it != v.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;
}

void test01()
{
	vector<int>v;
	/*v.reserve(100000);*/

	int num = 0;
	int *p = nullptr;
	for (int i = 0; i < 100000; i++)
	{
		v.push_back(i);
		if (p != &v[0])
		{
			p = &v[0];
			num++;
		}
	}
	cout << "num = " << num << endl;

}


	
int main()
{
	test01();
	return 0;
}

测试结果：

代码如下：

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

void printVector(vector<int >&v)
{
	for (vector<int>::iterator it = v.begin(); it != v.end(); it++)
	{
		cout << *it << " ";
	}
	cout << endl;
}

void test01()
{
	vector<int>v;
	v.reserve(100000);

	int num = 0;
	int *p = nullptr;
	for (int i = 0; i < 100000; i++)
	{
		v.push_back(i);
		if (p != &v[0])
		{
			p = &v[0];
			num++;
		}
	}
	cout << "num = " << num << endl;

}


	
int main()
{
	test01();
	return 0;
}

测试结果：

总结: