#include <iostream>
using namespace std;
#include <vector>
#include<string>
int main()
{
vector<int> v0(5);
for (int i = 0; i < v0.size(); i++)
cout << v0[i] << ' ';
cout << endl;
vector<int> v1(10, 9);
vector<int> v2(v1.begin(), v1.end());
for (int i = 0; i < v1.size(); i++)
{
cout << v1[i] << ' ';
}
cout << endl;
vector<int>::iterator it = v2.begin();
while (it != v2.end())
{
cout << *it << ' ';
it++;
}
cout << endl;
int a[] = { 1, 2, 3, 4, 5 };
vector<int> v3(a, a + sizeof(a) / sizeof(int));
for (int i = 0; i < v3.size(); i++)
cout << v3[i] << ' ';
cout << endl;
// string类型 /
vector<string> v4(3, "abc");
for (int i = 0; i < v4.size(); i++)
cout << v4[i] << ' ';
cout << endl;
vector<string> v5(v4);
for (int i = 0; i < v5.size(); i++)
cout << v5[i] << ' ';
cout << endl;
//for (vector<string>::iterator it = v5.begin(); it != v5.end(); it++)
for (auto it = v5.begin(); it != v5.end(); it++)
cout << *it << ' ';
cout << endl;
//vector<string>::reverse_iterator rit = v5.rbegin();
auto rit = v5.rbegin();
while (rit != v5.rend())
{
cout << *rit << ' ';
rit++;
}
cout << endl;
return 0;
}
//void PrintVector(const vector<int>& v)
//{
// // const对象使用const迭代器进行遍历打印
// vector<int>::const_iterator it = v.begin();
// while (it != v.end())
// {
// cout << *it << " ";
// ++it;
// }
// cout << endl;
//}
// 将有效元素个数设置为n个,如果时增多时,增多的元素使用data进行填充
// 注意:resize在增多元素个数时可能会扩容;
//resize在开空间的同时还会进行初始化, resize出的多余空间若未赋值,初始化为0(vs)
vector<int> v;
for (int i = 0; i < 10; i++)
v.push_back(i);
for (auto ch : v)
cout << ch << ' ';
cout << endl;
v.resize(5);
for (auto ch : v)
cout << ch << ' ';
cout << endl;
v.resize(8,99);
for (auto ch : v)
cout << ch << ' ';
cout << endl;
v.resize(12);
for (auto ch : v)
cout << ch << ' ';
cout << endl;
for (auto ch : v)
{
ch += 1;
cout << ch << ' ';
}
cout << endl;
//vector<int>::iterator it = v.begin();
auto it = v.begin();
while (it != v.end())
{
cout << *it << ' ';
it++;
}
cout << endl;
//vector<int>::reverse_iterator rit = v.rbegin();
auto rit = v.rbegin();
while (rit != v.rend())
{
*rit += 1;
cout << *rit << ' ';
rit++;
}
return 0;
}
int main()
{
// 测试vector的默认扩容机制
// vs:按照1.5倍方式扩容
// linux:按照2倍方式扩容
vector<int> v;
//v.reserve(100);预先扩容
int sz = v.capacity();
cout << "Inite capacity:" << sz << endl;
for (int i = 0; i < 100; i++)
{
v.push_back(i);
if (sz != v.capacity())
{
sz = v.capacity();
cout << "Change capacity:i:" << sz << endl;
}
}
return 0;
}
往vector中插入元素时,如果大概已经知道要存放多少个元素可以通过reserve方法提前将容量设置好,避免边插入边扩容效率低。
// operator[]+index 和 C++11中vector的新式for+auto的遍历
// vector使用这两种遍历方式是比较便捷的
int main()
{
// 使用列表方式初始化,C++11新语法
//vector<int> v{ 1, 2, 3, 4 };
vector<int> v;
v.push_back(1);
v.push_back(2);
v.push_back(3);
v.push_back(4);
v.push_back(5);
v.push_back(6);
for (auto ch : v)
cout << ch << ' ';
cout << endl;
v.pop_back();
v.pop_back();
for (auto ch : v)
cout << ch << ' ';
cout << endl;
vector<int> swapv;
swapv.swap(v);
for (size_t i = 0; i < swapv.size(); ++i)
cout << swapv[i] << " ";
cout << endl;
// 2. 使用迭代器遍历
auto it = swapv.begin();
while (it != swapv.end())
{
cout << *it << " ";
++it;
}
cout << endl;
// 3. 使用范围for遍历
for (auto ch : swapv)
cout << ch << " ";
cout << endl;
return 0;
}
void TestVector()
{
// 使用列表方式初始化,C++11新语法
vector<int> v{ 1, 2, 3, 4, 3 };
// 在指定位置前插入值为val的元素,比如:3之前插入30,如果没有则不插入
// 1. 先使用find查找3所在位置(删除第一个3)
// 注意:vector没有提供find方法,如果要查找只能使用STL提供的全局find
auto pos = find(v.begin(), v.end(), 3);
if (pos != v.end())
{
// 2. 在pos位置之前插入30
v.insert(pos, 30);
}
vector<int>::iterator it = v.begin();
while (it != v.end())
{
cout << *it << " ";
++it;
}
cout << endl;
pos = find(v.begin(), v.end(), 3);
// 删除pos位置的数据
v.erase(pos);
it = v.begin();
while (it != v.end()) {
cout << *it << " ";
++it;
}
cout << endl;
}
int main()
{
TestVector();
return 0;
}