C++ primer(第五版） 练习 3.21 个人code


C++ primer(第五版） 练习 3.21

题目：请使用迭代器重做3.3.3节的第一个练习 （就是 练习3.16：编写一段程序，把练习3.13中vector对象的容量和具体内容输出出来）

答：

#include <iostream>
#include <vector>
#include <string>

using std::cout;
using std::cin;
using std::endl;
using std::string;
using std::vector;

int main()
{
vector<int> v1;
vector<int> v2(10);
vector<int> v3(10, 42);
vector<int> v4{ 10 };
vector<int> v5{ 10, 42 };
vector<string> v6{ 10 };
vector<string> v7{ 10, "hi" };

cout << "v1的容量是：" << v1.size() << endl;
cout << "v2的容量是：" << v2.size() << endl;
cout << "v3的容量是：" << v3.size() << endl;
cout << "v4的容量是：" << v4.size() << endl;
cout << "v5的容量是：" << v5.size() << endl;
cout << "v6的容量是：" << v6.size() << endl;
cout << "v7的容量是：" << v7.size() << endl;
cout << endl ;
cout << "v1里的元素内容如下：" << endl;
if (v1.begin() == v1.end())
{
cout << "v1容器里没有元素" << endl;
}
else
{
for (auto b = v1.begin(); b != v1.end(); b++)
cout << *b << " ";
}
cout << endl ;

cout << "v2里的元素内容如下：" << endl;
if (v2.begin() == v2.end())
{
cout << "v2容器里没有元素" << endl;
}
else
{
for (auto b = v2.begin(); b != v2.end(); b++)
cout << *b << " ";
}
cout << endl;

cout << "v3里的元素内容如下：" << endl;
if (v3.begin() == v3.end())
{
cout << "v3容器里没有元素" << endl;
}
else
{
for (auto b = v3.begin(); b != v3.end(); b++)
cout << *b << " ";
}
cout << endl ;

cout << "v4里的元素内容如下：" << endl;
if (v4.begin() == v4.end())
{
cout << "v4容器里没有元素" << endl;
}
else
{
for (auto b = v4.begin(); b != v4.end(); b++)
cout << *b << " ";
}
cout << endl ;

cout << "v5里的元素内容如下：" << endl;
if (v5.begin() == v5.end())
{
cout << "v5容器里没有元素" << endl;
}
else
{
for (auto b = v5.begin(); b != v5.end(); b++)
cout << *b << " ";
}
cout << endl ;

cout << "v6里的元素内容如下：" << endl;
if (v6.begin() == v6.end())
{
cout << "v6容器里没有元素" << endl;
}
else
{
for (auto b = v6.begin(); b != v6.end(); b++)
cout << *b << " ";
}
cout << endl ;

cout << "v7里的元素内容如下：" << endl;
if (v7.begin() == v7.end())
{
cout << "v7容器里没有元素" << endl;
}
else
{
for (auto b = v7.begin(); b != v7.end(); b++)
cout << *b << " ";
}
cout << endl ;

return 0;

}

执行结果图：