Question

C++ vector size 新手不知道这个编译错误为什么

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

class Solution {
public:
vector<int> twoSum(vector<int> &numbers, int target) {
vector<int> result;
vector<int>::size_type i, j;
int find = 0;
cout << numbers.size; //这里会报错
错误 1 error C3867: “std::vector<int,std::allocator<_Ty>>::size”: 函数调用缺少参数列表；请使用“&std::vector<int,std::allocator<_Ty>>::size”创建指向成员的指针
for (i = 0; i < numbers.size; i++)
{
for (j = i+1; j < numbers.size;j++)
if (numbers[i] + numbers[j] == target)
{
find = 1;
result.push_back[i];
result.push_back[j];
break;
}
if (find)
break;
}

return result;

}
};

int main()
{
vector<int> numbers;
int number;
while (cin >> number)
{
numbers.push_back(number);
}

cout << "Input the target" << endl;
int target;
cin >> target;
Solution s;
vector<int>result;
result = s.twoSum(numbers, target);
for (int i = 0; i < result.size; i++)
{
cout << result[i]<<endl;
}

}

Answer 1

要访问容器里的元素要用迭代器

for (vector<int>::iterator i = result.begin(); i != result.end(); ++i) {
  cout << *i <<endl;
}

如果你的编译器支持c++11标准，就更简单：

for (auto e : result) {
  cout << e <<endl;
}

追问

嗯，谢谢。。

Answer 2

class Window_mgr
{
public:
	typedef vector<Screen>::size_type ScreenIndex;
	Window_mgr();
	void clear(ScreenIndex);
	ScreenIndex addscreen(const Screen &);
	~Window_mgr();
private:
	vector<Screen> screens{Screen(10,20)};
};