如何将 cin 值转换为向量 [英] How to cin values into a vector

问题描述

我试图让用户输入将被推入向量中的数字，然后使用函数调用来计算这些数字.

I'm trying to ask the user to enter numbers that will be pushed into a vector, then using a function call to count these numbers.

为什么这不起作用?我只能数第一个数字.

why is this not working? I'm only able to count the first number.

template <typename T>
void write_vector(const vector<T>& V)
{
   cout << "The numbers in the vector are: " << endl;
  for(int i=0; i < V.size(); i++)
    cout << V[i] << " ";
}

int main()
{
  int input;
  vector<int> V;
  cout << "Enter your numbers to be evaluated: " << endl;
  cin >> input;
  V.push_back(input);
  write_vector(V);
  return 0;
}

推荐答案

照原样，您只是读取单个整数并将其推送到您的向量中.由于您可能想要存储多个整数，因此您需要一个循环.例如，替换

As is, you're only reading in a single integer and pushing it into your vector. Since you probably want to store several integers, you need a loop. E.g., replace

cin >> input;
V.push_back(input);

与

while (cin >> input)
    V.push_back(input);

只要有要抓取的输入，它就会不断地从 cin 中拉取整数；循环继续，直到 cin 找到 EOF 或尝试输入非整数值.另一种方法是使用标记值，尽管这会阻止您实际输入该值.例如:

What this does is continually pull in ints from cin for as long as there is input to grab; the loop continues until cin finds EOF or tries to input a non-integer value. The alternative is to use a sentinel value, though this prevents you from actually inputting that value. Ex:

while ((cin >> input) && input != 9999)
    V.push_back(input);

将一直读取，直到您尝试输入 9999(或任何其他导致 cin 无效的状态)，此时循环将终止.

will read until you try to input 9999 (or any of the other states that render cin invalid), at which point the loop will terminate.

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