问题描述
我声明了一个向量并尝试放置大小和值并打印它
I declared a vector and trying to put size and values and printing it
#include<iostream>
#include<vector>
using namespace std;
int main()
{
int s;
cin>>s; //taking size of vector
vector <int> arr(s);
int input;
while (cin >> input)
{arr.push_back(input);} //inserting the values in array
for(int i=0;i<s;i++)
cout<<" "<<arr[i]; //printing the values
}
我的输入5
1 2 3 4 5
预期输出
1 2 3 4 5
电流输出0 0 0 0 0
Current output 0 0 0 0 0
推荐答案
这一行:
vector <int> arr(s);
使 arr 的大小为 s.它将具有默认初始化为 0 的 s 元素.然后您正在对这个向量执行 push_back，这将 additional 元素添加到矢量.
makes arr have the size s. It will have s elements that have been default-initialized to 0. Then you are doing push_back on this vector, which adds additional elements into the vector.
当您打印出第一个 s 元素时，您看不到从 cin 中读取的值，而是从 sarr 声明中创建的初始值.
When you print out the first s elements, you are not seeing the values that were read from cin, but the s number of initial values created in the declaration of arr.
要解决这个问题，要么在声明 arr 时不要给出大小，要么只使用 arr[i] = input; 而不是 push_back() 在循环中.
To fix this, either don't give a size when you declare arr, or else just use arr[i] = input; instead of push_back() in the loop.
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