Why there are so many duplicates while loading vector-CodePudding

I need to load vector with infinite loop and to print it. Loading is over when 0 entered.

OUTPUT:

Enter numbers: 1 3 1 4 2 1 3 1 4 2 1 3 0
1 3 1 4 2 1 3 1 4 2 1 3

Code:

#include <iostream>
#include <vector>
int main()
{
    std::vector<double>vektor;
    double a;
    for(;;)
    {
      std::cout << "Enter numbers: ";
      std::cin>>a;
      if(a!=0)vektor.push_back(a);
      if(a==0)break;
    }
    for(double a:vektor)
    std::cout << a << " ";
    return 0;
}

I get this output:

Enter numbers: 1 3 1 4 2 1 3 1 4 2 1 3 0 
Enter numbers: Enter numbers: Enter numbers: Enter numbers: Enter numbers: Enter numbers: Enter numbers: Enter numbers: Enter numbers: Enter numbers: Enter numbers: Enter numbers: 1 3 1 4 2 1 3 1 4 2 1 3

Could you explain me why there are so many duplicates of string "Enter numbers: "? If I load numbers one by one I wouldn't get any duplicate, but I need to load them all in one line like in example output. How could I modify this code to do that?

CodePudding user response：

Could you explain me why there are so many duplicates of string "Enter numbers: "?

Because you are outputting Enter numbers on every loop iteration before reading a new number. Simply move that statement above the loop instead.

Also, your loop can be simplified. You are ignoring the error state of the stream after each >> call.

Try this:

#include <iostream>
#include <vector>

int main()
{
    std::vector<double>vektor;
    double a;

    std::cout << "Enter numbers: ";

    while(std::cin >> a && a != 0)
    {
      vektor.push_back(a);
    }

    for(double a: vektor)
        std::cout << a << " ";

    return 0;
}