input twice

[hunterx893]

Hi, I am trying to figure out why whenever I input a number, I have to input it twice to go through the GetParam function.
Example 1: (If I input a number less than the minimum.)

Please enter the monthly payment: 0
0
Please enter the monthly payment:

Example 2: (If I input a number that is between the minimum and maximum)

Please enter the monthly payment: 5
5
5

  #include <iostream>
#include <string>

using namespace std; 

double GetParam(string prompt, double min, double max)
{
	double number;
	cout << prompt;
	cin >> number;

	while ((!(cin >> number)) || (number > max || number < min))
	{
		cin.clear(); 
		cin.ignore();
		cout << prompt; 
		cin >> number;
	}

	return number; 
}

int main()
{
	double monthpay;
	
	monthpay = GetParam("Please enter the monthly payment: ",1,100000);
	cout << monthpay << endl;
	return 0; 
}

[giblit]

remove line 10 and 17 then look closely at line 12.

[hunterx893]

I tried it and it works but I don't understand how come you remove cin >> number from line 10 and 17. In my sense, cin >> number is asking the user to input again and again until it does not satisfy the while loop and return the number.

[tmason]

Line 12 asks for the number and stores it in the double variable "number", what is the need to ask for it before the while loop or in it?