C/C++ :: Making Addition Loop?

What my ultimate goal here is to make a program that asks the user how many numbers they would like to add followed by asking the user what numbers they want to add. I want the amount of numbers they can add to be infinite and have the loop continue adding the numbers until it reaches the final number. I just need to know how to do this.

Here's my code:

#include <iostream>
#include <string>
using namespace std;
int main() {
//variables
int amount;
float num;
float sum;

[code]....