References are another name

int &r = count; makes r another name for count; the arrow shows what it refers to. Changing r changes count.

bump takes an int &, so inside it n is main's count, and the change sticks. It's what the pointer version did in C, with no & and * at every use.

#include <iostream>

void bump(int &n) {
    n += 10;
}

int main() {
    int count = 1;
    int &r = count;
    r = 5;
    bump(count);
    std::cout << count << "\n";
    return 0;
}

Output:

15

From the lesson: References and functions