gistfile1.txt

int num = 0;

void addOne(int& n)
{
  n++;
}

// another way to write addOne

int addOne(int n)
{
  return n+1;
}

// so instead of calling addOne(num) it'd be num = addOne(num);

do
{
  addOne(num);
} while(num<100);

// in another case

int num = 100;

void addOne(int& n)
{
  n++;
}

do
{
  addOne(num);
} while(num<100);

// num would end up 101

// basically do is this:

addOne(num);
while(true) {
 if(num<100)
   return;

 addOne(num);
}