Calculating days between two dates in C

C style would be more like

Code:

while (year1 < year2)
  days_until += 365 + if_leap(year1++);

more like

Code:

int i;
for (i = year1; i < year2; i++)
  days_until += 365 + if_leap(i);

Unless you actually want to modify the contents of year1, that is.