Calculate the number of business days between two dates?

Question

In C#, how can I calculate the number of business (or weekdays) days between two dates?

Answer 1

I came up with the following solution

var dateStart = new DateTime(2019,01,10);
var dateEnd = new DateTime(2019,01,31);

var timeBetween = (dateEnd - dateStart).TotalDays + 1;
int numberOf7DayWeeks = (int)(timeBetween / 7);
int numberOfWeekendDays = numberOf7DayWeeks * 2;
int workingDays =(int)( timeBetween - numberOfWeekendDays);

if(dateStart.DayOfWeek == DayOfWeek.Saturday || dateEnd.DayOfWeek == DayOfWeek.Sunday){
    workingDays -=2;
}       
if(dateStart.DayOfWeek == DayOfWeek.Sunday || dateEnd.DayOfWeek == DayOfWeek.Saturday){
    workingDays -=1;
}