You can calculate number of weekdays in crystal reports.

In report create a formula and enter the following code.

 

// This formula does not account for holidays

// I am using Shared variable so that I can use in my subreports

 

Shared DateTimeVar d1 := {Orders.Order Date};

Shared DateTimeVar d2 := {Orders.Ship Date};

DateDiff ("d", d1, d2) - 

     DateDiff ("ww", d1, d2, crSaturday) -

     DateDiff ("ww", d1, d2, crSunday)