Question

So i’ve got 3 textfields (A, B, C) where the user can only enter numbers as the keyboard is a number pad.

I’ve got a check (which a user here sorted out for me) that brings up an error if the user tries to enter more than 100 in each box.

I need a method that looks at the number entered in the textfield and then looks at the total of the 3 and then adjusts the others accordingly.

An example would be say i typed the following:

Example 1
A = 50
I would expect B to fill in with the remaining 50

Example 2
A =40 B=50 C=10

I then change A to 60. The total is now 120.
I would like it to look at B, then take 20 away so I have the following.
A=60 B=30 C=10

I’ve seen scenarios where a user has 2 textfields that he wants to total 100 but I have not seen threads that ask for 3.

Thanks

Answer 1

Let’s say you have three fields. This is pseudocode. Attach this delegate function to all 3 text areas.

// Take 3 fields
FieldA, FieldB, FieldC

// Total target to reach
TotalTarget = 100

// The total we currently have
total = FieldA + FieldB + FieldC

// Work out how much we are under by. 
// If positive, we are under. If negative, we are over.
underBy = TotalTarget - total

// Now two variables for the 'other two' fields.
if sender == FieldA:
  other1 = FieldB, other2 = FieldC
if sender == FieldB:
  other1 = FieldA, other2 = FieldC
if sender == FieldC:
  other1 = FieldA, other2 = FieldB

// Split the difference and assign to other 2 fields so they are raised or lowered the same amount.
// If under, add, if over, subtract.
other1 = other1 + overBy / 2
other2 = other2 + overBy / 2        

// This will add 1 or 0 to other2 (i.e. compensate for round-down)
other2 = other2 + overBy % 2;

If you use integer division, then you will have a rounding problem. Hint: if it’s odd, you can add one to one of the fields.

Make sure you write tests. I’ve not tried any of this, but it should work.