c# - Calculating using a class, money minus bill -

when calculate change (money - bill), appears zero (0). don't know got wrong.

this class :

class changecalc {     int a, b;      public int b     {         { return b; }         set { b = value; }     }      public int     {         { return a; }         set { = value; }     }     public changecalc()     {         = 0;         b = 0;     }              public changecalc(int c,int d)     {         c = a;         d = b;     }     public int calculate()     {        //this money-bill         return - b;     }  } 

in form :

if (int.parse(txtboxmoney.text) >= int.parse(txtboxbill.text)) {     //display change     changecalc aa = new changecalc(int.parse(txtboxmoney.text), int.parse(txtboxbill.text));     change.text = aa.calculate().tostring();  } else {     //error if money lower bill     txtboxmoney.clear();     change.clear();     messagebox.show("your money not enough"); } 

where did miss?

the following function updates c & d zeroes while should update backing fields, & b. leaves fields & b defaulted zeroes , hence difference zero.

public changecalc(int c,int d) {     c = a;     d = b; } 

change code follows:

public changecalc(int c,int d) {     = c;     b = d; } 

you may consider refactoring class:

1. rename fields they're readable.
2. remove backing fields (a & b). don't need backing fields current use case. compiler generate them you.

updated code:

class changecalculator {   public int money { get; set; }    public int bill { get; set; }    public changecalculator()   {      money = 0;      bill = 0;   }    public changecalculator(int money, int bill)   {      money = money;      bill = bill;   }    public int calculate()   {     return money - bill;   } }