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Re: my calculator has problems


From: umen
Subject: Re: my calculator has problems
Date: Sat, 09 Apr 2016 08:53:40 -0400

Hi,
Number1 is NSButton. result is the NSTextField. I assign string to number1 because with strings I can append other numbers and assign this new number to number1 again, then I use doubleValue to get a double from this string. It's exactly what else{} is doing at all button methods. Or there is another/better way to do that not using strings?
-------- Original Message --------
On 9 de abr de 2016 01:02, Germán Arias wrote:

Hi,

I have not clear what is "number1". But in method "-add" you assign a
string to this variable, so this become a string object. Then, later,
you call "-setDoubleValue:" at "number1" as if it was an NSTextField
object. If this is an NStextField object, then you should do (in method
"-add"):

[number1 setDoubleValue: 0];

Hope this help.
Germán

El vie, 08-04-2016 a las 15:01 -0400, umen escribió:
> Hi people,
>
> I'm trying to write a basic calculator using GNUstep+ObjC and I get stucked. I really don't know where is the problem in my code. May you help me?
>
>
> I'm sending here what I have implemented until now:
>
>
>
> @interface UCalc : NSObject
>
> {
>
> char operation; //just a char to validate the operation
>
> id number1, number2; //number1 = the current button pressed, number2
> = the old number
>
> id result; //the calculator display
>
> }
>
> - (void) Add: (id)sender;
>
> @end
>
>
>
>
>
> @implementation UCalc
>
> - (void) Add: (id)sender
>
> {
>
> operation = '+';
>
> number2 = number1; //when you press the add button the current
> number becomes the old number
>
> number1 = @"0";
>
> }
>
>
>
> - (void) Button0: (id)sender
>
> {
>
> number1 = @"0";
>
> [result setStringValue: number1];
>
> }
>
>
>
> - (void) Button1: (id)sender
>
> {
>
> //if there is no number yet
>
> if (number1 == nil || [number1 isEqual: @"0"]){
>
> [result setStringValue: @""];
>
> number1 = @"1";
>
> }
>
> //else append the current number in itself, so we can get number > 9
>
> else{
>
> number1 = [number1 stringByAppendingFormat: @"1"];
>
> }
>
> [result setStringValue: number1];
>
> }
>
>
>
>
>
> - (void) Button2: (id)sender
>
> {
>
> if (number1 == nil || [number1 isEqual: @"0"]){
>
> [result setStringValue: @""];
>
> number1 = @"2";
>
> }
>
> else{
>
> number1 = [number1 stringByAppendingFormat: @"2"];
>
> }
>
> [result setStringValue: number1];
>
> }
>
>
>
> All the others number buttons are implemented in the same way...
>
>
>
> The problem is in Equal button:
>
>
>
> - (void) Equal: (id)sender{
>
> switch(operation){
>
> case '+':
>
> //trying to do this: number1 = number2 + number1 and then print
> in the display result
>
> [number1 setDoubleValue: [number2 doubleValue] + [number1
> doubleValue]];
>
> [result setStringValue: number1];
>
> break;
>
> }
>
> }
>
>
>
> I already have created the window in Gorm, so everything is
> implemented there. The problem in this code is in the number1 =
> number2 + number1 in Equal method, I don't know why it's not assigning
> to number1 the operation correctly and then result working correctly.
> Any idea about what I'm doing wrong? Everything?
>
>
>
> Sorry my english. Thanks.
> _______________________________________________
> Discuss-gnustep mailing list
> address@hidden
> https://lists.gnu.org/mailman/listinfo/discuss-gnustep



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