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TBaseCalc.md

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TBaseCalc

Base component with core functions for calculators. This component aims to emulate the behavior of Casio calculators and to be independent of the user interface.

Initializing the component

When adding a TBaseCalc to your form you can setup the maximum number of digits on the screen, not including the decimal separator or the minus sign.

BaseBaseCalc.Init(10);

This will allow to print numbers like:

-1234,567809

You should always initialize TBaseCalc, but when no screen size is informed, TBaseCalc assumes a 8 digits screen. You can't create an calculator with less than 8 digits. After initializing the object, you should read the calculator's screen:

BaseBaseCalc.Init(10);
PnlScreen.Caption := BaseBaseCalc.Screen; //You can user any component to display the value of the calculator's screen.

Basic Operations

To perform basic operations you can use the following commands:

12,3 + 74 - 90

BaseCalc.PushToScreen('1'); //Key [1] pressed
//You can call PnlScreen.Caption := BaseCalc.Screen to refresh the screen after pushing a value
BaseCalc.PushToScreen('2'); //Key [2] pressed
BaseCalc.PushToScreen(','); //Key [,] pressed
BaseCalc.PushToScreen('3'); //Key [3] pressed

BaseCalc.PushAddition; //Key [+] pressed

BaseCalc.PushToScreen('7'); //Key [7] pressed
BaseCalc.PushToScreen('4'); //Key [4] pressed

BaseCalc.PushSubtraction; //Key [-] pressed

BaseCalc.PushToScreen('9'); //Key [9] pressed
BaseCalc.PushToScreen('0'); //Key [0] pressed

BaseCalc.PushResultToScreen; //Key [enter] or [=] pressed
PnlScreen.Caption := BaseCalc.Screen; //Refresh the screen

Flags

TBaseCalc comes with a few flags that you can use to improve the UI

BaseCalc.ConstantOn; //True when a constant operation is set
BaseCalc.ErrorOn; //True when a error occurs

//Operations come in the TOperations type
case BaseCalc.Operation of
    opAddition: //Do something
    opSubtraction: //Do something
    opMultiplication: //Do something
    opDivision: //Do something
    opUnset: //Do something
end;

Cleaning

//To clear the display (Usually the C button)
BaseCalc.Clear;
PnlScreen.Caption := BaseCalc.Screen;

//To clear the current operation (Usually the AC button)
BaseCalc.ClearAll;
PnlScreen.Caption := BaseCalc.Screen;

Errors

EInvalidInput

Raised when a invalid character is pushed to the screen.

EOverflow

Raised when the resulting number exceeds the number of digits specified at the creation of the object. Read BaseCalc.Screen to see an approximate result and use the clear function to continue the operation. You can also use the ClearAll function to reset the calculator.

EInvalidOperation

Raised when an error occurs when performing an operation. Eg: Division by zero.