How do I make a function to subtract and add values in a TEdit?

Question

I'm new to programming, I'm looking to make a command to add and subtract values.

Where I would have a TEdit.Value with the initial value 0 and 2 more buttons, one of " + " and one of " - ", to increase or decrease the value, but I still don't know how to do that, can someone give me one light?

I looked up some examples of how to do this, but I didn't find anything that could help me.

In Delphi you use the `+` and `-` operators for addition and subtraction, respectively. This is documented. — David Heffernan, Jan 21 '23 at 07:20
To learn the basics, you should look for a book or publication about Delphi. E.g. google for "essential delphi" by Marco Cantú. — Tom Brunberg, Jan 21 '23 at 08:28
Duplicate of [Delphi: Addition and subtraction](https://stackoverflow.com/q/8635966/4299358) and [Delphi: Arithmetic expression on Wikibooks](https://en.wikibooks.org/wiki/Delphi_Programming/Arithmetic_expression) - I wonder what "_I looked up some examples_" means to you if you haven't found these. — AmigoJack, Jan 21 '23 at 08:36

Remy Lebeau · Accepted Answer · 2023-01-21T19:34:00.850

4

You could use StrToInt() to convert the Edit's current Text string to an integer, then increment/decrement the integer, then use IntToStr() to convert the integer to a string and assign it back to the Text property. For example:

var Value: Integer := StrToInt(Edit1.Text);
Inc(Value); // or Dec()
Edit1.Text := IntToStr(Value);

However, a better option would be to use a UI control that is specifically designed to handle numeric input, such as a TSpinEdit, or a TUpDown attached to an Edit control.

edited Jan 21 '23 at 19:34

answered Jan 21 '23 at 05:02

Remy Lebeau

555,201
31
458
770

2

A TSpinEdit is not only better for handling numeric input, but as it contains the buttons already, it's job done. – Garth Thornton Jan 21 '23 at 19:08

How do I make a function to subtract and add values in a TEdit?

1 Answers1