Performing Calculations and Math Using EditBoxes

User input with editboxes are entered as a string datatype. The computer can not perform calculate using strings. The computer needs numbers in an integer or floating point datatype to make mathematical calculations. The solution is to convert the string into a integer of floating point number, perform the calculation, then convert the calculation back to a string so it can be displayed in the editbox or label.

IntToStr() - Converts an Integer to a String

StrToInt() - Converts a String to an Integer

FloatToStr() - Converts a Floating Point to a String

StrToFloat() - Converts a String to a Floating Point

Example:

edAnswer.Text := FloatToStr(StrToFloat(edFirstNum.Text) + StrToFloat(edSecondNum.Text));

Video Tutorial: Free Pascal Tutorial 19 - String Conversions and Calculations - Lazarus (8:21)

The code for Tutorial 18, 19, 20 & 21 is found on Tutorial 21’s Page