As of October, 2016, Embarcadero is offering a free release
of Delphi (Delphi
10.1 Berlin Starter Edition ). There
are a few restrictions, but it is a welcome step toward making
more programmers aware of the joys of Delphi. They do say
"Offer may be withdrawn at any time", so don't delay if you want
to check it out. Please use the
link to let me know if the link stops working.
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Given four sets of numbers with four numbers in each set, write an equation
that is satisfied by each set of numbers. The numbers are labeled A,B,C,D.
Operations may include +, -, ×, and ÷. Any letter
may appear in any location in the equation. Equations will have the form (letter
operation letter) operation letter = letter, for example (A+B)×D=C,
or (D-C) ÷ A=B. Parentheses surround the first two
letters so operations can always be performed from left to right.
Background & Techniques
Notes for non-programmers:
This program is loosely based on a problem type included in the Mensa
Number Puzzles, Harold Gale, Carton Books. It generates
random problems within difficulty constraints set by the user.
The Options button can be used to modify the included init file,
EquSearch.ini, to control several variables:
|Controlling equation complexity -
|Operators: specify which of the four operators, +, -,
×, ÷, are to be used in creating equations.|
|Maximum values:- specify the largest number used in creating problems|
|Problem set size: problems are presented in sets with a reward
screen shown for sufficiently high scores in any
|Minimum score for reward - expressed as a decimal, default value is
The "reward" screen as distributed shows a default image and
plays a "Cheers.wav" audio file when displayed. If
additional .wav files are included in the same folder as the program, one
is selected randomly to accompany the reward screen. If any .jpg
image files are included in the program file, one is randomly selected to
display in the reward screen.
Non-programmers are welcome to read on, but may want to jump to bottom of
this page to download the executable program now.
Notes for programmers:
There are a number of Delphi features used here that may be new to beginning
or intermediate programmers, Here are some examples:
|I used the init file, TIniFile, component to hold the run time
options defined above.
Note on ReadBool usage: It's not very well defined, but
boolean values in an init file must be specified as 0 for false or 1 for
true (actually any non-zero value for true).
|Special characters for multiply and divide: I referred to the FontViewer
program to refresh my memory about the location of the special
characters × and ÷ and used them throughout this
program since non-programmers may not recognize * and /
as multiply and divide. |
|FindFirst & FindNext functions are used to identify Jpg
and Wav files for use in the reward dialog.|
|Component arrays: the six lists used to construct equations are put into
an array for ease of use. |
|The Controls array within each of the four panels containing the
sets of numbers is scanned to find the numbers in the Tedits
when evaluating equations. Rather than use names or tag
values to identify how the edits correspond to the A ,B. C, D labels, I
simply made sure that the edits were encountered in A, B, C, D
order. To do this, remember that controls are arranged in
the order that they are drawn, called Z-order. Since those drawn first me ay
be overlaid by those drawn later, the effect is drawing from back to
front. So right clicking a control and selecting
"Send To Back" moves the control to the top of the list
. Doing this for D, C ,B, and A in that order ensures that
they will be retrieved in the expected order (A, B, C, D). |
That brief outline that may be enough to get you started, so let's
Running/Exploring the Program
Suggestions for Further Explorations
the parentheses locations variable.
multiple solutions for most (all?) sets of numbers. How many? Does
the number depend on the operators used?
|Original: May 25, 2002
February 18, 2016