**Introduction to the Pascal Programming Language**

**© 1998 by Dr. Thomas W. MacFarland -- All Rights Reserved**

Instructions: Review the following program and see if you can predict the outcome by completing a "pencil trace" of the code. Program output is provided at the end of this page. Compiler: The program was prepared using Standard Pascal on a UNIX-based host computer.

```
% cat PASCAL/intro_pencil-07.p
{ Introduction to the Pascal Programming Language
Dr. Thomas W. MacFarland
intro_pencil-07.p
}
{ The purpose of this program is to:
1. Demonstrate the use of integer variables and how these
variables can appear when printed using simple format
operations.
2. Demonstrate addition and subtraction with integers.
3. Demonstrate multiplication and division with integers.
4. Demonstrate the mod and div operators with integers.
5. Call attention to the need for extreme care when
determining the value of an algorithm as variables
change values during the operation of the program.
}
program Demonstrate_Integer_Math;
var A,B,C,D : integer;
E : real;
begin
A := 1;
B := A + 2;
C := A + B;
D := 2 * C;
E := D / C;
write(' A = ',A:4); write(' B = ',B:4); write(' C = ',C:4);
write(' D = ',D:4); write(' E = ',E:4:2); writeln;
D := C div B;
E := D / C;
write(' A = ',A:4); write(' B = ',B:4); write(' C = ',C:4);
write(' D = ',D:4); write(' E = ',E:4:2); writeln;
D := C mod B;
E := D / C;
write(' A = ',A:4); write(' B = ',B:4); write(' C = ',C:4);
write(' D = ',D:4); write(' E = ',E:4:2); writeln;
D := (A * B) div (D + C);
E := D / C;
write(' A = ',A:4); write(' B = ',B:4); write(' C = ',C:4);
write(' D = ',D:4); write(' E = ',E:4:2); writeln;
end. { intro_pencil-07.p }
% pc PASCAL/intro_pencil-07.p
% a.out
A = 1 B = 3 C = 4 D = 8 E = 2.00
A = 1 B = 3 C = 4 D = 1 E = 0.25
A = 1 B = 3 C = 4 D = 1 E = 0.25
A = 1 B = 3 C = 4 D = 0 E = 0.00
```