Object-oriented Software in Ada 95

Introduction to programming 5
• The programmer does not accidentally store a value into a memory location C0st when they
meant Cost. The programmer accidentally typed zero (0) when they meant the letter (o).
The sequence of steps written in pseudo English is transformed into the following individual Ada 95
statements which, when obeyed by a computer, will display the cost of 5.2 kilograms of apples at £1.20 a
kilogram.
Step Line Ada 95 statements
1
2
3
4
1
2
3
4
5
6
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8
Price_per_kilo : Float;
Kilos_of_apples : Float;
Cost : Float;
Price_per_kilo := 1.20;
Kilos_of_apples := 5.2;
Cost:= Price_per_kilo*Kilos_of_apples;
Put( Cost );
New_Line;
Note:
Words in bold type are reserved words in the Ada 95 language and cannot be used for the name of a
memory location.
The name of the memory location contains the character _ to make the name more readable. Spaces in
the name of a memory location are not allowed.
Each Ada 95 statement is terminated with a ;.
Multiplication is written as *.
The individual lines of code of the Ada 95 program are responsible for the following actions:
Line
1
2—3
4
5
6
7
8
Description
Allocates a memory location called Price_per_kilo that is used to
store the price per kilogram of apples. This memory location is of type
Float and can hold any number that has decimal places.
Allocates memory locations: Kilos_of_apples and Cost.
Sets the contents of the memory location Price_per_kilo to 1.20. The
:= can be read as 'is assigned the value'.
Assign 5.2 to memory location Kilos_of_apples.
Sets the contents of the memory location Cost to the contents of the
memory location Price_per_kilo multiplied by the contents of the
memory location Kilos_of_apples.
Writes the contents of the memory location Cost onto the computer
screen.
Starts a new line on the computer screen.
This solution is very similar to the solution using the pocket calculator, except that individually named
memory locations are used to hold the stored values, and the calculation is expressed in a more human readable
form.
© M A Smith - May not be reproduced without permission