Arrays¶
Constrained Array¶
In this exercise, you'll work with constrained arrays. In this case, your
array type will be limited to 10 elements of Integer type. These are
your goals:
- Declare the range type
My_Indexfor the 10 elements of the array. - Declare the array type
My_Arrayusing theMy_Indextype. - Declare and implement an
Initfunction that returns an array where each element is initialize with the corresponding index. - Declare and implement a
Doubleprocedure that doubles the value of each element of an array. - Declare and implement a function called
First_Elemthat returns the first element of the array. - Declare and implement a function called
Last_Elemthat returns the last element of the array. - Declare and implement a
Lengthfunction, which returns the length of the array. - Finally, declare an object
AofMy_Arraytype and initialized it with the values 1 and 2 for the first two elements, and 42 for all other elements.
Colors: Lookup-Table¶
This exercise is based on the HTML colors exercise from a previous lab
(Records). In that exercise, one of the goals was to write the
function To_RGB to convert from the HTML_Color type to the
RGB type. These were the values for the colors:
Color Value Salmon `#FA8072`Firebrick `#B22222`Red `#FF0000`Darkred `#8B0000`Lime `#00FF00`Forestgreen `#228B22`Green `#008000`Darkgreen `#006400`Blue `#0000FF`Mediumblue `#0000CD`Darkblue `#00008B`
You probably used a case statement to implement the To_RGB
function in that exercise. Now, in this exercise, you'll rewrite the
function using a look-up table, which is implemented as an array of
constant values. In order to do that, you will:
- Declare the array type
HTML_Color_RGBfor the table. - Declare the actual table as an object of
HTML_Color_RGBtype and initialize it.
Unconstrained Array¶
In this exercise, you'll work with unconstrained arrays of Integer
type. Your goals are:
- Declare an unconstrained array type of Integer called
My_Arrayusing aPositiverange. - Declare and implement a procedure
Initwhere each element is initialized with the index starting with the last one. For example, for an array of 3 elements, the values of these elements after a call toInitare(3, 2, 1).- Hint: For an array
A, you can retrieve the index of the last element with the attribute'Last. For example:Y : Positive := A'Last;
- Hint: For an array
- Declare and implement an
Initfunction that returns an array based on the lengthLprovided to theInitfunction. This is the declaration:function Init (L : Positive) return My_Array;. Also, you must initialize the elements of the array in the same manner as for theInitprocedure described above.- Hint: The easiest way to implement this function is by simply calling
the
Initprocedure to initialize the elements. By doing this, you avoid code duplication.
- Hint: The easiest way to implement this function is by simply calling
the
- Declare and implement a
Doubleprocedure that doubles each element of an array. - Declare and implement the
Diff_Prev_Elemfunction, which returns — for each element of an input arrayA— an array with the difference between an element of arrayAand the previous element. In this case, the difference is zero for the first element.- For example:
- INPUT:
(2, 5, 15) - RETURN of
Diff_Prev_Elem:(0, 3, 10), where0: constant difference for first element;3 = 5 - 2: difference between the second and the first elements of the input array;10 = 15 - 5: difference between the third and the second elements of the input array.
- INPUT:
- For example:
Just as a hint: you can use the range attribute (A'Range) to
retrieve the range of an array A. You can also use this attribute
in the declaration of another array (e.g.: B : My_Array (A'Range)).
Alternatively, you can use the A'First and A'Last
attributes.
Quantities And Amounts¶
In this exercise, you'll create a system to keep track of quantities and
prices of products. In this system, the quantity of an individual product
is represented by the Quantity subtype and the price (or amount)
by the Amount subtype. You'll declare the array types
Quantities and Amounts to deal with information for various
products. In addition, you'll implement the following subprograms:
procedure Total: given an input array of quantities and an input array of amounts for each product, it outputs an array with the total amount for each product using theAmountstype. The total amount for an individual product is calculated by multiplying the quantity for this product by its price.function Total: it has the same purpose as the procedure we've just mentioned. The difference is that the function returns an array ofAmountstype instead of providing this array as an output parameter.function Total: given an array of quantities and an array of amounts for each product, it returns a single value ofAmounttype corresponding to the total amount for all products in the system. In other words, this function returns the sum of all total amounts for the individual products.
Hint: you can use Amount (Q) to convert from an element Q of
Quantity type to the Amount type. As you might remember, Ada
requires an explicit conversion in calculations where variables of both
integer and floating-point types are used. In our case, the Quantity
subtype is based on the Integer type and the Amount subtype
is based on the Float type, so a conversion is necessary in
calculations using those types.
String_10¶
As you know, the String type is an unconstrained array. In this
exercise, you'll deal with the String type and a custom
constrained string type called String_10. Your goals are:
- Declare the constrained string type
String_10as an array of ten characters.- Hint: declaring
String_10as a subtype ofStringis the easiest way. You may declare it as a new type as well. However, this requires some adaptations for theMaintest procedure.
- Hint: declaring
- Implement the
To_String_10function to create constrained strings ofString_10type based on an input parameter ofStringtype.
List of Names¶
In this exercise, you'll create a system that consists of a list of names
and ages. In this system, each person is represented by the Person
type, which is a record containing the name and the age of that person.
Your goals are:
Declare the
People_Arrayarray type as an unconstrained array of positive range.Complete the declaration of the
Peoplerecord type with thePeople_Aelement ofPeople_Arraytype. This array must be constrained to 10 elements using theMax_Peopleconstant.Implement the procedure
Addto add a person to the list. By default, the age of this person is set to zero in this procedure.- Hint: You may use an index to indicate the last valid position in the
array. See
Last_Validin the code below.
- Hint: You may use an index to indicate the last valid position in the
array. See
Implement the procedure
Resetto reset the list.Implement the function
Getto retrieve the age of a person from the list.Implement the procedure
Updateto update the age of a person from the list.Implement the procedure
Displayto show the complete list by using the following format:The first line must be
LIST OF NAMES:followed by the name and age of each person in the next lines.For each person on the list, the procedure must diplay the information in the following format:
NAME: XXXX AGE: YY
Hint: You should use the
Trimfunction from theAda.Strings.Fixedpackage to format the person's name. For example:Trim (P.Name, Right).
These are other hints that could be useful:
- You may need the
Integer'Min (A, B)and theInteger'Max (A, B)functions to get the minimum and maximum values in a comparison between two integer valuesAandB. - Fixed-length strings can be initialized with whitespaces using
the
otherssyntax. For example:S : String_10 := (others => ' '); - You may implement additional subprograms to deal with other types declared
in the
Names_Agespackage below, such as theName_Typeand thePersontype. For example, a functionTo_Name_Typeto convert fromStringtoName_Typemight be useful. Take a moment to reflect on which other subprograms could be useful as well.