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gusthoff merged 3 commits into from
Feb 10, 2026
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Editorial changes: minor improvements to section on decimal types #1311

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Editorial changes: minor improvement to code examples
gusthoff Feb 10, 2026
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Minor editorial change
gusthoff Feb 10, 2026
9e52385
Minor editorial change: rename procedure
gusthoff Feb 10, 2026
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53 changes: 29 additions & 24 deletions content/courses/advanced-ada/parts/data_types/numerics.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -4006,11 +4006,11 @@ precision.
In the example below, we declare two data types: :ada:`T3_D3` and :ada:`T6_D3`.
For both types, the *delta* is the same: 0.001.

.. code:: ada run_button project=Courses.Advanced_Ada.Decimal_Fixed_Point_Types.Decimal_Fixed_Point_Types
.. code:: ada run_button project=Courses.Advanced_Ada.Decimal_Fixed_Point_Types.Decimal_Precision

with Ada.Text_IO; use Ada.Text_IO;

procedure Decimal_Fixed_Point_Types is
procedure Show_Decimal_Precision is
type T3_D3 is delta 10.0 ** (-3) digits 3;
type T6_D3 is delta 10.0 ** (-3) digits 6;
begin
Expand All @@ -4028,7 +4028,7 @@ For both types, the *delta* is the same: 0.001.
& T6_D3'Image (T6_D3'First));
Put_Line ("The maximum value of T6_D3 is "
& T6_D3'Image (T6_D3'Last));
end Decimal_Fixed_Point_Types;
end Show_Decimal_Precision;

When running the application, we confirm that the delta value of both
types is indeed the same: 0.001. However, because :ada:`T3_D3` is restricted
Expand Down Expand Up @@ -4277,7 +4277,7 @@ contrast, for decimal fixed-point types, each digit increases the type's size.
Note, however, that the *delta* of the decimal type doesn't have an influence
on the type's size. For example:

.. code:: ada run_button project=Courses.Advanced_Ada.Data_Types.Numerics.Decimal_Fixed_Point_Types.Decimal_Fixed_Point_Decimal_Precision
.. code:: ada run_button project=Courses.Advanced_Ada.Data_Types.Numerics.Decimal_Fixed_Point_Types.Decimal_Fixed_Point_Size

package Decimal_Types is

Expand Down Expand Up @@ -4364,7 +4364,7 @@ on the type's size. For example:

with Decimal_Types; use Decimal_Types;

procedure Show_Decimal_Digits is
procedure Show_Decimal_Digits_Size is
begin
Put_Line ("Decimal_1_Digits'Size :"
& Decimal_1_Digits'Size'Image
Expand Down Expand Up @@ -4480,7 +4480,7 @@ on the type's size. For example:
Put_Line ("Decimal_38_Digits'Size :"
& Decimal_38_Digits'Size'Image
& " bits");
end Show_Decimal_Digits;
end Show_Decimal_Digits_Size;

When running the application above, we see that the number of bits increases
for each digit that we *add* to our decimal type declaration. On a typical
Expand Down Expand Up @@ -4517,13 +4517,13 @@ desktop PC, we may see the following results:
When we look at the base type of these decimal fixed-point types, we see that
the actual size on hardware is usually bigger. For example:

.. code:: ada run_button project=Courses.Advanced_Ada.Data_Types.Numerics.Decimal_Fixed_Point_Types.Decimal_Fixed_Point_Decimal_Precision
.. code:: ada run_button project=Courses.Advanced_Ada.Data_Types.Numerics.Decimal_Fixed_Point_Types.Decimal_Fixed_Point_Size

with Ada.Text_IO; use Ada.Text_IO;

with Decimal_Types; use Decimal_Types;

procedure Show_Decimal_Digits is
procedure Show_Decimal_Digits_Size is
begin
Put_Line ("Decimal_1_Digits'Base'Size :"
& Decimal_1_Digits'Base'Size'Image
Expand Down Expand Up @@ -4639,7 +4639,7 @@ the actual size on hardware is usually bigger. For example:
Put_Line ("Decimal_38_Digits'Base'Size :"
& Decimal_38_Digits'Base'Size'Image
& " bits");
end Show_Decimal_Digits;
end Show_Decimal_Digits_Size;

On a typical desktop PC, we may see the following results:

Expand Down Expand Up @@ -4696,11 +4696,11 @@ that the decimal fixed-point type is able to represent. For example, by writing
represent values with three digits ranging from -999 to 999 |mdash| this
corresponds to a range from -10\ :sup:`3` + 1 to 10\ :sup:`3` - 1. For example:

.. code:: ada run_button project=Courses.Advanced_Ada.Data_Types.Numerics.Decimal_Fixed_Point_Types.Decimal_Fixed_Point_Decimal_Precision
.. code:: ada run_button project=Courses.Advanced_Ada.Data_Types.Numerics.Decimal_Fixed_Point_Types.Decimal_Fixed_Point_Range

with Ada.Text_IO; use Ada.Text_IO;

procedure Show_Decimal_Digits is
procedure Show_Decimal_Range is

type D1 is
delta 1.0 digits 1;
Expand Down Expand Up @@ -4734,7 +4734,7 @@ corresponds to a range from -10\ :sup:`3` + 1 to 10\ :sup:`3` - 1. For example:
& D38'First'Image
& " .. "
& D38'Last'Image);
end Show_Decimal_Digits;
end Show_Decimal_Range;

In this example, we declare multiple decimal types. This is the range of each
one of them:
Expand Down Expand Up @@ -4776,11 +4776,11 @@ Custom range of decimal fixed-point types
Similar to floating-point types, we can define custom ranges for decimal
fixed-point types by using the :ada:`range` keyword. For example:

.. code:: ada run_button project=Courses.Advanced_Ada.Data_Types.Numerics.Decimal_Fixed_Point_Types.Decimal_Fixed_Point_Decimal_Precision
.. code:: ada run_button project=Courses.Advanced_Ada.Data_Types.Numerics.Decimal_Fixed_Point_Types.Decimal_Fixed_Point_Custom_Range

with Ada.Text_IO; use Ada.Text_IO;

procedure Show_Decimal_Digits is
procedure Show_Decimal_Custom_Range is

type D6 is
delta 1.0 digits 6;
Expand All @@ -4797,7 +4797,7 @@ fixed-point types by using the :ada:`range` keyword. For example:
& D6_R100'First'Image
& " .. "
& D6_R100'Last'Image);
end Show_Decimal_Digits;
end Show_Decimal_Custom_Range;

In this example, we declare the :ada:`D6` type with :ada:`digits 6`, which
has a range between -999,999.0 and 999,999.0. In addition, we declare the
Expand All @@ -4811,16 +4811,18 @@ Range of derived decimal fixed-point types
We can also derive from decimal fixed-point types and limit the range at the
same time |mdash| as we can do with floating-point types. For example:

.. code:: ada run_button project=Courses.Advanced_Ada.Data_Types.Numerics.Decimal_Fixed_Point_Types.Decimal_Fixed_Point_Decimal_Precision
.. code:: ada run_button project=Courses.Advanced_Ada.Data_Types.Numerics.Decimal_Fixed_Point_Types.Derived_Decimal_Fixed_Point_Range

with Ada.Text_IO; use Ada.Text_IO;

procedure Show_Decimal_Digits is
procedure Show_Derived_Decimal_Range is

type D6 is
delta 1.0 digits 6;

type D6_RD3 is new D6
range -999.0 .. 999.0;

type D6_R5 is new D6
range -5.0 .. 5.0;

Expand All @@ -4837,7 +4839,7 @@ same time |mdash| as we can do with floating-point types. For example:
& D6_R5'First'Image
& " .. "
& D6_R5'Last'Image);
end Show_Decimal_Digits;
end Show_Derived_Decimal_Range;

Here, :ada:`D6_RD3` and :ada:`D6_R5` types are both derived from the :ada:`D6`
type, which ranges from -999,999.0 to 999,999.0. For the derived type
Expand All @@ -4852,18 +4854,21 @@ Range of decimal fixed-point subtypes
Similarly, we can declare subtypes of decimal fixed-point types and limit the
range at the same time. For example:

.. code:: ada run_button project=Courses.Advanced_Ada.Data_Types.Numerics.Decimal_Fixed_Point_Types.Decimal_Fixed_Point_Decimal_Precision
.. code:: ada run_button project=Courses.Advanced_Ada.Data_Types.Numerics.Decimal_Fixed_Point_Types.Decimal_Fixed_Point_Subtype_Range

with Ada.Text_IO; use Ada.Text_IO;

procedure Show_Decimal_Digits is
procedure Show_Decimal_Subtype_Range is

type D6 is
delta 1.0 digits 6;

subtype D6_RD3 is D6
range -999.0 .. 999.0;

subtype D6_R5 is D6
range -5.0 .. 5.0;

begin
Put_Line ("D6'Range : "
& D6'First'Image
Expand All @@ -4877,7 +4882,7 @@ range at the same time. For example:
& D6_R5'First'Image
& " .. "
& D6_R5'Last'Image);
end Show_Decimal_Digits;
end Show_Decimal_Subtype_Range;

Now, :ada:`D6_RD3` and :ada:`D6_R5` are subtypes of the :ada:`D6` type, which
has a range between -999,999.0 to 999,999.0. For these subtypes, we use the
Expand All @@ -4892,11 +4897,11 @@ Range of the base type
Note that the range of a decimal fixed-point type might be smaller than the
range of its :ref:`base type <Adv_Ada_Base_Types>`. For example:

.. code:: ada run_button project=Courses.Advanced_Ada.Data_Types.Numerics.Decimal_Fixed_Point_Types.Decimal_Fixed_Point_Decimal_Precision
.. code:: ada run_button project=Courses.Advanced_Ada.Data_Types.Numerics.Decimal_Fixed_Point_Types.Decimal_Fixed_Point_Base_Range

with Ada.Text_IO; use Ada.Text_IO;

procedure Show_Decimal_Digits is
procedure Show_Decimal_Fixed_Point_Base_Range is

type D6 is
delta 1.0 digits 6;
Expand All @@ -4910,7 +4915,7 @@ range of its :ref:`base type <Adv_Ada_Base_Types>`. For example:
& D6'Base'First'Image
& " .. "
& D6'Base'Last'Image);
end Show_Decimal_Digits;
end Show_Decimal_Fixed_Point_Base_Range;

In this example, we see that the range of the :ada:`D6` goes from -999,999 to
999,999. The range of the base type, however, can be wider. On a desktop PC, it
Expand Down
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