intro-to-ada

Introduction to Ada Tutorial ↩

Directory intro-to-ada\ contains Ada code examples coming from AdaCore's online tutorial Introduction to Ada.

Code examples presented in this document can be built in two ways :

• the batch file build.bat calls the GNATmake build tool (try option -help to display other features)
• the GPR tools – e.g. gprclean and gprbuild – get their build information from the project file main.gpr ¹.

forward_declaration Example

Code example forward_declaration consists of

• the source file mutually_recursive_subprograms.adb
• the project file build.gpr and
• the batch file build.bat.

We can build/execute this project as follows :

> build clean run

Book Example ▴

Code example Book consists of

• the five source files book.ads, book.adb, book-additional_operations.ads, book-additional_operations.adb and main.adb.
• the project file build.gpr and
• the batch file build.bat.

> build clean run
Book Title: Visible for my children
Book Author: Author not visible for my children
 
> gprclean -q & gprbuild -q & target\Book.exe
Book Title: Visible for my children
Book Author: Author not visible for my children

Week Example

Code example Week consists of

• the two source files Week.ads and Main.adb,
• the project file build.gpr and
• the batch file build.bat.

We can build/execute this project as follows :

> build clean run
First day of the week is Monday
 
> gprclean -q & gprbuild -q & target\Week.exe
First day of the week is Monday

🔎 Use option -verbose to display progress information :

> build -verbose clean run
Delete directory "target"
Compile 2 Ada source files to object directory "target\obj"
Execute program "Week.exe"
First day of the week is Monday

and use option -debug to see further build details such as the arguments passed to the executed commands.

Enumeration Example ▴

Code example Enumeration consists of

• the source file enumeration_example.adb,
• the project file build.gpr and
• the batch file build.bat.

Greet Example

We can build/execute this code example as follows (source file Greet.adb, project file build.gpr) :

> build -verbose run
Compile 1 Ada source files to object directory "target\obj"
Execute program "Greet.exe"
 2 3 5 7 11
 
> gprbuild & target\Greet.exe
using project file main.gpr
Compile
   [Ada]          greet.adb
greet.adb:11:04: warning: "Arr" is not modified, could be declared constant [-gnatwk]
Bind
   [gprbind]      greet.bexch
   [Ada]          greet.ali
Link
   [link]         greet.adb
 2 3 5 7 11

Footnotes ▴

[1] GNAT Project Files ↩

TODO: Executable file names.

Some project file examples :

• AdaCore/gprbuild project: gprbuild.gpr

[2] GNAT Warnings ↩

With all GNAT warnings activated, it becomes even harder to ignore the result of a function, because unused variables will be flagged. We then have two solutions to silence this warning:

• Either we annotate the variable with pragma Unreferenced, e.g.:

  B : Boolean := Read_Int (Stream, My_Int);
  pragma Unreferenced (B);
  

• Or we give the variable a name that contains any of the strings discard, dummy, ignore, junk or unused (case insensitive).

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mics/May 2024 ▲