How to output Integers using the Put_Line method? - ada

Question

I can't get this program to compile because it doesn't seem to print integer variables along with strings in the Put_Line method. I've looked at source code online and it works when they do it so where am I going wrong. Thanks for your help.
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
procedure MultiplicationTable is
procedure Print_Multiplication_Table(Number :in Integer; Multiple :in Integer) is
Result : Integer;
begin
for Count in 1 ..Multiple
loop
Result := Number * Count;
Put_Line(Number & " x " & Count & " = " & Result);
end loop;
end Print_Multiplication_Table;
Number : Integer;
Multiple : Integer;
begin
Put("Display the multiplication of number: ");
Get(Number);
Put("Display Multiplication until number: ");
Get(Multiple);
Print_Multiplication_Table(Number,Multiple);
end MultiplicationTable;`

Answer 1

The problem is that you're using & with strings and integers.
Try one of the following:
Replace Number inside the parameter of put with Integer'Image(Number)
Or break up the Put_Line into the components that you want; ex:
-- Correction to Put_Line(Number & " x " & Count & " = " & Result);
Put( Number );
Put( " x " );
Put( Count );
Put( " = " );
Put( Result);
New_Line(1);

Answer 2

Try this:
Put_Line(Integer'Image(Number) & " x " & Integer'Image(Count) & " = " & Integer'Image(Result));

Answer 3

You're already have with and use clauses for Ada.Integer_Text_IO, but you're not actually using it.
Change this:
Put_Line(Number & " x " & Count & " = " & Result);
to this:
Put(Number); Put(" x "); Put(Count); Put(" = "); Put(Result); New_Line;
(I normally wouldn't put multiple statements on one line, but in this case it makes sense.)
Note that Integer'Image prepends non-negative integers with a space, something I've always found greatly annoying; Ada.Integer_Text_IO.Put doesn't do that (unless you ask it to).
You could define overloaded "&" functions, something like this:
function "&"(Left: String; Right: Integer) return String is
begin
return Left & Integer'Image(Right);
end "&";
function "&"(Left: Integer; Right: String) return String is
begin
return Integer'Image(Left) & Right;
end "&";
which would make your original Put_Line call valid, but the multiple Put calls are probably better style.

Answer 4

Building on the answer (and a comment in another question) from Keith Thompson, here is a full Ada program that can output strings and integers with &, using Put_Line, but without the spaces that Integer'Image would otherwise prepend:
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
procedure Main is
function lstrip(S: String) return String is
begin
if S(S'First) = ' ' then
return S(S'First+1 .. S'Last);
else
return S;
end if;
end;
function "&"(Left: String; Right: Integer) return String is
begin
return Left & lstrip(Integer'Image(Right));
end "&";
function "&"(Left: Integer; Right: String) return String is
begin
return lstrip(Integer'Image(Left)) & Right;
end "&";
begin
Put_Line("x=" & 42);
end Main;