Formal parameter "Item" is not referenced - ada

Question

By using subprograms, I try to write a program that displays a VAT table. It asks the user to enter some data and based on these data, displays a VAT-table. However, I get a warning which says: "Formal parameter "Item" is not referenced". My program does display a table but it looks terrible. Here you can see how far I have come:
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
with Ada.Float_Text_IO; use Ada.Float_Text_IO;
procedure Underprogram is
V_percent, S_length, H_price, L_price, Price_Wm : Float;
X: Integer;
procedure Get_Pop(Item : out Float ) is
begin
Put_Line("Write ur first price:");
Get(H_price, width=>0);
while H_price < 0.0 loop
Put("Wrong inout, try again! : ");
Get(H_price);
end loop;
loop
Put_Line("Write in your second price:");
Get(L_price, width=>0);
if H_price > L_price then
exit; end if; end loop;
Put_Line("Which VAT percent do ypu want? ");
Get(V_percent, width=>0);
while V_percent > 100.0 or V_percent <= 0.0 loop
Put_Line("The vat percent you fed in is invalid, try again! ");
Get(V_percent);
end loop;
Put_Line("Which step length do you want? ");
Get(S_length, width=>0);
while S_length < 0.1 or S_length > 1.0 loop
Put_Line("The step length you just fed in is out of the range: ");
Get(S_length);
end loop; end Get_Pop;
procedure Put_pop(Item : in Float) is
begin
X := Integer(Float'Floor((H_price-L_price) / S_length + 1.0));
Put_Line(" === Vattabell === ");
Put_Line("Price without VAT Vat Price with VAT ");
Put_Line("--------------- ---- -------------- ");
for I in 0..X -1 loop
Price_Wm := L_price + Float(I) * S_length;
Put(Price_Wm, 5,2,0);
Put((L_price + Float(I) * S_length) * V_percent/100.0,
13,2,0);
Put(Price_Wm * (1.0 + V_percent/100.0), 15,2,0);
New_Line;
end loop;
end Put_pop;
begin
Get_Pop(V_percent); Put_pop(V_percent);
Get_Pop(S_length); Put_pop(S_length);
Get_Pop(H_price); Put_pop(H_price);
Get_Pop(L_price); Put_pop(L_price);
Get_Pop(Price_Wm); Put_pop(Price_Wm);
end Underprogram;
Here is an update: I just rewrote my code based in the comments and it works fine. Now I wonder how I can add more functions and subprograms to this code so that the Underprogram procedure looks cleaner?. Right now I have just two subprograms:
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
with Ada.Float_Text_IO; use Ada.Float_Text_IO;
procedure Underprogram is
Higher, Lower, VAT, Step, Price_without_VAT: Float;
X : Integer;
procedure Get_data(Item: out Float) is
begin
Get(Item);
end Get_data;
procedure Put_data(Item: in Float) is
begin
Put(Item, 2,2,0); Put(" ");
end Put_data;
begin
Put("Write the higher price: ");
Get_data(Higher);
while Higher < 0.0 loop
Put("Wrong input, try again: ");
Get_data(Higher); end loop;
loop
Put("Write the lower price: ");
Get_data(Lower);
if Lower < Higher then
exit; end if; end loop;
Put("Write the VAT : ");
Get_data(VAT);
while VAT > 100.0 or VAT < 0.0 loop
Put("Wrong input, try again:");
Get_data(VAT);
end loop;
loop
Put("Write the step: ");
Get_data(Step);
if Step > 0.0 then
exit; end if; end loop;
Put_data(Higher);
Put_data(Lower);
Put_data(VAT);
Put_data(Step);
X := Integer(Float'Floor((Higher-Lower) / Step + 1.0));
Put_Line(" === VATTABELL === ");
Put_Line("Price without VAT VAT Price with VAT ");
Put_Line("--------------- ---- -------------- ");
for I in 0..X -1 loop
Price_without_VAT := Higher + Float(I) * Step;
Put(Price_without_VAT, 5,2,0);
Put((Higher + Float(I) * Step) * VAT/100.0, 13,2,0);
Put(Price_without_VAT * (1.0 + VAT/100.0), 15,2,0);
New_Line;
end loop;
end Underprogram;

Answer 1

The following code is your code after re-organized by the pretty printer provided in the GNAT Studio 2020 Community Edition:
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Integer_Text_IO; use Ada.Integer_Text_IO;
with Ada.Float_Text_IO; use Ada.Float_Text_IO;
procedure Underprogram is
V_percent, S_length, H_price, L_price, Price_Wm : Float;
X : Integer;
procedure Get_Pop (Item : out Float) is
begin
Put_Line ("Write ur first price:");
Get (H_price, Width => 0);
while H_price < 0.0 loop
Put ("Wrong inout, try again! : ");
Get (H_price);
end loop;
loop
Put_Line ("Write in your second price:");
Get (L_price, Width => 0);
if H_price > L_price then
exit;
end if;
end loop;
Put_Line ("Which VAT percent do ypu want? ");
Get (V_percent, Width => 0);
while V_percent > 100.0 or V_percent <= 0.0 loop
Put_Line ("The vat percent you fed in is invalid, try again! ");
Get (V_percent);
end loop;
Put_Line ("Which step length do you want? ");
Get (S_length, Width => 0);
while S_length < 0.1 or S_length > 1.0 loop
Put_Line ("The step length you just fed in is out of the range: ");
Get (S_length);
end loop;
end Get_Pop;
procedure Put_pop (Item : in Float) is
begin
X := Integer (Float'Floor ((H_price - L_price) / S_length + 1.0));
Put_Line (" === Vattabell === ");
Put_Line ("Price without VAT Vat Price with VAT ");
Put_Line ("--------------- ---- -------------- ");
for I in 0 .. X - 1 loop
Price_Wm := L_price + Float (I) * S_length;
Put (Price_Wm, 5, 2, 0);
Put ((L_price + Float (I) * S_length) * V_percent / 100.0, 13, 2, 0);
Put (Price_Wm * (1.0 + V_percent / 100.0), 15, 2, 0);
New_Line;
end loop;
end Put_pop;
begin
Get_Pop (V_percent);
Put_pop (V_percent);
Get_Pop (S_length);
Put_pop (S_length);
Get_Pop (H_price);
Put_pop (H_price);
Get_Pop (L_price);
Put_pop (L_price);
Get_Pop (Price_Wm);
Put_pop (Price_Wm);
end Underprogram;
I simply copied the source into the GNAT Studio IDE, saved the file, then chose the Pretty Print option under the Code tab in the IDE. I did nothing to manually format the code.
See how the use of indentation helps visually identify the beginning and ending of procedures, functions, and loops.

Answer 2

The reason that the first pass through the table reports the VAT data as zero is that you pass V_Percent to Get_Pop as the actual for the out parameter Item, but you never assign to Item, with the result that the compiler assigns something to it on exit from the procedure, overwriting the value of V_Percent which you already assigned explicitly.
Get_Pop can’t logically have a single out parameter, because its job (as you’ve coded it) is to read four values. Either no parameters at all, or give each required value its own out parameter, or create a record type to hold all 4 values.