Ada - Subprogram determining the biggest number - ada

Question

The task is simple :
Create a subprogram of type function that receives exactly two parameters, both floats and returns the value of the number that is the greatest.
The execution should go as following:
Type in two floats: -13.12 2
-- User types in two numbers marked in bold
The greatest value was : 2.00
This is my code:
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Float_Text_IO; use Ada.Float_Text_IO;
procedure Test is
function Value(Float_1, Float_2 : in Float) return Float is
begin
if Float_1 > Float_2 then
return Float_1;
elsif Float_2 > Float_1 then
return Float_2;
end if;
end Value;
Float_1, Float_2 : Float;
begin
Put("Type in two numbers: ");
Get(Float_1);
Get(Float_2);
Put("The greatest value was: ");
if Float_1 > Float_2 then
Put(Float_1, Fore => 0, Aft => 2, Exp => 0);
elsif Float_2 > Float_1 then
Put(Float_2, Fore => 0, Aft => 2, Exp => 0);
end if;
end Test;
Although it works, I feel like I've overcomplicated it and haven't executed it well. For instance I haven't even used my subprogram Value at all in my main program, which I should do.
Any help is greatly appreciated!

Answer 1

Another approach uses a conditional expression:
function Max_Value (Float_1, Float_2 : in float) return float is
(if Float_1 > Float_2 then Float_1 else Float_2);
The conditional expression does the same thing as you were attempting while eliminating the need to return from the function in two different places.
Note that the logic simply returns Float_1 if it is greater than Float_2, otherwise it returns Float_2. Obviously, returning Float_2 when the two values are equal is a valid consequence of this logic.

Answer 2

Perhaps a better name for Value is Max_Value. The conditional within it is also not exhaustive. If the two numbers are equal, there is no return value. This can be corrected by using >= instead of >, at which point the only other option is that Float_2 is greater.
function Max_Value(Float_1, Float_2 : in Float) return Float is
begin
if Float_1 >= Float_2 then
return Float_1;
else
return Float_2;
end if;
end Max_Value;
Alternatively, as suggested by others, the attribute 'Max on Float can accomplish this much more concisely.
function Max_Value(Float_1, Float_2 : in Float) return Float is
begin
return Float'Max(Float_1, Float_2);
end Max_Value;
Or even more concisely:
function Max_Value(Float_1, Float_2 : in Float) return Float renames Float'Max;
Having the ability to pick the larger of two Floats using Max_Value there's now no need to have a conditional later on.
Put(Max_Value(Float_1, Float_2), Fore => 0, Aft => 2, Exp => 0);

Answer 3

As others have mentioned, Ada already provides this functionality. Thus, the most concise implementation would be
with Ada.Text_IO; use Ada.Text_IO;
with Ada.Float_Text_IO; use Ada.Float_Text_IO;
procedure Test is
function Max_Value (Left, Right : Float) return Float renames Float'Max;
begin
Put ("Type in two numbers: ");
Get (Float_1);
Get (Float_2);
Put ("The greatest value was: ");
Put (Max_Value (Float_1, Float_2));
end Test;
What you do here is declare a function Max_Value that renames the existing Float'Max function. Other answers have shown you how to implement the logic yourself.