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Editorial Team
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Asked: 2026-06-15T08:08:38+00:00

I am wondering how to convert an integer to a long_integer and a long_integer

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I am wondering how to convert an integer to a long_integer and a long_integer to a Positive_Count. Every way I have tried has given me and error even though the conversion should be easy in that instance.

For example, doing

long := long_integer(int1) + long_integer(int2);

will make long a negative value sometimes even though both integer were positive.

The code of the function I’m running , steps split for debugging:

--calcKey--
procedure calcKey(x: in String16; key: out External_IO.Positive_Count) is
  s1, s2 : String2;
  int1, int2 : integer;
  long1, long2 : long_integer;
begin
  s1 := x(12..13); 
  s2 := x(15..16); 
  put_line("s1: " &s1& "- s2: " &s2);
  int1 := abs StringToInt(s1);
  int2 := abs StringToInt(s2); 
  put("int1: " & Integer'image(int1) & " | int: " & Integer'Image(int2)); new_line;
  long1 := long_integer(int1); 
  long2 := long_integer(int2);
  long1 := long1 + long2; 
  put_line("long := " & long_integer'Image(long1));
  long1 := (long1 mod 256) + 1;
  key := External_IO.Positive_Count(long1); 
  put_line("Key : " & External_IO.Positive_Count'Image(key));

  new_line;
end calcKey;

calling the function:

calcKey("0123456789abcdef",k);
calcKey("0123456789abcdef",k);
calcKey("0123456789abcdef",k);
calcKey("0123456789abcdef",k);
calcKey("fedvba9876543210",k);
calcKey("fedvba9876543210",k);

The output:

s1: bc- s2: ef
int1:  2011929758 | int:  1667393125
long := -615644413
Key :  4

s1: bc- s2: ef
int1:  287586 | int:  1667393125
long :=  1667680711
Key :  200

s1: bc- s2: ef
int1:  13132642 | int:  1667393125
long :=  1680525767
Key :  200

s1: bc- s2: ef
int1:  13132642 | int:  1667393125
long :=  1680525767
Key :  200

s1: 43- s2: 10
int1:  13120308 | int:  859058225
long :=  872178533
Key :  102

s1: 43- s2: 10
int1:  6697780 | int:  859058225
long :=  865756005
Key :  102
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1 Answer

  1. Editorial Team

    (THis should be a comment, but it’s too long so I’m submitting it as an answer)

    First thing I would do is actually verify that long_int is what you think it is, i.e doing INTEGER'SIZE and LONG_INTEGER'SIZE, it could very well be that on your platform they are the very same size,

    From the Ada definition:

    Note that the ranges and sizes of these types can be different in
    every platform (except of course for Boolean and
    [[Wide_]Wide_]Character). There is an implementation requirement that
    the size of type Integer is at least 16 bits, and that of Long_Integer
    at least 32 bits (if present) RM 3.5.4 (21..22) (Annotated). So if you
    want full portability of your types, do not use types from Standard
    (except where you must, see below), rather define you own types. A
    compiler will reject any type declaration whose range it cannot
    satisfy.

    If they are the same size you could be overflowing when you add 2 really large ints, thus giving the results you see.

    Source: http://en.wikibooks.org/wiki/Ada_Programming/Libraries/Standard

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