topic Re: input function doesn't work with long strings in SAS Programming

input function doesn't work with long strings

prizzo60 — Mon, 07 Jun 2021 16:13:06 GMT

in my work I have strings that contain only digits. Very long strings up to 32 characters.
If I use the function input() to convert from character to numeric, but with strings longer than 16 characters the numeric result is visibly wrong. I include the code explaining the problem, and the printout of the results. Can anyone explain to me where am I wrong?

DATA TEST_INPUT ;
INPUT CHAR_TEXT $32. ;
DATALINES;
3659218487881310922172417
3662444754643708821993473
;

RUN ;

DATA TEST_INPUT2 ;
SET TEST_INPUT ;
FORMAT CHAR_2_NUM 32. ;
FORMAT CHAR_2_NUM_16_DIGIT 32. ;
FORMAT CHAR_2_NUM_17_DIGIT 32.;
CHAR_2_NUM = INPUT(CHAR_TEXT,32.);
CHAR_2_NUM_16_DIGIT =INPUT(SUBSTR(CHAR_TEXT,1,16),32.);
CHAR_2_NUM_17_DIGIT =INPUT(SUBSTR(CHAR_TEXT,1,17),32.);
RUN ;

NUMB_TEXT	CHAR_2_NUM	CHAR_2_NUM_16_DIGIT	CHAR_2_NUM_17_DIGIT
3659218487881310922172417	3659218487881310752735232	3659218487881310	36592184878813112
3662444754643708821993473	3662444754643709451042816	3662444754643708	36624447546437088

Re: input function doesn't work with long strings

Reeza — Mon, 07 Jun 2021 16:19:12 GMT

SAS (and many other applications including Excel) cannot store numeric values beyond 16 digits.

https://documentation.sas.com/doc/en/pgmsascdc/9.4_3.5/hostunx/p12zsdbylnn6c2n1i48z7djr6uzo.htm

Re: input function doesn't work with long strings

jimbarbour — Mon, 07 Jun 2021 16:26:08 GMT

As I recall 2 to the 52nd power (2**52) or 4,503,599,627,370,496 is the largest number the current release of SAS can contain without loss of precision. SAS is all double precision floating point binary in terms of numeric representation. It doesn't have BIGINT or DECIMAL or other formats that might handle larger numbers.

Jim

Re: input function doesn't work with long strings

ballardw — Mon, 07 Jun 2021 16:28:50 GMT

What are you measuring or counting that requires 32 significant digits?

Re: input function doesn't work with long strings

prizzo60 — Mon, 07 Jun 2021 16:57:35 GMT

I agree , it is very strange number with 32 significant digits, but this number is a "serial number" deriving from contract in stock market.

Re: input function doesn't work with long strings

FreelanceReinh — Mon, 07 Jun 2021 17:12:30 GMT

Hello @prizzo60,

To store your example 25-digit strings (or even 32-digit strings) in numeric variables without losing precision, SAS under Windows or Unix would need 81 (106) mantissa bits -- i.e., 29 (54) more than are available.

See Re: Strange behavior of long int in SAS for explanations and additional links.

I would store these "numbers" in a character variable of sufficient length (and look forward to coding the algorithms needed to perform calculations with them, if any).

Re: input function doesn't work with long strings

ballardw — Mon, 07 Jun 2021 17:13:57 GMT

@prizzo60 wrote:
I agree , it is very strange number with 32 significant digits, but this number is a "serial number" deriving from contract in stock market.

If you aren't doing arithmetic with the variable it should be character.

Any sequential behavior of a "serial number" would maintain an you won't lose any information.

Account numbers, addresses, phone numbers, part numbers: character.

Height , weight, currency values, counts or measurements with units: numeric.

Re: input function doesn't work with long strings

Reeza — Mon, 07 Jun 2021 18:06:39 GMT

Then if you're not doing math with it, you can store it as a character.
If you need specific portions for identifiers then you can parse them out into separate fields.

Re: input function doesn't work with long strings

Kurt_Bremser — Mon, 07 Jun 2021 18:19:26 GMT

@prizzo60 wrote:
I agree , it is very strange number with 32 significant digits, but this number is a "serial number" deriving from contract in stock market.

Then it will never be used in calculations, so store it as a character string. Just like we do with our policy "numbers".

Re: input function doesn't work with long strings

mkeintz — Tue, 08 Jun 2021 03:12:19 GMT

The only thing I would add to all the comments to keep this variable in character format is to make sure that the value is right-justified. I.e. any value with fewer characters should have leading blanks not trailing blanks. This will preserve a sort order identical to what would be the case if you had sufficiently precise numeric values.

Or you might insert leading zeroes to eliminate blanks.

Added note: If you don't right justify and allow trailing blanks, then sorting on these values will produce lexicographic ordering (i.e. '1111' is less than '22 '), rather than ordering by the implicit value (i.e. ' 22' is less than '1111').