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 kaz2100 01-22-2011 05:42 AM

sort -n, huge number

Hya,

Question
With 'sort -n': How huge can numbers be?

So far, I did
1. Check man page (info page as well) -> Not quite informative. (locale may be important.)
2. Experiment
Code:

```>cat testsort 1 11111 11111111111111 111111111111111111111 1111111111111111111111111111111111111111111111 11111111111111111111111111111111111111111111111111 11111111111111111111111111111111111111111111111110 0.1 0.000000000000000000001 000.1 100.001 100.1 1.0 1.0001 1 1.00000000000000000000000000000000000000000000000000000000000000000000000000 1.00 > cat testsort | sort -n 0.000000000000000000001 000.1 0.1 1 1 1.0 1.00 1.00000000000000000000000000000000000000000000000000000000000000000000000000 1.0001 100.001 100.1 11111 11111111111111 111111111111111111111 1111111111111111111111111111111111111111111111 11111111111111111111111111111111111111111111111110 11111111111111111111111111111111111111111111111111 >```
It looks good, except for (unnecessary) leading and trailing zero.

Happy Penguins!

 Nominal Animal 01-22-2011 09:53 AM

The general_numcompare() function in sort from coreutils-8.9 converts the numbers to the native long double type using the standard strtold() library function. This is used when the -g option is used.

Option -n uses strnumcmp() defined in coreutils-8.9/lib/strnumcmp-in.h, which does not do any numerical conversions. It is purely string-based, and should be able to compare any decimal number strings that fit into memory.

I sincirely hope this was not homework,
Nominal Animal

 gnashley 01-22-2011 10:17 AM

I'd guess they would be limited by something like MAX_LINE -probably at least 1024 chars long -or by how much RAM you have for storing it all. You could do without the 'cat' command for faster results:
Code:

`sort -n testsort`

 Nominal Animal 01-22-2011 11:28 AM

@gnashley: Some sort implementations may have line length limits, but not GNU sort from the coreutils package. From info sort:
Quote:
 GNU `sort' (as specified for all GNU utilities) has no limit on input line length or restrictions on bytes allowed within lines. In addition, if the final byte of an input file is not a newline, GNU `sort' silently supplies one. A line's trailing newline is not part of the line for comparison purposes.
So yes, the limit seems to be the available memory (RAM + swap, or resource limits, whichever are smaller).
Nominal Animal

 kaz2100 01-23-2011 06:12 AM

Hya

thanks!

My bad! I did not think of checking the source code.

This is not my homework, it is rather my job (second job). Now I feel good.

The other day, I hit the size limit of long long int in C. Of course, it did not happen in test run, and it took several days to debug. I won't run into similar problem.

Happy Penguins!

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