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+---- Thread: IsNan and IsInf Functions (/showthread.php?tid=1984)
IsNan and IsInf Functions - SMcNeill - 09-10-2023
If one ever needs to determine if a calculation generates a Nan result or an INF result, they can always use the following little snippet of code:
Save as isnan.h:
Code: (Select All)
#include <stdio.h>
#include <math.h>
#include <float.h>
int IsNan (long double n);
int IsInf (long double n);
IsNan (long double n) { return -isnan(n); }
IsInf (long double n) { return -isinf(n); }And the test code to check for NaN and Inf:
Code: (Select All)
DECLARE LIBRARY "isnan"
FUNCTION IsNan% (BYVAL n AS _FLOAT)
FUNCTION IsInf% (BYVAL n AS _FLOAT)
END DECLARE
PRINT IsNan(0 / 0), IsInf(0 / 0)
PRINT IsInf(1 / 0), IsInf(1 / 0)
PRINT IsInf(0 / 1), IsInf(0 / 1)
Notice the output is:
0 / 0 is NaN but is *not* INF.
1 / 0 is NaN and is also INF.
0 / 1 is neither NaN, nor is it INF.
RE: IsNan and IsInf Functions - Dimster - 09-10-2023
Thanks for this Steve. Don't mean to highjack this thread but it also demonstrates the use of different kinds of brackets and I was wondering the correct use of them. They are (), [], and {}. The last one in particular I haven't used at all.
RE: IsNan and IsInf Functions - mnrvovrfc - 09-10-2023
Only the rounded ones, that you get pressing `SHIFT+9` and `SHIFT+0` have anything to do with this BASIC dialect.
In a few BASIC dialects and other languages, the square brackets is sometimes used like `MID$()` for one character. But not in QB64 at the moment.
Don't let yourself confounded by B.A.M., it was Charlie's choice to use other brackets there and only there.