GNU/Linux man pages
Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :
GNU/Linux |
CentOS 4.8 |
i386 |
 |
isfinite(3) |
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fpclassify, isfinite, isnormal, isnan − floating-point classification macros
#include <math.h>
int fpclassify(x);
int isfinite(x);
int isnormal(x);
int isnan(x);
int isinf(x);
Floating point numbers can have special values, such as infinite or NaN. With the macro fpclassify(x) you can find out what type x is. The macro takes any floating-point expression as argument. The result takes one of the following values:
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FP_NAN |
x is "Not a Number". |
FP_INFINITE
x is either plus or minus infinity.
FP_ZERO
x is zero.
FP_SUBNORMAL
x is too small to be represented in normalized format.
FP_NORMAL
if nothing of the above is correct that it must be a normal floating-point number.
The other
macros provide a short answer to some standard questions.
isfinite(x)
(fpclassify(x) != FP_NAN && fpclassify(x) != FP_INFINITE)
isnormal(x)
(fpclassify(x) == FP_NORMAL)
isnan(x)
(fpclassify(x) == FP_NAN)
isinf(x)
(fpclassify(x) == FP_INFINITE)
C99
isgreater(3), isinf(3)
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isfinite(3) | |