GNU/Linux man pages
Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :
GNU/Linux |
CentOS 5.4 |
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isless(3) |
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isgreater, isgreaterequal, isless, islessgreater, isunordered − macros to test a relation
#include <math.h>
int isgreater(x,y);
int isgreaterequal(x,y);
int isless(x,y);
int islessequal(x,y);
int islessgreater(x,y);
int isunordered(x,y);
Compile with −std=c99; link with −lm.
The normal
relation operations (like less) will fail if one of the
operands is NaN. This will cause an exception. To avoid
this, C99 defines these macros. The macros are guaranteed to
evaluate their operands only once. The operand can be of any
real floating-point type.
isgreater()
determines (x) > (y) without an exception if x or y is NaN.
isgreaterequal()
determines (x) >= (y) without an exception if x or y is NaN.
isless()
determines (x) < (y) without an exception if x or y is NaN.
islessequal()
determines (x) <= (y) without an exception if x or y is NaN.
islessgreater()
determines (x) < (y) || (x) > (y) without an exception if x or y is NaN. This macro is not equivalent to x != y because that expression is true if x or y is NaN.
isunordered()
is true if x or y is NaN and false otherwise.
Not all hardware supports these functions, and where it doesn’t, they will be emulated by macros. This will give you a performance penalty. Don’t use these functions if NaN is of no concern for you.
C99
fpclassify(3) isnan(3)
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isless(3) | |