返回浮点的绝对值。
AME
fabs -- floating-point absolute value function
SYNOPSIS
#include
double
fabs(double x);
long double
fabsl(long double x);
float
fabsf(float x);
DESCRIPTION
The fabs() functions compute the absolute value of a floating-point number x.
SPECIAL VALUES
fabs(+-_) returns 0.
fabs(+-infinity) returns +infinity.
SEE ALSO
abs(3), ceil(3), floor(3), rint(3), math(3)
STANDARDS
The fabs() functions conform to ISO/IEC 9899:1999(E).
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