double modf(double x, double *iptr);
float modff(floatvalue, float *iptr);
long double modfl(long doublevalue, long double *iptr);
These functions shall break the argument x into integral and
fractional parts, each of which has the same sign as the
argument. It stores the integral part as a double (for the modf()
function), a float (for the modff()
function), or a long double (for the modfl() function),
in the object pointed to by iptr.
Upon successful completion, these functions shall return the signed
fractional part of x.
x is NaN, a NaN shall be returned, and *iptr shall be
set to a NaN.
If x is ±Inf, ±0 shall be returned, and *iptr shall
be set to ±Inf.
No errors are defined.
The following sections are informative.
The modf() function computes the function result and *iptr
a = modf(x, iptr) ;
x == a+*iptr ;
allowing for the usual floating-point inaccuracies.
frexp() , isnan() , ldexp() ,
the Base Definitions volume of IEEE Std 1003.1-2001, <math.h>
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at