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logb, logbf, logbl, _logb, _logbf

Extracts the exponent value of a floating-point argument.

double logb(
   double x 
);
float logb(
   float x 
); // C++ only
long double logb(
   long double x 
); // C++ only 
float logbf(
   float x 
);
long double logbl(
   long double x 
);
double _logb(
   double x 
);
float _logbf(
   float x 
);

x

A floating-point value.

logb returns the unbiased exponent value of x as a signed integer represented as a floating-point value.

The logb functions extract the exponential value of the floating-point argument x, as though x were represented with infinite range. If the argument x is denormalized, it is treated as if it were normalized.

Because C++ allows overloading, you can call overloads of logb that take and return float or long double values. In a C program, logb always takes and returns a double.

Input

SEH exception

Matherr exception

± QNAN,IND

None

_DOMAIN

± 0

ZERODIVIDE

_SING

Routine

Required header

_logb

<float.h>

logb, logbf, logbl, _logbf

<math.h>

For more compatibility information, see Compatibility.

Libraries

All versions of the C run-time libraries.

Not applicable. To call the standard C function, use PInvoke. For more information, see Platform Invoke Examples.

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