std::modf

 

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Functions
Basic operations
abs(int)labsllabsimaxabs (C++11) abs(float)fabs divldivlldivimaxdiv (C++11) fmod	remainder (C++11) remquo (C++11) fma (C++11) fmax (C++11) fmin (C++11) fdim (C++11) nannanfnanl (C++11)(C++11)(C++11)
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ceil floor roundlroundllround (C++11)(C++11)(C++11)	trunc (C++11) nearbyint (C++11) rintlrintllrint (C++11)(C++11)(C++11)
Floating point manipulation functions
ldexp scalbnscalbln (C++11)(C++11) ilogb (C++11) logb (C++11)	frexp modf nextafternexttoward (C++11)(C++11) copysign (C++11)
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fpclassify (C++11) isfinite (C++11) isinf (C++11) isnan (C++11) isnormal (C++11) signbit (C++11)	isgreater (C++11) isgreaterequal (C++11) isless (C++11) islessequal (C++11) islessgreater (C++11) isunordered (C++11)
Macro constants
HUGE_VALFHUGE_VALHUGE_VALL (C++11)(C++11) INFINITY (C++11) NAN (C++11) math_errhandlingMATH_ERRNOMATH_ERREXCEPT (C++11)	FP_NORMALFP_SUBNORMALFP_ZEROFP_INFINITEFP_NAN (C++11)(C++11)(C++11)(C++11)(C++11)

 

Defined in header <cmath>
float       modf( float x, float* iptr );
double      modf( double x, double* iptr );
long double modf( long double x, long double* iptr );

Decomposes given floating point value x into integral and fractional parts, each having the same type and sign as x. The integral part (in floating-point format) is stored in the object pointed to by iptr.

Parameters

arg	-	floating point value
iptr	-	pointer to floating point value to store the integral part to

Return value

The fractional part of x with the same sign as x. The integral part is put into the value pointed to by iptr.

Example

Run this code

#include <iostream>
#include <cmath>
int main()
{
    double f = 123.45;
    double f3;
    double f2 = std::modf(f, &f3);
    std::cout << "Given the number " << f  << ", "
              << "modf() makes " << f3 << " and " << f2 << '\n';
 
    f = -3.21;
    f2 = std::modf(f, &f3);
    std::cout << "Given the number " << f  << ", "
              << "modf() makes " << f3 << " and " << f2 << '\n';
}

Output:

Given the number 123.45, modf() makes 123 and 0.45
Given the number -3.21, modf() makes -3 and -0.21

See also

trunc (C++11)	nearest integer not greater in magnitude than the given value (function)
C documentation for modf