The frexp Function in C & C++

More functions from the  <math.h> or <cmath> header files. Today it’s about the frexp function.

Given a floating point value a, the function returns S and n such that a = S x 2ⁿ.

The value of S is limited to a range of greater than or equal to 0.5 and less than 1.

The value of n is an integer and is returned by way of a pointer.

From C11 standard.

Test Code.

I tested the functions in Visual C++ 2010 as an console application.

// The standard library includes the system function.

#include <cstdlib>

// C++ standard I/O library.

#include <cstdio>

// C++ math library.

#include <cmath>

int main()

{

     // Header.

     printf("The frexp Function in C & C++\n\n");

     printf("Given a, the function returns S and n\n");

     printf("such that a  = S x 2 to the nth power.\n\n");

     // Counter for loop.

     int i;

     // Return value, significant.

     double S;

     // Arugment.

     double a;

     // 2 to the Nth power.

     int n = 0;

     printf("a     =   S   x 2 ^ n\n\n");

     for (i = 10; i < 27; ++i)

     {

           a = i / 10.0;

           S = frexp(a, &n);

           printf ("%4.3f = %4.3f x 2 ^ %d\n", a, S, n);

     }

     // Keep console window open.

     system("pause");

     // Return some value.

     return 0;

} // end main

 

Output.