C log2 function calculates base 2 logarithm for argument

Syntax

C log2 function has the following syntax.

• float log2f(float num);
• double log2(double num);
• long double log2l(long double num);

Header

C log2 functions are from math.h.

Description

C log2 functions return the base 2 logarithm for num.

Example

The following code calculates base 2 logarithm for argument by using C log2 functions.

#include <math.h>
#include <stdio.h>
/*  w  w  w .  ja va2 s  .  c o  m*/
int main(void)
{
  double val = 1.0;

  do {
    printf("%f %f\n", val, log2(val));
    val++;
  } while (val<11.0);

  return 0;
}

The code above generates the following result.