log2 - calculate the base-2 logarithm of a number
log2, log2f, log2l - base-2 logarithmic function
#include <math.h>
double log2(double x);
#include <math.h>
double log2(double x);
float log2f(float x);
long double log2l(long double x);Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
This function calculates the base-2 logarithm of x.
These functions return the base-2 logarithm of x.
This function returns, as a double, the base-2 logarithm of x.
On success, these functions return the base-2 logarithm of
x.
For special cases, including where x is 0, 1, negative,
infinity, or NaN, see log(3).
#include <math.h>
#include <stdio.h>
int main(void)
{
printf("This is CS%i\n", (int) log2(1125899906842624));
}