C Tutorial/math.h/log2
log2
Item Value Header file math.h Declaration float log2f(float num);double log2(double num);long double log2l(long double num); Return returns the base 2 logarithm for num.
<source lang="cpp">#include <math.h>
#include <stdio.h> int main(void) { double val = 1.0; do { printf("%f %f\n", val, log2(val)); val++; } while (val<11.0); return 0; }</source>