The logb() function in C++ is used to return the logarithm of a given number (|x|) using the FLT_RADIX as the base of the logarithm.
Note:
FLT_RADIXis the value of the base of the logarithm. Generally, it is 2, so thelogb()is equivalent tolog2()for any positive number value.
The logb() function is defined in the <cmath> header file.
double logb (double x);
float logb (float x);
long double logb (long double x);
double logb (T x); // For integral type
The logb() function takes a single parameter value:
x: The number whose logarithm is computed.
The logb() function returns the logarithm of the argument passed to it as its parameter value.
#include <iostream>#include <cmath>using namespace std;int main (){double x =100, result;result = logb(x);cout << "logb(" << x << ") = " << "log(|" << x << "|) = "<< result << endl;return 0;}
x and result.logb() function on the x variable and assign the output to the other variable result.result variable.