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C++ Math log2()

The function computes the base 2 logarithm of a given number.

Suppose a number is 'x':

Syntax

float log2(float x);
double log2(double x);
long double log2(long double x);
double log2(integral x);

Note: The return_type can be float, double or long double.

Parameter

x: The value whose logarithm is to be calculated.

Return value

Parameter	Return value
x>1	Positive
x=1	Zero
1>x> 0	Negative
x= 0	-infinity
x<0	Not a Number(nan)

Example 1

Let's see the simple example when the value of x is greater than one.

#include <iostream>
#include<math.h>
using namespace std;
int main()
{
     int x=2;
     std::cout << "Value of x is : " <<x <<std::endl;
     cout<<"log2(x) = "<<log2(x);
     return 0;}

Output:

Value of x is : 2
log2(x) = 1

In this example, log2() function computes the logarithm value of base 2 when the value of x is greater than one

Example 2

Let's see the simple example when the value of x is equal to 1.

#include <iostream>
#include<math.h>
using namespace std;
int main()
{
     int x=1;
     std::cout << "Value of x is : " <<x <<std::endl;
     cout<<"log2(x) = "<<log2(x);
     return 0;
}.

Output:

Value of x is : 1
log2(x) = 0

In this example, log2() function computes the logarithm value of base 2 when the value of x is equal to one.

Example 3

Let's see the simple example when the value of x lies between 0 and 1.

#include <iostream>
#include<math.h>
using namespace std;
int main()
{
     float x=0.2;
     std::cout << "Value of x is : " <<x <<std::endl;
     cout<<"log2(x) = "<<log2(x);
     return 0;
}

Output:

Value of x is : 0.2
log2(x) = -2.32193

In this example, log2() function computes the logarithm value of base 2 when the value of x is equal to 0.2.

Example 4

Let's see the simple example when the value of x is equal to zero.

#include <iostream>
#include<math.h>
using namespace std;
int main()
{
     int x=0;
     std::cout << "Value of x is : " <<x <<std::endl;
     cout<<"log2(x) = "<<log2(x);
     return 0;
}

Output:

Value of x is : 0
log2(x) = -inf

In this example, log2() function computes the logarithm value of base 2 when the value of x is equal to 0.

Example 5

Let's see the simple example when the value of x is less than zero.

#include <iostream>
#include<math.h>
using namespace std;
int main()
{
     float x= -1.50;
     std::cout << "Value of x is : " <<x <<std::endl;
     cout<<"log2(x) = "<<log2(x);
     return 0;
}

Output: