What is the log() function in C++?

Overview

In C++, the log() function is used to return the natural logarithm of the argument x that is passed to it.

Mathematically, the natural logarithm of a number is given by:

Log(x) = Log Log10Log_{10}x

Syntax

double log (double x);
float log (float x);
long double log (long double x);

Parameter value

The log() function takes a single parameter value x, which represents the number whose natural logarithm is to be computed. This parameter value must be between zero (0) and infinity(∞).

Any value passed to the function that is less than zero (0) will return NaN.

Return value

The log() function returns the natural logarithm of the argument x that is passed to it.

Code example

#include <iostream>
#include <cmath>
using namespace std;
int main ()
{
  // creating variables
  int x = 100;
	double result;
  
  // implementing the log() function
	result = log (x);
	cout << "log(100) = " << result << endl;
	
	return 0;
}

Code explanation

  • Lines 8–9: We create the variables x and result.
  • Line 12: We implement the log() function on the value of the x variable and assign the output to the result variable.
  • Line 13: We print the result variable.

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