C log() function

C log() function - Calculate natural logarithm


double log(double x)

The log() function is used to calculate the natural logarithm (base e) of x.


Name Description Required /Optional
x Value whose logarithm is to be found. Required

Return value from log()

  • Upon successful completion, the function returns the natural logarithm of x.

Example: log() function

The following example shows the usage of log() function.

#include <math.h>
#include <stdio.h> 
int main(void)
    double x = 1.0, y;
    y = log(x);
    printf("The natural logarithm of %lf is %lf\n", x, y);
	x = 10.0;
    y = log(x);
    printf("The natural logarithm of %lf is %lf\n", x, y);
   	x = 1000.0;
    y = log(x);
    printf("The natural logarithm of %lf is %lf\n", x, y);


The natural logarithm of 1.000000 is 0.000000
The natural logarithm of 10.000000 is 2.302585
The natural logarithm of 1000.000000 is 6.907755

C Programming Code Editor:

Previous C Programming: C ldexp()
Next C Programming: C log10()

Follow us on Facebook and Twitter for latest update.

C Programming: Tips of the Day

What's the point of const pointers?

const is a tool which you should use in pursuit of a very important C++ concept:

Find bugs at compile-time, rather than run-time, by getting the compiler to enforce what you mean.

Even though it does not change the functionality, adding const generates a compiler error when you're doing things you didn't mean to do. Imagine the following typo:

void foo(int* ptr)
    ptr = 0;// oops, I meant *ptr = 0

If you use int* const, this would generate a compiler error because you're changing the value to ptr. Adding restrictions via syntax is a good thing in general. Just don't take it too far -- the example you gave is a case where most people don't bother using const.

Ref : https://bit.ly/33Cdn3Q