C library function log() usage and example

C Standard Library <math.h>

double log(double x) returns the natural logarithm of x (base e logarithm).

C log() function prototype

double log(double arg);

The log() function takes a single parameter and returns the value of type float.

It is in<math.h>Defined in the header file.

To find the natural logarithm of long double or float, the following prototype can be used.

long double logl(long double arg);
float logf(float arg);

C log() parameter

Example: Usage of C log() function

#include <stdio.h>
#include <math.h>
int　main()
{
　　　　double　num　=　5.6,　result;
　　　　result　=　log(num);
　　　　printf("log(%.1f)　=　%.2f",　num,　result);
　　　　return　0;
}

Output Result

log(5.6)　=　1.72

C Standard Library <math.h>