log10

    double log10(double);

base-10 logarithm of a number

compile in linux with: gcc log10.c -o log10 -lm -Wall

#include <stdio.h> /* including standard library */
//#include <windows.h> /* uncomment this for Windows */
 
#include <math.h> /* including math library */
 
int main ( void ) 
{
double x;
x = log10(42000);
printf("The log10 of 42000 is %f\n",x);
return 0;
}

 output:
 user@host:~$  ./log10 
 The log10 of 42000 is 4.623249