#include <stdio.h>
#include <math.h>
 
// Function: getDigitFromNum returns a digit at a given index of a integer.
// Goes from right to left with the starting index of 0.
int getDigitFromNum( int num, int digit ){
    num /= pow( 10, digit );
    return num % 10;
}
// Function: getDigitFromDec returns a digit at a given index of a double.
// Goes from left to right with the starting index of 0.
int getDigitFromDec( double dec, int digit ){
    dec *= pow( 10, digit );
    return (int)dec % 10;
}
// Function: getDigitFromNum returns the decimal values of a double.
double getDecimals( double dec ){
    return dec - (int)dec;
}

// Programmed by Larry Battle, bateru.com/news
// Date: April 26, 2011
// Purpose: To demonstrate how to get a digit by a position index.
#include <stdio.h>
#include <math.h>
 
int getDigitFromNum( int num, int digit ){
    num /= pow( 10, digit );
    return num % 10;
}
int getDigitFromDec( double dec, int digit ){
    dec *= pow( 10, digit );
    return ((int)dec) % 10;
}
double getDecimals( double dec ){
    return dec - (int)dec;
}
 
void main(){
    double dec = 1234.56789;
    printf( "\n%d", getDigitFromNum( (int)dec, 0 ));
    printf( "\n%d", getDigitFromDec( dec, 2 ));
    printf( "\n%f", getDecimals( dec ));
}

4
6
0.567890