#include 
#include 
#include 
int main()
{
    char hex[17];                        // declaration of character array.
    long long decimal, place;
    int i = 0, val, len;                  // variables declaration
    decimal = 0;
   /* Input hexadecimal number from user */
    printf("Enter any hexadecimal number: ");
    gets(hex);
/* Find the length of total number of hex digit */
    len = strlen(hex);
    len--;

    /*
     * Iterate over each hex digit
     */
    while(hex[i]!='\0')
    {
 
        /* To find the decimal representation of hex[i] */
        if(hex[i]>='0' && hex[i]<='9')
        {
            val = hex[i] - 48;
        }
        else if(hex[i]>='a' && hex[i]<='f')
        {
            val = hex[i] - 97 + 10;
        }
        else if(hex[i]>='A' && hex[i]<='F')
        {
            val = hex[i] - 65 + 10;
        }

        decimal += val * pow(16, len);