int tolower(int c)
{
if ((c >= 'A') && (c <= 'Z'))
return c + ('a' - 'A');
return c;
}
int htoi(char s[])
{
int i;
int n = 0;
if (s[0] == '0' && (s[1]=='x' || s[1]=='X'))
{
i = 2;
}
else
{
i = 0;
}
for (; (s[i] >= '0' && s[i] <= '9') || (s[i] >= 'a' && s[i] <= 'f') || (s[i] >='A' && s[i] <= 'F');++i)
{
if (tolower(s[i]) > '9')
{
n = 16 * n + (10 + tolower(s[i]) - 'a');
}
else
{
n = 16 * n + (tolower(s[i]) - '0');
}
}
return n;
}
