C语言，c++的问题，谢谢大家

int fun(char str[])
{
	int count=0;
	for(int i=0;str[i]!='\0';i++)
	{
		if((str[i]>='a' && str[i]<='z') || (str[i]>='A' && str[i]<='Z'))
			count++;
	}
	return count;
}

int fun(char *s)
{
/*******************BEGIN*********************/
    int sum = 0;
    char *p = s;
    do 
    {
        if (*p >= 'a' && *p <= 'z')
        {
            sum++;
        }
        else if (*p >= 'A' && *p <= 'Z')
        {
            sum++;
        }
    } while (*p++ != '\0');

    return sum;
/**********************END******************/
}