How to write own isnumber() function?

Question

I\'m new to C and I\'m thinking how to write this function myself. I take a parameter from command line, so it is stored in argv array and I want to decide whether it is or

Answer 1

I'm not sure if you want to check if it's a number or a digit and argv[1] is of type char * not int so you should do something like that:

bool isDigit(char *param)
{   
    return (*param >= `0` && *param <= `9`)
}

bool isNumber(char *param)
{   
    while (param)
    {
        if (!isDigit(param))
            return false;
       param++;
    }
    return true;
}