Typos, invalid characters in book

Marsal · July 3rd, 2013, 03:27 AM

Code:

 
namespace IPAddress
{
    public class IPAddress
    {
        private int[] ip; shouldn't it be instantiated? 
                                      for example: private int[] ip = new int[32]; (?)                                                                                                         
        
        public int this[int index]
        {
            get { return ip[index]; }
            set 
            { 
                if (value == 0 || value == 1)
                ip[index] = value;

                else
                    throw new Exception("Invalid value");
            }

         }
    }

    class Program
    {
        static void Main(string[] args)
        {
            IPAddress myIP = new IPAddress();

            // initialize the IP address to all zeros
            for (int i = 0; i < 32; i++)
            {
                myIP[i] = 0
             }
        }
   }

cocis48 · July 3rd, 2013, 11:56 AM

Marsal,

I think either way will create an array of 32 items.

declaration like this : int[] ip = new int[5]; that give you a array [0,1,2,3,4] each one with a zero value.

if you use this; private int[] ip = new int[32]; the array will have 32 items all initialized to zero and you would not need the Main logic.

but this logic will also initialize to 32 items:
for (int i = 0; i < 32; i++)
{
myIP[i] = 0
}

Marsal · July 4th, 2013, 01:18 AM

Thanks for replying cocis48, but I ran it and got an null error on ip. But when I changed it to

Code:

private int[] ip = new int[32];

it ran. I printed it to console to confirm. I am just learning...

oleksiypavlenko · July 7th, 2013, 02:00 PM

On page 111 there is grammar error under Indexed Properties section.
This is how it is written: "Must be access using an index..."
Should be: "Must be accessed using an index..."

oleksiypavlenko · August 18th, 2013, 07:10 AM

On Figure 5-3 in my understanding "Customer" class should be actually "Student" class.

Rod Stephens · August 18th, 2013, 09:33 AM

You're right. Sorry about that.

Thanks for pointing this out!

chaser · August 22nd, 2013, 02:26 PM

I think that next clause is partly wrong "If multiple optional parameters exist and a value is specified for one, all preceding optional parameters must also be supplied values."
No need to supply value for preceding optional parameters. We can use named parameter.

Named and Optional Arguments (MSDN)

Example:

Code:

 
        // The first parameter, required, has no default value assigned 
        // to it. Therefore, it is not optional. Both optionalstr and  
        // optionalint have default values assigned to them. They are optional. 
        public void ExampleMethod(int required, string optionalstr = "default string",
            int optionalint = 10)

Code:

            // You can use a named parameter to make the previous  
            // statement work.
            anExample.ExampleMethod(3, optionalint: 4);

Oleg Kolpashchikov · August 22nd, 2013, 04:07 PM

We can use named parameters, but if we are not using them - and in this case we are not - we have to supply all preceding optional parameters and the phrase is absolutely correct.

oleksiypavlenko · September 8th, 2013, 11:55 AM

On page 209 it says "This type represents methods that take a float as a parameter and returns an integer", where as on page 208 the type is defined as follows:

private delegate float FunctionDelegate(float x);

Rod Stephens · September 8th, 2013, 12:01 PM

Sorry about that. The declaration on page 208 should have been:

private delegate int FunctionDelegate(float x);

This is listed on the book's errata page.