Refrencing Array

Hi this is my first post here and im really hoping i can get a little help on something which my be really easy anyways ....
I have never used typedef before i need to declare a typedef for a char acter array of 3 chars.

would this be correct:
typedef char value_type[3];

also i have to write a class and one of the private member variable is a array of type value_type from above. I need to write an accessor function it display the contents of the array, but you can not return arrays in c++, so would i go about return a refrence to that array??

Any help would be appreciated Thanks!

Read this about typedefs
http://www.cplusplus.com/doc/tutorial/tut3-6.html.

For your second question I believe that you could just use a loop if i am reading your question right.
eg.

Code:

#include <iostream>

class myClass
{
  public:    
    myClass()
    {
      int i;
      
      for(i = 0; i < 3; i++)
      {
        
          myArray[i] = i + 2;
          
      }
    }
    
    void printValues()
    {
      int i;
      
      for(i =0; i < 3; i++)
      {
        
        std::cout<<myArray[i]<<std::endl;
        
      }
      
    }
    private:
      int myArray[3];
    
};

int main(void)
{
  
  myClass myMain;
  myMain.printValues();
  std::cin.get();
  
  return 0;
}

Addressing your second question, if you want to pass an array of value_type, then you can accept an argument of type value_type*. Consider the following code:

Code:

#include <iostream>

using std::cout;
using std::endl;

typedef char value_type[3];

void do_stuff(value_type *arr)
{
    memcpy(arr[0],"ab",3);
    memcpy(arr[1],"cd",3);
    memcpy(arr[2],"ef",3);
    memcpy(arr[3],"gh",3);
    memcpy(arr[4],"ij",3);
}

int main()
{
    value_type a[5];
    memset(a,0,15);
    do_stuff(a);
    cout << a[0] << endl;
    cout << a[1] << endl;
    cout << a[2] << endl;
    cout << a[3] << endl;
    cout << a[4] << endl;
    return 0;
}

Originally Posted by Perverse

Hi this is my first post here and im really hoping i can get a little help on something which my be really easy anyways ....
I have never used typedef before i need to declare a typedef for a char acter array of 3 chars.

would this be correct:
typedef char value_type[3];

also i have to write a class and one of the private member variable is a array of type value_type from above. I need to write an accessor function it display the contents of the array, but you can not return arrays in c++, so would i go about return a refrence to that array??

Any help would be appreciated Thanks!

Regarding the second question....having a pointer that points to the address of that array would work fine. In the getArray() (Or whatever the accessor function is), just return that pointer....or you can de-reference it and print it out...

Anyhoo, a pointer would accomplish what you want to do by pointing to the address of the first element in the array.

Originally Posted by Perverse

would this be correct:
typedef char value_type[3];

Any help would be appreciated Thanks!

Well, it is valid C code and it is valid C++ code. Whether it is correct or not pretty much depends on what the question was.

(It says that variables declared as value_type are arrays of three chars.)

Code:

#include <iostream>
using std::cout;
using std::endl;

int main()
{
  typedef char value_type[3];
  value_type x = {'a', 'b', 'c'};
  value_type y;
  unsigned int i;

  cout << "sizeof(x) = " <<  sizeof(x) << endl;
  for (i = 0; i < sizeof(x); i++) {
    y[i] = x[i]+3;
  }

  for (i = 0; i < sizeof(x); i++) {
    cout << "x[" << i << "] = " << x[i] 
         << ", y[" << i << "] = " << y[i] << endl;
  }

  return 0;
}

Regards,

Dave