Returning array from a function C++

[cyberzero]

Hi Gurus,
I'm new to C++, but I have a small background in java. I want to convert the following java code to c++, but returning array is a big trouble for me. This code parses the header of a stream and manipulates it. Following is java code. I need the c++ code does the same thing: Thanks in advance.


public class JoinBytes
{
public static void main(String[] args)
{
byte[] a = {1,2,3,4,5,6};
byte[] b = {7,8,9};

byte[] sum = combineBytes(a, b);
for(int i=0; i<sum.length; i++)
{
System.out.println("Byte at position "+ i + " is: " + sum[i]);
}
}

static byte[] combineBytes(byte[] a, byte[] b)
{
int i=0;
byte[] result = new byte[a.length+b.length];
for(i=0; i<a.length; i++)
{
result[i] = a[i];
}

for(int j=0; j<b.length; j++)
{
result[i+j] = b[j];
}
return result;
}
}

Love
CYBERZERO

[Bazzy]

Use vectors instead of arrays and your problems would be easily solved

[kbw]

In C++, an array is just a sequence. Besides the type of the elements, nothing else is known, like the length for example. So in C/C++, whenever an array is used, it's length must be passed too. By convention, C strings have a sentinel entry (NULL) to indicate the end, but if this is missing, you get a buffer overrun (a source of hacks).

That's where STL collections come in. They know everything they need to know to get the job done, like the length for example.

[cyberzero]

Thanx KBW and Bazzy,

As per your advice I used vectors and the problem is solved. But I have to change all the dependent codes to accept the vector. Following is the same code done with vectors:


vector<byte> joinBytes(vector<byte> b1, vector<byte> b2)
{
vector<byte> tot;
int i = 0;
for(i=0; i<b1.size(); i++){
tot.push_back(b1[i]);
}

for(int j=0; j<b2.size(); j++){
tot.push_back(b2[i]);
}

return tot;
}

int main(int argc, char *argv[])
{
vector<byte> a1(2,5);
vector<byte> a2(10,12);
vector<byte> combined;
combined=joinBytes(a1, a2);
cout<<"Size of a1 is: "<<a1.size()<<endl;
cout<<"Size of a2 is: "<<a2.size()<<endl;

for (int i=0; i<combined.size(); i++)
cout << (short)combined[i]<<endl;
cout<<"The size of combined array is: "<<combined.size()<<endl;

system("PAUSE");
return EXIT_SUCCESS;
}


Thanks Again
CYBERZERO

[kbw]

It's conventional to pass in your collections by const reference if they don't need to be changed. const to enforce read-only operations, reference to not copy the collection.

In Java, reference is implied. In C++ it is not.

vector<byte> joinBytes(const vector<byte> &b1, const vector<byte> &b2)