Copying Array Data to Another Array in Font

Printer PDF-417 2d barcode in Font Copying Array Data to Another Array

Microsoft programmed in several methods you can use to copy data form one array to another. One of them is the CopyTo() method. This method copies all the elements of the current array to another array starting at the specified destination array index: VB .NET Numbers.CopyTo(SomeNumbers,1) 'skip over (0) and start at (1) C# Numbers.CopyTo(SomeNumbers,1); //skip over [0] and start at [1]

In C#, an array s length cannot change once it is made and still keep its data. In reality, VB .NET works the same way, but that language has a command called ReDim with a Preserve option that allows you to keep the existing values. Behind the scenes, VB .NET is really making a new array, copying the old array s data to the new one, then reusing the variable name to point to the new copy. Since there is no ReDim or Preserve command in C#, you have to do this yourself. It sounds like more work than it really is; you just create a new copy of the array using the CopyTo() method and then set the original variable to point to the new array s memory location.

VB .NET Dim numbers As Integer() = {10, 20} 'Now the array has two elements Console.WriteLine(numbers(0)) 'Shows 10 'Create a copy and preserve the data (will use the same name) ReDim Preserve numbers(2) 'Now it has 3 elements (0)=10,(1)=20,(2)=0 Console.WriteLine(numbers(0)) 'Still Shows 10 'Change the size of the array ReDim numbers(2) 'without using Preserve, the data is lost. 'This time it shows 0, since .NET resets integers to zero for you Console.WriteLine(numbers(0)) C# int[] numbers = {10, 20}; //Now the array has two elements Console.WriteLine(numbers[0]); //Shows 10 //Create a copy and preserve the data (must use a different name) int[] MyCopy = new int[3]; numbers.CopyTo(MyCopy, 0); //[0]=10,[1]=20,[2]=0 Console.WriteLine(MyCopy[0]); //Still Shows 10 //Now, point the numbers array to the same memory //location as the MyCopy array to complete the resizing. numbers = MyCopy; //Changing the size of the array w/o using the CopyTo() method. numbers = new int[3]; // now it has three elements, but its data is gone //Shows 0, since .NET resets integer to zero for you Console.WriteLine(numbers[0]);

Both VB .NET and C# provide a simple, clean way to loop through all of the elements of an array called the For-Each/foreach loop. For example, the following code creates an array called numbers, accesses each element, and prints the contents to the screen. The statements inside of the loop will continue to run again and again until it runs out of elements to access. VB .NET Dim numbers As Integer() = {5, 10, 15} For Each i As Integer In numbers //start of loop Console.WriteLine(i) 'i contains a copy the data Next //end of loop

C# int[] numbers = { 5, 10, 15}; foreach (int i in numbers) //start of loop { Console.WriteLine(i); //i contains a copy of the data }// end of loop

Much like the CopyTo() method, this method copies a section of one array to another array. It has more options than the CopyTo() method. In this one, you can specify which element to start the copy from, where to place the copied elements, and how may elements you want to copy. It will even convert most types of data for you as needed. The syntax it a bit tricky at first, but becomes easy once you know what the parameters do. Microsoft created four different version of this, but let s look at the meaning of this one version: Array.Copy(Array, Int32, Array, Int32, Int32). Parameter 1 is the array that contains the data you want to copy; let s call it the Source-Array. Parameter 2 is the index in the Source-Array where you want to begin copying data. Parameter 3 is the Destination-Array, the array that will receive the copied data. Parameter 4 is the index that you want to start at when pasting your data to the Destination-Array. Parameter 5 is the number of elements you want to copy over from the Source-Array. So, you would read Array.Copy(Numbers, 1, SomeNumbers, 0, 2); as the following: Copy the data from Numbers to SomeNumbers. Start the copy at index 1. Place the copied data starting at the zeroth index of the SomeNumbers array. Only copy 2 of the elements. VB .NET Dim Numbers As Integer() = {5, 10, 15, 20} Dim SixNumbers(5) As Integer '//integers set to zero Array.Copy(Numbers, 1, SixNumbers, 0, 2) For Each i As Integer In SixNumbers Console.WriteLine(i) 'Shows 10 15 0 0 0 0 Next