String Data Types

After adding a new text box to a Microsoft .NET form written in C#, you can access its Text property and read the control's value. This value is a string data type and consists of Unicode characters. Unlike integers other numerical data types, strings are "reference" types. They represent objects that point data rather than the data itself. Extract a string variable's characters using the SubString method as in the following example:

string x = "1234";
string y = x.SubString(0, 2);

This SubString method returns "12," the first two characters stored in the variable named x.

Byte Data Types

Videos, text files, games and everything else on a computer consists of bytes. A byte is a computer unit made up of smaller units called bits. In C#, a byte represents an integer value between 0 and 255. The first statement below assigns 100 to a byte variable named byte1:

byte1 = 100;
char char1 = 'A';
byte1 = (byte)char1;

Chars are also Unicode characters that can also hold character data such as letters. The final two statements assign the letter "A" to a char variable and convert it into a byte.

Byte Arrays

Even though chars, bytes and strings are different data types, you can convert between them easily. A byte array is an array that has a byte type declaration, as shown below:

byte[] byteArray1;

These arrays often consist of raw binary data that might exist in an image or even a PDF. If your application retrieves such data over the Web, it arrives in binary format and may wind up in a byte array. Your application can use the byte array to reconstruct the item it retrieved, manipulate the data or store it in a database.

Converting Strings to Byte Arrays

Byte arrays also have the ability to hold string data. Convert a string variable into a byte array, as shown in the example below:

string string2 = "This is a string";
byte[] byteArray1= System.Text.Encoding.ASCII.GetBytes(string2);

The Text.Encoding.ASCII property allows the code to transform Unicode characters into ASCII. The GetBytes method converts the string into a byte array and stores it in the byteArray1 variable.

Tips

You can loop through the elements in a byte array and examine them as seen in the following example:

foreach (byte byteItem in byteArray1)
{
MessageBox.Show("Numeric value=" + byteItem + " Character value=" + (char)byteItem);
}

This code iterates through the byte array 16 times because the original string contains 16 characters. A message box appears each time the code loops and displays the numerical value of the current data item and its character representation. Looping through a byte array is an excellent way to examine the numerical ASCII values of all the characters in a string.