The first 128 code points (0–127) of Unicode correspond to the letters and symbols on a standard U.S. keyboard. These first 128 code points are the same as those the ASCII character set defines. The second 128 code points (128–255) represent special characters, such as Latin-based alphabet letters, accents, currency symbols, and fractions. Unicode uses the remaining code points (256-65535) for a wide variety of symbols, including worldwide textual characters, diacritics, and mathematical and technical symbols.

You can use methods like IsDigit and IsPunctuation on a Char variable to determine its Unicode classification.

Visual Basic does not convert directly between Char and the numeric types. You can use the Asc, AscW Functions to convert a Char value to an Integer that represents its code point. You can use the Chr, ChrW Functions to convert an Integer value to a Char that has that code point.

If the type checking switch (Option Strict Statement) is on, you must append the literal type character to a single-character string literal to identify it as the Char data type. The following example illustrates this.

Option Strict On
Dim charVar As Char
' The following statement attempts to convert a String literal to Char.
' Because Option Strict is On, it generates a compiler error.
charVar = "Z"
' The following statement succeeds because it specifies a Char literal.
charVar = "Z"C

• Negative Numbers. Char is an unsigned type and cannot represent a negative value. In any case, you should not use Char to hold numeric values.

• Interop Considerations. If you interface with components not written for the .NET Framework, for example Automation or COM objects, remember that character types have a different data width (8 bits) in other environments. If you pass an 8-bit argument to such a component, declare it as Byte instead of Char in your new Visual Basic code.

• Widening. The Char data type widens to String. This means you can convert Char to String and will not encounter a System..::.OverflowException error.

• Type Characters. Appending the literal type character C to a single-character string literal forces it to the Char data type. Char has no identifier type character.

• Framework Type. The corresponding type in the .NET Framework is the System..::.Char structure.