Question

I’m writing a C#/WinForms application that contains a DataGridView with 2,000 rows. My users will enter strings into these rows. The strings may be in any language but the two most likely languages are English and Arabic. I don’t have an explicit limit on the maximum number of characters in a string, per se, but what I do have is a limit of 2048 bytes to store each string when it is written to disk. If the resulting byte array is < 2048 bytes, I need to pad it with null characters. I’m assuming that UTF-8 would probably be the most efficient encoding for storing these strings? If so, then I was thinking that I would do something like this before allowing the string to be stored:

byte[] stringAsBytes = System.Text.Encoding.UTF8.GetBytes(myString);
if (stringAsBytes.Length > 2048)
{
    // string is too long to be stored in 2048 bytes
}

If I understand correctly, since UTF-8 is a variable-length encoding, the maximum number of characters in a given string will be dependent on the code point range for the characters that comprise the language of the string? If that’s right, would I really need to do something like the code above for each key press to determine exactly when the string has exceeded the maximum size for storage?

Answer 1

No, you can use the following code:

var encoding=Encoding.UTF8;
var requiredBytes=encoding.GetByteCount("hello world!");

Alternatively, you could limit string length to

2048 / encoding.GetMaxByteCount(1)

which would guarantee all strings of your encoding fit into the buffer. Unfortunately, that’s only 341 chars for UTF8.