The difference between MyString[0] and MyString.ToCharArray()[0] is that the former treats the string as a read-only array, while ToCharArray() creates a new array. The former will be quicker (along with easier) for almost anything where it will work, but ToCharArray can be necessary if you have a method that needs to accept an array, or if you want to change the array.

If the string isn't known to be non-null and non-empty you could do:

string.IsNullOrEmpty(MyString) ? null : (char?)MyString[0] 

which returns a char? of either null or the first character in the string, as appropriate.

The difference between MyString[0] and MyString.ToCharArray()[0] is that the former treats the string as a read-only array, while ToCharArray() creates a new array. The former will be quicker (along with easier) for almost anything where it will work, but ToCharArray can be necessary if you have a method that needs to accept an array, or if you want to change the array.

If the string isn't known to be non-null and non-empty you could do:

string.IsNullOrEmpty(MyString) ? (char?)null : MyString[0] 

which returns a char? of either null or the first character in the string, as appropriate.