Broken String.this[]

[ishvedov]

Details about Problem

nanoFramework area: interpreter

Worked before? Yes, old firmware's. At least ESP32 668.

Detailed repro steps so we can see the same problem

Console.WriteLine("a\nb"[1].ToString());

return 'b', must '\'.

Can't check myself but what about adding a '@' in front of the string : Console.WriteLine(@"a\nb"[1].ToString());
This would not solve the issue but could be a temporary workaround ?

Also, how does this behave ? Console.WriteLine("a\\nb"[1].ToString());
(again, I can't test myself, I am away from home this week)

[ishvedov]

@MikroBusNet no workaround possible, because on this functionality based PR for CoreLib.

[josesimoes]

This is deeper than some wrong indexing of the string chars.
Seems to be related with wrong handling/conversion of the string on the CLR_RT_UnicodeHelper.

Test code:

        public static void Main()
        {
            // string with new line char, output one char at a time
            string s = "a\nb7#zx03";

            Console.WriteLine("char output for '" + @"a\nb7#zx03" + "' iterating trough string chars");

            for(int i = 0; i < s.Length; i++)
            {
                Console.WriteLine(" " + s[i] + " (" + ((byte)s[i]) + ")");
            }

            Console.WriteLine("");

            // string with new line char, output from ToCharArray()
            var sAsArray = s.ToCharArray();

            Console.WriteLine("");
            Console.WriteLine("char output for '" + @"a\nb7#zx03" + "' as a char array");
            Console.WriteLine("length of string 's' is " + s.Length);
            Console.WriteLine("length of char array is " + sAsArray.Length);
            Console.WriteLine("");

            foreach (char c in sAsArray)
            {
                Console.WriteLine(" " + c +" (" + ((byte)c) + ")");
            }

            // string withOUT new line char, output from ToCharArray()
            s = "1w+F5?=zQ";

            sAsArray = s.ToCharArray();

            Console.WriteLine("");
            Console.WriteLine("char output for '" + s + "' as a char array");
            Console.WriteLine("length of string 's' is " + s.Length);
            Console.WriteLine("length of char array is " + sAsArray.Length);
            Console.WriteLine("");

            foreach (char c in sAsArray)
            {
                Console.WriteLine(" " + c + " (" + ((byte)c) + ")");
            }

            Thread.Sleep(Timeout.Infinite);
        }

Output from the above in nF app:

char output for 'a\nb7#zx03' iterating trough string chars
 a (97)
 b (98)
 7 (55)
 # (35)
 z (122)
 x (120)
 0 (48)
 3 (51)
  (64)


char output for 'a\nb7#zx03' as a char array
length of string 's' is 9
length of char array is 9

 a (97)
 b (98)
 7 (55)
 # (35)
 z (122)
 x (120)
 0 (48)
 3 (51)
  (0)

char output for '1w+F5?=zQ' as a char array
length of string 's' is 9
length of char array is 9

 1 (49)
 w (119)
 + (43)
 F (70)
 5 (53)
 ? (63)
 = (61)
 z (122)
 Q (81)

Output from .NET 4.6 console app:

char output for 'a\nb7#zx03' iterating trough string chars
 a (97)

 (10)
 b (98)
 7 (55)
 # (35)
 z (122)
 x (120)
 0 (48)
 3 (51)


char output for 'a\nb7#zx03' as a char array
length of string 's' is 9
length of char array is 9

 a (97)

 (10)
 b (98)
 7 (55)
 # (35)
 z (122)
 x (120)
 0 (48)
 3 (51)

char output for '1w+F5?=zQ' as a char array
length of string 's' is 9
length of char array is 9

 1 (49)
 w (119)
 + (43)
 F (70)
 5 (53)
 ? (63)
 = (61)
 z (122)
 Q (81)