Converting bool expression to char in c#

Question

I passed .NET quiz, when I met a question like below one.

Char ch = Convert.ToChar('a' | 'e' | 'c' | 'a');

In console we can see that output for ch variable is g.

Can someone describe what is happening ? Thanks!

Answer 1

This is not what it looks like at first spot. It is more of binary calculations on the int representation of these Char:

Here is a full article explaining this with examples: Article

So the binary result for the bitwise Or of these 'a' | 'e' | 'c' | 'a' is 103. If you Convert that to Char, it is g

Edit:

I see this answer took more attention than I though it deserves more details.

From C# Compiler side:

There is an implicit conversion from char to int (int i = 'a' compiles), so what the compiler actually does is:

Convert.ToChar((int)'a' | (int)'e' | (int)'c' | (int)'a');

Since these are hard-coded values, the compiler does more work:

Convert.ToChar(97 | 101 | 99 | 97);

and finally:

Convert.ToChar(103); // g

If these were not hard-coded values:

private static char BitwiseOr(char c1, char c2, char c3, char c4)
{
    return Convert.ToChar(c1 | c2 | c3 | c4);
}

Using Roslyn you get:

private static char BitwiseOr(char c1, char c2, char c3, char c4)
{
    return Convert.ToChar((int)c1 | c2 | c3 | c4);
}

Converted to IL (or (Bitwise) IL instruction used):

.method private hidebysig static char  BitwiseOr(char c1,
                                                   char c2,
                                                   char c3,
                                                   char c4) cil managed
  {
    // 
    .maxstack  2
    .locals init (char V_0)
    IL_0000:  nop
    IL_0001:  ldarg.0
    IL_0002:  ldarg.1
    IL_0003:  or
    IL_0004:  ldarg.2
    IL_0005:  or
    IL_0006:  ldarg.3
    IL_0007:  or
    IL_0008:  call       char [mscorlib]System.Convert::ToChar(int32)
    IL_000d:  stloc.0
    IL_000e:  br.s       IL_0010

    IL_0010:  ldloc.0
    IL_0011:  ret
  } // end of method Program::BitwiseOr