I have a string that is retrieved from a socket. I display this string as the text of a button. Some strings contains a '\' which doesn't get printed because it's an escape character. So, I want to find all '\' and replace it with a "\\" so it will show up on the button.

The code below gets an error on the first line:
ERROR: newline in constant

index = OrigString->IndexOf('\');
if (index != -1)
{
substring1 = OrigString->Substring(0,index);
substring2 = OrigString->Substring(index+1);
OrigString = String::Concat(substring1, S'\', substring2);
}

What can I do to resolve this error?
My algorithm:
1) find index of '\' in string
2) split the string into 2 strings at index
3) Concatenate string1, '\', string2

You need to use

index = OrigString->IndexOf('\\');

I believe.

That line of code didn't work. I sent " /\ North " and had " / North " displayed on the button.

Am I to assume there's also a south, east, and west button? Why bother with the /\ at all, when you could position the buttons in a cardinal fashion?

The code for the button needs to be "/\\North".

Those are some examples. So, are you saying that it's not possible?

Not at all. What you want to do is pretty simple, and should be easy to do.
So if you're using substring and such, is this SDK?
I did something similar to what you're doing (finding and making a file path) yesterday, only using CStrings.

void CGUISnoopDoc::LoadConfig()
{
	CString strPath = FilePath;
	
	for(int i=0; i<2;i++)
	{
		strPath= strPath.Left(strPath.ReverseFind('\\')+1);
		strPath+="guisnoop.cfg";					 //Append file name.
		strPath.FreeExtra();
		std::ifstream file(strPath);
		if ( file )
		{
			char line[80];
			CString fmtStr;							//Formatting string.
			while (file.getline(line, sizeof line) )
			{
				if(line[0] != '#')
				{
					fmtStr=line;
					MACaddrMAP.insert(cCStr2CStr(fmtStr.Right(17),fmtStr.Left(5)));
				}
			}
			return;
		}
		else
		{
			//Try one directory level higher.
			if(strPath.ReverseFind('\\')!=2) // Make sure that the directory isn't root, ie, C: 
				strPath= strPath.Left(strPath.ReverseFind('\\')); //remove guisnoop.cfg and \.	
			else
			{
				MessageBox(NULL,"Using MAC Addresses","No Higher Directory",MB_OK);
				return;
			}
		}
	}
	
	MessageBox(NULL,"Using MAC Addresses","Unable to open guisnoop.cfg",MB_OK); 
	return;
}

Yes, it's probably horribly inefficient as a function, but that's how I picked out the wily '\' character.