string::find() returns -1 when comparing input string to string in binary tree

[moonman239]

Hi,

Given an input string - named "strIn" - I need to find a string in a binary tree that begins with strIn. To test my code, I inputted "SAN", which should have caused my program to output "SANTORRO, KARREN". Instead, the loop returns a different value in the tree.
According to my debugger, the program gets to the correct leaf, but find() fails to find strIn within the leaf. Here is my code:

string bTreeClass::Search(string strIn)
{
	string strOut;
	
	// Binary trees are organized so that the lower leaf is on the left
	// Start with the root leaf(current leaf is the root leaf
	LeafClass *currentLeaf = rootLeaf;
	//	Loop until match found or current leaf has no links
	while (true)
	{
		int find = currentLeaf->GetString().find(strIn);
		//	If strIn is in currentLeaf's string
		if (currentLeaf->GetString().find(strIn) == 0)
			// Match found
			// Exit Loop
			break;
		//	 Else if search data is less than current leaf data
		else if (strIn.compare(currentLeaf->GetString()) < 0) {
			//	If current leaf does not have a left node
				if (currentLeaf->GetLeftLink() == nullptr)
					//	Match failed
					//	Exit loop
					break;
			//	Else current leaf does have a left node
				else
					//	Advance current leaf to current leaf's left node
					currentLeaf = currentLeaf->GetLeftLink();
				//	End if
			}
		// Else (search data is greater than current leaf data)
		else {
			//	If current leaf does not have a right node
			 if (currentLeaf->GetRightLink() == nullptr)
					//	Match failed
					//	Exit loop
					break;
				//	Else current leaf does have a right node
				else
					//	Advance current leaf to current leaf's right node
					currentLeaf = currentLeaf->GetRightLink();
				//	End if
			//	End if
			}
		//	End loop	
		}
	strOut = currentLeaf->GetString();
	return strOut;
}

Please help and thank you!

[tcs]

If no match exists in your tree currentLeaf will finally have a non-null value and this will be returned.

[cire]

There is not enough context here to determine the cause of your issue. When asking others to troubleshoot your code, you should provide a minimal code sample that compiles and reproduces the problem that you are experiencing.

[moonman239]

@cire: In the sample I created using the same logic code, I was unable to reproduce the bug.

[cire]

In the sample I created using the same logic code, I was unable to reproduce the bug.

That suggests that the actual problem isn't with this code, but in some other code and happens to manifest here.

[moonman239]

@cire: You're right. I found the reason why the code didn't work for me, and it was because of how my fellow programmer treated a TCHAR in the main code file. His code looked like this:

string strIn;
for (int i=0;i=MAX_LOADSTRING;i++)
strIn = strIn + (char)szString[i];

where szString is a TCHAR array.

Now, for future readers, casting a TCHAR to a char is dangerous, because a TCHAR can be either a char or a wchar_t, depending on how Visual Studio is set. The default setting is wchar_t. My fellow programmer had his copy of Visual Studio set to char, while mine was the default.

Fortunately, we can copy a wchar_t array into a char array using the wcstombs_s function.