Call StrTok() second time caused Access Violation Reading

Hi Everyone,

I am coding StrTok() which functioned as strtok predefine in cpp library. When it called this function second time and I got Access violation Error. Please see this piece of code.

Code:

char* StrTok1(char* strToken, const char* strDelimit)
{
	static char* strTokenCopy;
	static char* CurDelimitPos;
	char* CurToken = new char();//reset it every time
	char* ReturnCurToken = CurToken;//always points to CurToken
	
	if(strToken != NULL)
	{
		strTokenCopy = new char;
		//copy all elements
		for(char* strTokenPtr = strTokenCopy ; *strToken; *strToken++)
		{
			*strTokenPtr++ = *strToken;
		}
		*strTokenPtr = NULL;
		CurDelimitPos = strTokenCopy;//set CurDelimitPos points to first char of strTokenCopy
	}
	else
	{
	
		
		//advance to next position in stkTokenCopy
		*CurDelimitPos++;
	}
	
	for(char* Token = CurDelimitPos; *Token; *Token++)
	{
		const char* Delimit;
		
		//check if Token matchs any Delimit
		for(Delimit = strDelimit; *Delimit;)//Delimit looks in strDelimit
		{
			if(*Token != *Delimit)
				*Delimit++;
			else//found Token in strDelimit
			{
				*CurToken = NULL;
				CurDelimitPos = Token;	
				break;
			}			
				
		}//end for
		if(*Token == *Delimit)
		{
			break;//get out Token for loop
		}
		if(*Delimit == NULL)
		{
			*CurToken++ = *Token;//copy Token to CurToken
		}
	}//end for
	
	
	return ReturnCurToken;
	
		
	
}
void main(void)
{
	char string[] = "A string\tof ,,tokens\nand some more tokens";
	char seps[] = " ,\t\n";
	char* token;

	cout<<"Tokens:\n";
	token = StrTok1(string, seps);
	cout<<"\""<<token<<"\""<<endl;
	token = StrTok1( NULL, seps);
	cout<<"\""<<token<<"\""<<endl;
	token = StrTok1( NULL, seps);
	cout<<"\""<<token<<"\""<<endl;

}

When I debugged it and it showed this "char* CurToken = new char();" gave me Access Violation Error. I don't see anything wrong with it.
Thanks in advance.

Code:

char* CurToken = new char();
strTokenCopy = new char;

Ok, on this first line of code, is there a reason for the parenthesis?
Second, when you new a variable, you need to delete it when you are done with it. Try removing the parenthesis on that first line of code, and at the end of the function, add this:

Code:

delete CurToken;
delete strTokenCopy;

On a side note: I didn't take a good look at your code, but does your StrTok1() function do anything different than strtok()? What is the purpose of it? There may be a better way to accomplish what you need.

Thank for your comment.
I should not delete CurToken and strTokenCopy. CurToken is return by the function and strTokenCopy is static char pointer and its value is needed in every call.
To answer on side notes: this StrTok1 is working exactly as the original strtok().
Again any idea on why it gave me an error?

> char* CurToken = new char();//reset it every time
This allocates room for one char.

> strTokenCopy = new char;
Same as above, this only allocates room for a single char.

Originally Posted by brucejunor

I should not delete CurToken and strTokenCopy. CurToken is return by the function and strTokenCopy is static char pointer and its value is needed in every call.

You still should delete those variables. Anything you initialize with new should be freed with delete, else you get memory leaks.