I am writing a program that is to add a point to a linked list of points. I''m trying to do error checking to see if the point is in the specified range and that it isn''t a character. I get an error when I enter a -1, which just locks the system. The point should be between 0 and X. Can anyone help me with my problem? The source code for the function is below

    
void AddPointRoutine() 
{
	//refresh the openGL window to get rid of the menu

	glutPostRedisplay();
	
	cout << "..--==<ADD POINT>==--.." << endl;
	char Input[4];	
	//get the number of the verticies the user would like it to be.

	int pos = -1;
	while (pos <= 0 || pos > Obj1.GetNumVerticies()+1)
	{
		cout << "What point would you like it to be? (Valid Range 1-" << Obj1.GetNumVerticies()+1 << ") :";
		cin >> Input;

		//error checking, see if it is actully in the specified range
		if (sscanf(Input, "%f", pos) != 1)
			cout << "That is not a valid input, it must be a positive integer." << endl;
		else
		if (pos <= 0 || pos > Obj1.GetNumVerticies()+1)
			cout << "That is not a valid position number." << endl;
	}

	//now get the x coordinate


	//and the y coordinate



	cout << "Point Added Successfully" << endl;
	glutPostRedisplay();
}
    

some errors:
* sscanf(Input,"%f",pos) puts a float into an int!!!
* the function call should be sscanf(Input,"%d",&pos);
* from MSDN:

Return Value of sscanf(...)

Each of these functions returns the number of fields successfully converted and assigned; the return value does not include fields that were read but not assigned. A return value of 0 indicates that no fields were assigned. The return value is EOF for an error or if the end of the string is reached before the first conversion.
So I don''t see why you check if sscanfs return is not 1... Do you only want an integer of 1 digit?
it should be:

    		if (sscanf(Input, "%d", &pos) == EOF)			cout << "That is not a valid input, it must be an integer." << endl;    

You check it to be positive when you if(pos<=0||.....

"Everything is relative." -- Even in the world of computers.

The correct code (runs perfectly)

    	cout << "..--==<ADD POINT>==--.." << endl;		char Input[4];	int pos = -1;	int result;		while (pos <= 0 || pos > Obj1.GetNumVerticies()+1)	{				cout << "What point would you like it to be? (Valid Range 1-"<<Obj1.GetNumVerticies()+1<<") :";		cin >> Input;				//error checking, see if it is actully in the specified range		result=sscanf(Input, "%d", &pos);		if (result<1||result==EOF)			cout << "That is not a valid input, it must be an integer." << endl;		else			if (pos <= 0 || pos > Obj1.GetNumVerticies()+1)				cout << "That is not a valid position number." << endl;		}		//now get the x coordinate	//and the y coordinate		cout << "Point Added Successfully" << endl;    

"Everything is relative." -- Even in the world of computers.

Thank you soo much, I should have caught that error myself, but I guess that is what I get when I cut and copy my old code.