What does it mean for an object to have invariants, and why does one need to worry about them?

2.)how does a graphical user interface (gui) on a touchscreen interface differ from a gui on a desktop or laptop? a.)a finger or stylus is used instead of a pointer. b.) a magic wand is used instead of a pointer. c.)users speak commands instead of using a pointer. d.)users visualize commands instead of using a pointer.

Two technicians are discussing the common u-joint. technician a says its input and output speeds should be equal. technician b says that it normally has two yokes. which technician is correct?

Design a class tictactoe that: holds the following information about the game: two-dimensional array (3 by 3), and winner. add additional variables as needed. includes the functions to perform the various operations on objects. for example, function to print the board, getting the move, checking if move is valid, determining if there is a winner after each move. add additional operations as needed. includes constructor(s). write the functions of the class, and write a program that uses the class. the program should declare an object of type tictactoe. the program will create the board and store it in the array. the program will allow two players to play the tic-tac-toe game. after every valid move update the array, check if there is a winner. if there is no winner and no tie, then print the board again to continue.