Animating programs and students in the laboratory

Program animation is a well-recognized tool for the enhancement of understanding of algorithms and data structures. The difficulty of creating animations, however, has limited the use of animation by students. This is especially so in introductory courses where the students need to concentrate on the material to be learned and should not be distracted by irrelevant details of an animation system. We have developed a prototype system which allows students (or instructors) to create C/C++ programs which are self-animating. Use of this system does not require learning any extra programming skills. Users need only specify which variables and data structures they want to be animated. This is done by declaring those elements of the program to be "self-animating" types. Typically, this would mean substituting INT for int. Similar changes allow for the self-animation of arrays, structs, and pointers. At present, our implementation supports ints and types derived from ints using pointers, arrays, and structs. The resulting C/C++ program appears in an integrated display environment that provides animation of the selected data items, and also shows the source code with the currently animated instruction highlighted. The environment also organizes program information in a way that is meaningful to the programmer, and allows the programmer to control the degree of detail that he or she wants to see. This paper briefly describes the system and, by using examples, shows the ease with which students or instructors can create animations in the laboratory or classroom.