Re:Learn C The Hard Way
by JoshTriplett on Sunday July 03, 2011 @12:25AM
(#2723072)
I've watched and spoken to a large number of beginning C and C++ programmers (and beginning programmers in general) during their first terms of programming in university. I've noticed a few common problems, and I think they all stem from not understanding the details of how a program runs on a real machine:
- The concept of a variable, and variables changing over time, seems quite difficult for people to grasp even when explained a few different ways. "x = 5" followed by "x = 12" proves quite mystifying, and "x = x + 1" even more so. People seem to have the most success with the idea that declaring a variable "int x" creates a location x which can hold an int, and you can put things in that location.
- Pointers actually don't seem to trip that many people up initially, once they get to that point. However, I don't think people actually understand exactly what they do, so much as memorize the rules for dealing with them. The same idea of a location to put something applies here too.
- Any case where the same function gets called more than once often ends up tripping people up; this applies particularly to recursion, but it can happen even when just calling the same function several times. In particular, this often interacts badly with people's understandings of variables. People need some understanding of scope.
- Combining several of the above, it would help to have clear explanations of the interactions between pointers, locations, and functions. Bonus for explaining what goes horribly wrong if a pointer refers to something that goes out of scope. That concept requires understanding several different pieces of C and putting them together.
- The concept of a variable, and variables changing over time, seems quite difficult for people to grasp even when explained a few different ways. "x = 5" followed by "x = 12" proves quite mystifying, and "x = x + 1" even more so. People seem to have the most success with the idea that declaring a variable "int x" creates a location x which can hold an int, and you can put things in that location.
- Pointers actually don't seem to trip that many people up initially, once they get to that point. However, I don't think people actually understand exactly what they do, so much as memorize the rules for dealing with them. The same idea of a location to put something applies here too.
- Any case where the same function gets called more than once often ends up tripping people up; this applies particularly to recursion, but it can happen even when just calling the same function several times. In particular, this often interacts badly with people's understandings of variables. People need some understanding of scope.
- Combining several of the above, it would help to have clear explanations of the interactions between pointers, locations, and functions. Bonus for explaining what goes horribly wrong if a pointer refers to something that goes out of scope. That concept requires understanding several different pieces of C and putting them together.