UMBC CS 201, Fall 05

goto

Background

Programming languges in the 1950's and 60's made heavy use of the GOTO to modify control flow.
In the 1970's there was a general recognition that GOTOs made code harder to understand, analyze and maintain.
Structured programming used constructs like while and for were thought to be much better.

Warning

Don't use C's goto or label in CMSC201
Don't use them unless you (i) have become an expert programmer and (ii) can justify why they are needed or better than doing it another way.
We show this to you out of a desire for completeness.
Don't use the goto in C.

Go To Statement Considered Harmful, Edsger W. Dijkstra, Communications of the ACM, Vol. 11, No. 3, March 1968, pp. 147-148. For a number of years I have been familiar with the observation that the quality of programmers is a decreasing function of the density of go to statements in the programs they produce. More recently I discovered why the use of the go to statement has such disastrous effects, and I became convinced that the go to statement should be abolished from all "higher level" programming languages (i.e. everything except, perhaps, plain machine code). At that time I did not attach too much importance to this discovery; I now submit my considerations for publication because in very recent discussions in which the subject turned up, I have been urged to do so.

Break and Continue

The break statement

The break statement exits from a switch, while, do or for statement that it is in.

The continue statement

The continue statement starts the "next" iteration of the enclosing while, do or for.

Since both break and continue alter the natural control flow of a program, we don't allow you to use them in your loops in CMSC 201. The notable exception is that most cases of the switch should have a break statement in them.