The Friday Fragment

It's Friday, and time again for a new Fragment: my weekly programming-related puzzle.

This Week's Fragment

This week's programming puzzle was sent in by Joel Odom:

Write C code or pseudo-code to swap the values of two integer (int) variables, a and b, without declaring or using any other variables. Do not use any syntactical language tricks that implicitly copy values out of a or b into other memory or registers. You can use C operators, control flow, and similar statements.

If you want to “play along”, post the solution as a comment or send it via email. To avoid “spoilers”, simply don’t expand comments for this post.

Last Week's Fragment - Solution

Last week's puzzle was the following programming-related cryptogram:

Baae jaanklb xpnrv xksr. Ki gaq pwr sper xa cpkx, kx kv xa vrwhr gaq urxxrw, ple xa ftrpvr gaq.

Congratulations to Luke for solving this; the plaintext answer is:

Good cooking takes time. If you are made to wait, it is to serve you better, and to please you.

This is a chapter intro quote in Fred Brooks' classic The Mythical Man Month, taken from a French restaurant menu. It reminds us that quality software also requires time and careful preparation.