For a class recently the teacher challenged us to write a code snip-bit that would be self replicating. By that I mean write a program that when executed would write out its own source code. This is a bit harder than you’d initially think it to be. My first attempt tried to store the source code within the program when execute it would output what was stored within. However this creates a chick and egg problem. The source code contains the source code. Something that at first stumped me. Then I remembered Stringification in the C preprocessor and I came up with this:

#include “stdio.h”
#define M(Code) main(){FILE* fp = fopen(“source.c”, “w”);fprintf(fp,”#include \”stdio.h\”\n#define M(Code) %s\nM(%s)\n”,#Code,#Code);fclose(fp);}
M(main(){FILE* fp = fopen(“source.c”, “w”);fprintf(fp,”#include \”stdio.h\”\n#define M(Code) %s\nM(%s)\n”,#Code,#Code);fclose(fp);})

This is a pretty cute program if I can say so myself. When its ran it will create a file called source.c that will be exactly the same as the code above. You could even recompile source.c and it will create another source.c. You should attempt to do this on your own to see if you can come up with other cool ways of doing it.

Download: SelfRep.c

If  you are like me you don’t exactly see the usefulness of the social networking site Twitter. After reading a recent wired article I can not better see that usefulness. There appears to be some pretty clever people connecting common house hold devices to Twitter.

This really isn’t all that new of a concept however. People have been connecting bots to IRC for control for a very long time now. I would suspect similar devices have been plugged into IRC. I wonder about the secuirty behind putting so much control of your house onto the net. Losing control of your own account could give an attacker control of say your air conditioning and drop your house to 60 degrees. Causing your electric bill to ski rocket.