Notes: Tuesday 7 November 2002

Schedule

• Tuesday, 12 November: Problem Set 6
• Thursday, 14 November: Exam 2 Out
• Tuesday, 19 November: Exam 2 Due
• There will be no class on Tuesday 19 November or Thursday 21 November.

Exam 2
Exam 2 will be handed out Thursday, 14 November. The exam will be take home, open book and notes, and similar in format to Exam 1. It will cover everything in the course up to and including today including material in Lectures 1-18, Problem Sets 1-6 and all assigned readings. The exam will emphasize material that was covered after Exam 1, so you should not be surprised to encounter questions about subtyping, inheritance, concurrency, data abstraction in low-level languages, memory management and garbage collection. You should also not be surprised to find questions that cover material from the first half of the class also: writing good specifications, reasoning about data abstractions and design.

Pointers in C Why is it useful to be able to manipulate memory addresses directly?

Why is it dangerous to be able to manipulate memory addresses directly?

• &expr — Evaluates to the address of the location expr evaluates to
• *expr — Evaluates to the value stored in the address expr evaluates to
• expr1[expr2] — Syntactic sugar for *(expr1 + expr2)

int match (char *s, char *t) {
  char *os = s;
  while (*s++ == *t++);
  return s;
}

The International Obfuscated C Code Contest

#include <stdio.h>

char
*T="IeJKLMaYQCE]jbZRskc[SldU^V\\X\\|/_<[<:90!\"$434-./2>]s",
K[3][1000],*F,x,A,*M[2],*J,r[4],*g,N,Y,*Q,W,*k,q,D;X(){r  [r
[r[3]=M[1-(x&1)][*r=W,1],2]=*Q+2,1]=x+1+Y,*g++=((((x&     7)
-1)>>1)-1)?*r:r[x>>3],(++x<*r)&&X();}E(){A||X(x=0,g       =J
),x=7&(*T>>A*3),J[(x[F]-W-x)^A*7]=Q[x&3]^A*(*M)[2         +(
x&1)],g=J+((x[k]-W)^A*7)-A,g[1]=(*M)[*g=M[T+=A            ,1
][x&1],x&1],(A^=1)&&(E(),J+=W);}l(){E(--q&&l              ()
);}B(){*J&&B((D=*J,Q[2]<D&&D<k[1]&&(*g++=1                ),
!(D-W&&D-9&&D-10&&D-13)&&(!*r&&(*g++=0)                   ,*
r=1)||64<D&&D<91&&(*r=0,*g++=D-63)||D                     >=
97&&D<123&&(*r=0,*g++=D-95)||!(D-k[                       3]
)&&(*r=0,*g++=12)||D>k[3]&&D<=k[                          1]
-1&&(*r=0,*g++=D-47),J++));}j(                            ){
putchar(A);}b(){(j(A=(*K)[D*                              W+
r[2]*Y+x]),++x<Y)&&b();}t                                 ()
{(j((b(D=q[g],x=0),A=W)                                   ),
++q<(*(r+1)<Y?*(r+1):                                     Y)
)&&t();}R(){(A=(t(                                        q=
0),'\n'),j(),++r                                          [2
]<N)&&R();}O()                                            {(
j((r[2]=0,R(                                              ))
),r[1]-=q)                                                &&
O(g-=-q)                                                  ;}
C(){(                                                     J=
gets                                                      (K
[1]))&&C((B(g=K[2]),*r=!(!*r&&(*g++=0)),(*r)[r]=g-K[2],g=K[2
],r[
1]&&
O())
);;}
main
(){C
((l(
(J=(
A=0)
[K],
A[M]
=(F=
(k=(
M[!A
]=(Q
=T+(
q=(Y
=(W=
32)-
(N=4
))))
+N)+
2)+7
)+7)
),Y=
N<<(
*r=!
-A))
);;}

Why is there no International Obfuscated Java Contest?

Why is there no International Obfuscated Scheme Contest? (CS200 graduates only)

University of Virginia Department of Computer Science CS 201J: Engineering Software

Sponsored by the National Science Foundation

cs201j-staff@cs.virginia.edu