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Topic: Obfuscated code (Read 19765 times) 

D
Guest

The code isn't so obfuscated when it's written like PROPER code.... #include <stdio.h> #define _ F>00  FOO; void F_OO(); long F=00,OO=00; void main() { F_OO(); printf("%1.3f\n", 4.0*F/OO/OO); } void F_OO() { ... } This is pretty much the first 3 lines expanded. The #define is a macro that defines the _ character. But it is only expanded for cases where the _ isn't used in a label (such as it is used in F_OO ). F_OO is actually a function that uses long drawn out operation on F and OO to make them become 202 and 16 respectively. 4 * 202 / 16 / 16 = 3.156 which is what is printed out. The 4. in the given code is really 4.0. the  sign is actually a unary minus making the 202 into 202, it doesn't do a subtraction. It wouldn't have been as obfuscated if it had been written 4.*F/OO/OO see? So, the code calls the F_00 function to change the values of F and OO, then prints out some math mangling of those values. The last thing that makes this code more complicated is that they didn't declare their return types for F_OO or main and attempted to assume then as void (which is invalid, proper C would default them to integers). I'll ignore errors associated with not declaring includes or function prototypes and assume those were just not put in the excerpt. D


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anton
Guest

Since 4.*F/OO/OO results in an approximation of Pi, we get: Pi = 4F/OO^{2} Pi*(OO/2)^{2} = F It makes sense to assume that OO is the diameter of a circle, and F is its area (negative). The circle is actually the one "drawn" in the function F_OO(). Later, I will replace F with a and OO with d. Let's see what happens in the F_OO function. Each line consists of "_" followed by a string of "_". Each "_" is replaced with "a>0  ad;" which means following:  Subtract one from a. (a)
 If, before the subtraction, a was negative then perform "ad", since the operator  executes its right part only when the left part is false. The meaningful action here is only "d"; that is, subtract one from d.
The underscore in each "_" is replaced with the same thing; the only difference is the initial minus sign. Now a is compared with zero; since a is always positive, the second part never gets executed. And now we get the full picture: each of "_" and "_" decreases a by one; thus, a contains the negative area of the circle. In addition, each initial "_" decreases d by one  in the end d becomes equal to the negative height of the circle, which is the same as its diameter.


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Paul
Newbie
Posts: 1


Re: Obfuscated code
« Reply #2 on: Apr 6^{th}, 2013, 10:07pm » 
Quote Modify

People keep showing fractions of pi.You all need to realise pi is a whole number and the rest of the numbers are the fractions.Point then nonpoint.The nonpoint should be a whole number?Ok,seems right doesn't it?


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