What will be the output of the following code and WHY?
Code:#include <stdio.h> void main() { int x,y,z; x=y=z=1; z=++x||++y&&++z; printf("x=%d y=%d z=%d\n",x,y,z); }Code:#include <stdio.h> void main() { float a=0.7 if (0.7>a) printf("Hi"); else printf("Hello"); }
Have you compiled and run it?
int main()
All problems in computer science can be solved by another level of indirection,
except for the problem of too many layers of indirection.
– David J. Wheeler
http://faq.cprogramming.com/cgi-bin/...&id=1043284376
So? Is the output as you expect? Or not? And you don't understand why not?yes i have executed it.
All problems in computer science can be solved by another level of indirection,
except for the problem of too many layers of indirection.
– David J. Wheeler
int main() is always not needed. void main() is also correct. The program has output.Originally Posted by vart
yes i have executed it.
No, the output is not as expected. I can't understand it.
Perhaps the compiler doesn't allow the increment operator to be applied more than once on the same sentence that uses && and ||. Switching x and y results in y having a value of 2 and x of 1 (as opposed to x = 2 and y = 1) so only the first variable is actually incremented. if we use a fourth variable 'w' to receive the assignment of the operation, 'w' receives the value of 1 and z is not incremented (when we print all four variables). Apparently incrementing more than one variable is not even recognized by the compiler. Then again, that's just my educated guess.
Look at the following code
What do you think will happen if pThing is NULL?Code:if(pThing && pThing->bUsed)
Try to figure out why...
Try to figure out what is happening in your case
All problems in computer science can be solved by another level of indirection,
except for the problem of too many layers of indirection.
– David J. Wheeler
The other part is a good puzzle. I think only an expert could answer for sure, why the computer says 0.7 is greater than the value of a variable initialized by
Could it be the internal representation of both numbers (a constant and a variable)? or possibly how the > operator internally in the microarquitecture. I have no clue, but it does lead to think about what lies below the compiler and the executed code.Code:float a = 0.7;
Read this http://cboard.cprogramming.com/showt...ight=scientist
for example
All problems in computer science can be solved by another level of indirection,
except for the problem of too many layers of indirection.
– David J. Wheeler
Try this and try to figure out the difference
KurtCode:#include <stdio.h> int main() { float a=0.7; if (0.7f>a) printf("Hi"); else printf("Hello"); }
Don't talk such nonsense!
Read this: http://www.research.att.com/~bs/bs_faq2.html#void-main
Also, you're lying! the second program is missing a semi-colon and CANNOT compile. If you want to know why it does what it does when you add the missing semicolon, you'll need to read this:
http://docs.sun.com/source/806-3568/ncg_goldberg.html
This line has what is called "undefined behaviour":
z=++x||++y&&++z;
You may not modify a variable more than once without intervening sequence points.
See http://msdn.microsoft.com/library/de...m/expre_11.asp.
Last edited by iMalc; 01-01-2007 at 12:05 AM.
thanks for the help.
I also thought like you. But need clarifications. Thanks for giving a try.
If a left part of the || is +ve, it is obvious that the output will be 1 therfore compiler doesnot calculate the other side of the ||. It ignores it.
Similarly if left side of && is 0 the result is obviously 0 therfore compiler discards the other part.
