Mayank's C/C++ Challenger - II

Replies

• 

  xheavenlyx

  int main()
    {
                int *p = NULL ;   /* This line inits a pointer p(address) which points to a NULL value*/
                int *&ref = p ;   /* !!In short, ref=p :) */
                *ref = 5 ;        /* put value 5 where ref(address i.e p) points to. */
                cout << *p << endl ; /* Output 5? */
                return 0 ;
    }

  ​

  
  
  Well If I am correct on the line of
  
  int *&ref = p;
  
  then I guess my ans can be correct. Good Q though but practically its a hell-code. ^_^
  
  Regards
  
• 

  Mahesh

  I think its run time error because there is no reference pointer in C++.
• 

  Mayank

  xheavenlyx

  int main()
    {
                int *p = NULL ;   /* This line inits a pointer p(address) which points to a NULL value*/
                int *&ref = p ;   /* !!In short, ref=p :) */
                *ref = 5 ;        /* put value 5 where ref(address i.e p) points to. */
                cout << *p << endl ; /* Output 5? */
                return 0 ;
    }

  ​

  
  
  Well If I am correct on the line of
  
  int *&ref = p;
  
  then I guess my ans can be correct. Good Q though but practically its a hell-code. ^_^
  
  Regards
  

  Hi,
  
  Output is not 5.
  You have interpreted other statements well, but have just missed out the actual result. Try to read your own conclusions and hit the correct solution.
  All the best.:smile:
  
  
  Thanks and Regards,
  Mayank Shukla.
• 

  xheavenlyx

  Oh yeah!, I think ref is a reserved token word and cannot be used as a pointer. As Mahesh has pointed above 😀
  
  I dont have a compilet to check this but lets see. Wait for some more to reply befor u give the ans.
  
  Regards
• 

  Mayank

  Mahesh

  I think its run time error because there is no reference pointer in C++.

  Hi,
  
  You are close I should say.
  In C++, there cant be pointer to references, coz pointer points to memory locations and we dont have any specific memory locations allocated to references.
  BUT, here we are using refrence to pointer, which is absolutely allowed in C++.:smile:
  So you are right for Runtime error, but try for a correct explanation.
  Good TRY.
  
  
  Thanks and Regards,
  Mayank Shukla.
• 

  Mayank

  xheavenlyx

  Oh yeah!, I think ref is a reserved token word and cannot be used as a pointer. As Mahesh has pointed above 😀
  
  I dont have a compilet to check this but lets see. Wait for some more to reply befor u give the ans.
  
  Regards

  Hi,
  
  Mahesh has pointed out something else friend. Check my earlier replies.
  Anyways "ref" is definitely not a reserved keyword in C++.
  
  
  Regards,
  Mayank Shukla
• 

  xheavenlyx

  OH!!!
  
  The line &*ref=p will assign p to ref. (i.e: ref=p) but this isnt allowed, so a runtime error! 😀
  
  Since ref is already a refrenced memory location and cannot be changed explicitly. ITs like doing this:
  
  int a=0;
  const b=4;
  
  b=a; /not possible
  
  if(b==a)
  then
  blah;
  else
  blah; /Is correct.
• 

  aushinaire

  int *&ref = p;
  
  since a reference variable is basically another name for an existing variable, whats happening here is that we've created another name with which we can call the pointer p.
  so this line :
  *ref = 5;
  is the same as saying
  *p=5;
  unfortunatey though, the pointer p points to null, so there's no memory location to put the value 5 into.
  so my guess would be that there would be a runtime error, coz the variables p and ref, are pointing to empty space.
  
  let me know if my stab in the dark hit anywhere near target..
• 

  sahana

  hi.
  so *p=NULL;
  this is same as
  int *p;
  p=NULL;
  this statement means that p will point to nothing.hence p will store nothing. if we try to print the value of *p it will throw an exception saying that it is "NULL POINTER ASSIGNMENT".so it is a run time error.
• 

  xheavenlyx

  Well, I guess *p=Null does not mean p=NULL. it means well, *p=NULL, ie p points to a NULL value but I have a feeling NULL has stopped working in c++.
  
  Long back we tried to assign an array NULL value meaning empty, but it didnt work.
  
  int a[20]=null /nope
  int a[20]={} /yes
  
  Something of this sort, I cant think a lot on this for now 😀
• 

  aushinaire

  xhx, might'v worked if u had used
  
  int a[20];
  a=null;
• 

  Kaustubh Katdare

  Mayank, I guess its time for you to drop in! 😀
  
  Waiting for Challenger - III
  
  -The Big K-
• 

  Mayank

  BINGO!!! 😁
  aushinaire and sahana has answered it correctly.
  
  I apologize for not remaining in touch with you people for a bit long.
  Friends it was some important work that I was stucked up with.
  Sorry Again. 😡
  
  XHX,
  "The line &*ref=p will assign p to ref. (i.e: ref=p) but this isnt allowed, so a runtime error! "
  Actually, the line goes as
  int *&ref = p ;
  which is absolutely correct. Here ref is defined as a reference to a integer pointer 'p'. So nothing wrong with it.
  
  aushinaire has correctlty answered to xheavenlyx in the last post relating to the NULL assignment to an array.
  
  I'll be coming up with another question pretty soon. 😁
  
  
  
  Thanks and Regards,
  Mayank shukla.
• 

  Kaustubh Katdare

  That was super, Mayank. Waiting for Challenger - III 😁
  
  -The Big K-