Rewrite Function Using Pointers

This is a discussion on Rewrite Function Using Pointers within the C Programming forums, part of the General Programming Boards category; Hi all, I'm new here and I'd first like to say hi! Anyway, I've been programming in Java for a ...

  1. #1
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    Rewrite Function Using Pointers

    Hi all, I'm new here and I'd first like to say hi! Anyway, I've been programming in Java for a while, and one of my courses recently required that I pick up C. I've tried searching and reading up on pointers already, but would still require help with the following:

    Actual Code:
    Code:
    int mystery1(int n) {
    	int bit;
    	if (n == 0)
    		return 0;
    	else {
    		if (n & 1)
    			bit = 1;
    		else
    			bit = 0;
    		return bit + mystery1(n/2)*2;
    
    	}
    
    }
    To be rewritten using the following function prototype:
    Code:
    void mystery1(int *n, B C)
    Where B and C are just placeholders. I'd just need some help in pointing me in the right direction, such as what B and C are? Thanks!

  2. #2
    Malum in se abachler's Avatar
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    Do your own homework.

    B and C are nothing, unless teh instructor gave you instructions on what they are and you didnt provide that to us.

    That function also is subject to an infinite loop for any even value over 1
    Last edited by abachler; 08-28-2008 at 12:59 PM.

  3. #3
    and the Hat of Guessing tabstop's Avatar
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    Why would it be an infinite loop?

    And you would need at least a type in the prototype.

  4. #4
    Malum in se abachler's Avatar
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    Quote Originally Posted by tabstop View Post
    Why would it be an infinite loop?

    And you would need at least a type in the prototype.
    oh my bad, i was readign it as returning mystery1((n/2)*2), i see now its not an infinite loop, it just coutns the number of bits that are 1's
    Until you can build a working general purpose reprogrammable computer out of basic components from radio shack, you are not fit to call yourself a programmer in my presence. This is cwhizard, signing off.

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    abachler: I've done my homework and that's why I'm asking here. I'm not even asking for the code, I just want to know what B and C might be.

    And no, it will not generate an infinite loop. What actually happens is that for a positive number x, the output will also be x. Doing a printf() of bit will show the number in it's binary form. When the input is a negative number x, the output will be the positive form of x.

    Also, what I've written is what I'm given. I too, would like to at least know if B C is "int bit" or something, but that was not given =(.

  6. #6
    Malum in se abachler's Avatar
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    there is no way of knowign what it could be, its undefined, and will generate a ciompile error. There is no logical way of determining what it migth be either, it coudl be anything. Ask teh instructor what he intends it to be.
    Until you can build a working general purpose reprogrammable computer out of basic components from radio shack, you are not fit to call yourself a programmer in my presence. This is cwhizard, signing off.

  7. #7
    Code Goddess Prelude's Avatar
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    >I too, would like to at least know if B C is "int bit" or something, but that was not given =(.
    What is this, an algebra problem? "Fill in the blanks" with C code? Clearly the function should be rewritten like this if your teacher really didn't elaborate at all on what needs to be done:
    Code:
    #include <stdio.h>
    
    int mystery1 ( int *n, const char *msg )
    {
      if ( msg != NULL )
        puts ( msg );
    
      return *n;
    }
    
    int main ( void )
    {
      int x = 12345;
    
      printf ( "%d\n", mystery1 ( &x, "Mr. Teacher Guy, you're a doofus." ) );
    
      return 0;
    }
    My best code is written with the delete key.

  8. #8
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    Thanks for the replies so far. Anyway, the original function returns an int, while the prototype is a void function. Apparent B is the type and C is the identifier. Since the function has no return type now, I'm guessing that *n is used instead to some sort of give a return value. I still can't figure out what B C should be for now.

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