help: simple problem

This is a discussion on help: simple problem within the C Programming forums, part of the General Programming Boards category; hi, just started c prog for college. useless at it. need help finding out what this comes to.its for exam. ...

  1. #1
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    help: simple problem

    hi,

    just started c prog for college. useless at it. need help finding out what this comes to.its for exam.

    three parts:

    a =3, b=2, c=4,

    what values of following if legal:


    b<a<c

    a*b%c+3

    --b*c+a


    need help especially with --b;

    also what does <<a or >>a mean

  2. #2
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    Quote Originally Posted by screamer903
    need help especially with --b;
    -- is unary decrement operator which evaluates to
    Code:
    --b;//same as
    b = b -1;
    So, it'll decrement the value of b first and then only will it return the final value of b.
    Quote Originally Posted by screamer903
    also what does <<a or >>a mean
    Have a look at the shift operators explanation in the FAQs then if there is something specific you're unclear about post back.

  3. #3
    Code Goddess Prelude's Avatar
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    >b<a<c
    Legal, but it doesn't do what you may expect. At first glance one might expect this to say "true if b is less than a and a is less than c", but in reality it compares the boolean result of b < a (0 or 1) to c. b is 2 and a is 3, so b < a is true. c is 4, so 1 < 4 is also true.

    >a*b%c+3
    This is an easy one, all operations go from left to right. So it's:
    Code:
    ( ( 3 * 2 ) % 4 ) + 3
    My best code is written with the delete key.

  4. #4
    C++ Developer XSquared's Avatar
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    >>the boolean result of b < a (0 or 1)
    I was always under the impression that true was represented as anything nonzero, and that it wasn't guaranteed to be 1. That would mean that the statement is totally unpredictable, but I probably missed something somewhere.
    Naturally I didn't feel inspired enough to read all the links for you, since I already slaved away for long hours under a blistering sun pressing the search button after typing four whole words! - Quzah

    You. Fetch me my copy of the Wall Street Journal. You two, fight to the death - Stewie

  5. #5
    Just Lurking Dave_Sinkula's Avatar
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    Quote Originally Posted by XSquared
    I was always under the impression that true was represented as anything nonzero
    "On input":
    http://www.eskimo.com/~scs/C-faq/q9.2.html
    7. It is easier to write an incorrect program than understand a correct one.
    40. There are two ways to write error-free programs; only the third one works.*

  6. #6
    Code Goddess Prelude's Avatar
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    >I was always under the impression that true was represented as anything nonzero
    Correct. True is non-zero and false is zero. However, boolean expressions are well defined and always evaluate to either 0 or 1.
    My best code is written with the delete key.

  7. #7
    Gawking at stupidity
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    It makes for neat little tricks like replacing:
    Code:
    if(a > b)
      c++;
    with:
    Code:
    c += a > b;
    If you understand what you're doing, you're not learning anything.

  8. #8
    Code Goddess Prelude's Avatar
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    That's not nearly as practical as my brilliant binary search tree trick:
    Code:
    struct node {
      T data;
      struct node *link[2];
    };
    
    struct node *insert ( struct node *tree, T data )
    {
      if ( tree == NULL ) {
        tree = make_node ( data );
      } else {
        int dir = data > tree->data;
        tree->link[dir] = insert ( tree->link[dir], data );
      }
    
      return tree;
    }
    It gets better and better as the symmetric cases get longer and longer.
    My best code is written with the delete key.

  9. #9
    Registered User coolshyam's Avatar
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    Smile Well I Do Have The Explanation

    a*b%c+3

    in this apply the BOMDAS rule
    that is bracket
    of
    multiply
    divide
    add
    substract

    --b*c+a
    --b will decrease the value od b by one unit
    the remaining will Follow bomdas rule

    >>a and <<a are the right shift and left shift operators which will shift the binary blase either right or left

    for example,
    10 = 1010(in binart system)
    >> 10= 0101 =5 (here, the binary digits got shifted to a place right)

    any questions any type in programming

    a ready made answer
    -----------------------------------------------------------------------------------
    FORTUNE FAVOURS THE BOLD!
    -----------------------------------------------------------------------------------

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