easy way to check ordering of numbers?

This is a discussion on easy way to check ordering of numbers? within the C++ Programming forums, part of the General Programming Boards category; I want to check the ordering of numbers in an if statement, for example, in pseudo-code: Code: if a < ...

  1. #1
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    easy way to check ordering of numbers?

    I want to check the ordering of numbers in an if statement, for example, in pseudo-code:
    Code:
    if a < b < c < ... < z
    then do something magical
    else quit
    Is there an easy way to do this? Obviously doing all the boolean comparisons is not possible. Maybe sorting the numbers and then doing the respective comparisons is the best way?

  2. #2
    Use this: dudeomanodude's Avatar
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    Yes, a sort() will accomplish a sort. But what do you mean by "order"? Like as in a polynomial?
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    Oh sorry, by 'order' I meant just numerical order. For example
    Code:
    3 < 4 < 5 < 6
    should be true and
    Code:
     3 < 5 < 4 < 6
    should be false

  4. #4
    Use this: dudeomanodude's Avatar
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    I would imagine the easiest way is to place these numbers in a list or vector, and traverse it checking if prev < curr.

    If you make it to the end of the list, the order is correct.
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    sorry I must have had a brain fart ...
    Code:
    a < b && b < c && c < d
    etc...


    my post probably wasn't clear, I was just looking for that

    .... I should probably take a break
    Last edited by Marksman; 02-27-2008 at 09:19 PM.

  6. #6
    Use this: dudeomanodude's Avatar
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    Quote Originally Posted by Marksman View Post
    sorry I must have had a brain fart ...
    Code:
    a < b && b < c && c < d
    etc...
    Well sure that will work for just four numbers, but what if you have 50 numbers? Will you write out all those comparison tests?
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    Yeah that's true. In my actual program I only had 4 variables, so it was manageable.
    Otherwise the vector/list approach would definitely be better.

  8. #8
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    How are the numbers stored? In a list/array/vector of some kind? You can potentially keep track if the values are ordered as they are entered and simply have a flag (initialized to true for the empty container). Whenever you add a new number, simply check if it is more than the previous value - if not then set the flag to false meaning the list is not ordered. When you do your if test, then just check this flag (an O(1) operation).
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