Creating a function that sorts strings by alphabetic order?

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  1. #1
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    Creating a function that sorts strings by alphabetic order?

    Any good example of how it's done?

  2. #2
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    I'm sure there are some on the board, for those willing to search....
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    std::string has < and > operators, so I believe the std::sort() function should work. If you want to sort without regards to case, that's another story.

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    Quote Originally Posted by cpjust View Post
    std::string has < and > operators, so I believe the std::sort() function should work. If you want to sort without regards to case, that's another story.
    Sure, but I want to create the function. Not use one that already exists, for educational purposes.

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    So, implement one of the following:
    Bubble-sort
    Merge-sort
    Quick-sort

    These are googleable, so there's no point in us repeating in less clear form what you can find in for example Wikipedia.

    Sorting strings or numbers or anything else is equivalent if you have a compare operation that can compare two elements of the type you are sorting.

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  6. #6
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    Creating your own version of sort() is pretty simple, especially now that you know std::strings can be compared with < or > or == operators.

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    Quote Originally Posted by matsp View Post
    So, implement one of the following:
    Bubble-sort
    Merge-sort
    Quick-sort

    These are googleable, so there's no point in us repeating in less clear form what you can find in for example Wikipedia.

    Sorting strings or numbers or anything else is equivalent if you have a compare operation that can compare two elements of the type you are sorting.

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    Isnt it like in maths, that for example 1>2. But how can you compare A and B? A>B?

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    Quote Originally Posted by Glauber View Post
    Isnt it like in maths, that for example 1>2. But how can you compare A and B? A>B?
    Depends on the object. For strings, A>B is true only if A is lexically greater; that is if A would be found later in the dictionary than B. (assuming that dictionary considers uppercase letters greater then lower case)

    For a truly generic interface, the best way to do it is to have a special comparator function/function object, that is passed as an argument to the sorting function. That way you sorting algorithm can be used to sort the same list of objects by different criteria.
    It is too clear and so it is hard to see.
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    Quote Originally Posted by King Mir View Post
    Depends on the object. For strings, A>B is true only if A is lexically greater; that is if A would be found later in the dictionary than B. (assuming that dictionary considers uppercase letters greater then lower case)

    For a truly generic interface, the best way to do it is to have a special comparator function/function object, that is passed as an argument to the sorting function. That way you sorting algorithm can be used to sort the same list of objects by different criteria.
    Do you have any examples of an "easy" function to sort strings?

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    Bubble sort is easy. There's nothing special about sorting strings.
    It is too clear and so it is hard to see.
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    Here's a tip for you;


    string woot = "blabla"

    woot.at(0) == "b"
    woot.at(1) == "l"
    woot.at(2) == "a"
    woot.at(n) == ...

    char letterz = char(woot.at(0)) == 'b'

    basically...

    int somenumber = int(letterz) == 62

    ... c = 63, d = 64 ...


    gl and hf with algorithms ;D
    Last edited by simpleid; 05-27-2008 at 04:30 PM.

  12. #12
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    Quote Originally Posted by simpleid View Post
    Here's a tip for you;


    string woot = "blabla"

    woot.at(0) == "b"
    woot.at(1) == "l"
    woot.at(2) == "a"
    woot.at(n) == ...

    char letterz = char(woot.at(0)) == 'b'

    basically...

    int somenumber = int(letterz) == 62

    ... c = 63, d = 64 ...


    gl and hf with algorithms ;D
    What if the string is unknown to the program before the input?
    Is there an easier way of sorting strings?

  13. #13
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    Can you write a sort for sorting an array of int's? Because std::string supports all the same comparison operators (< > etc), the only thing different is the type of the variables...
    I might be wrong.

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    Need another example.

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