enum declaration~

This is a discussion on enum declaration~ within the C++ Programming forums, part of the General Programming Boards category; Howdy~~ I get used to declaring everthing in 2 lines such as follows: #include <iostream> void main() { enum pet; ...

  1. #1
    flashing vampire black's Avatar
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    Question enum declaration~

    Howdy~~

    I get used to declaring everthing in 2 lines such as follows:

    #include <iostream>

    void main()
    {
    enum pet;
    pet={dog,cat,bird,crocodile};
    // I heard someone was fond of crocodile, aha~
    pet myPet=dog;
    cout << myPet << endl;
    }

    but the output report an error. it works fine when I rewrite the code like this:

    #include <iostream>

    void main()
    {
    enum pet{dog,cat,bird,crocodile};
    pet myPet=dog;
    cout << myPet << endl;
    }

    why couldnt we delare it in 2 different lines as before ???
    Never end on learning~

  2. #2
    Banned frenchfry164's Avatar
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    well it looks like it's written correctly, except myPet isn't declared. What exactly does the compiler tell you when you try to compile that?

    I don't think you should declare an enum inside of a function anyway.

    PS: I've never seen anyone do that first method anyway.

  3. #3
    flashing vampire black's Avatar
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    Originally posted by frenchfry164
    I don't think you should declare an enum inside of a function anyway.
    then what should it be ?
    Never end on learning~

  4. #4
    Guest Sebastiani's Avatar
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    I don't think you should declare an enum inside of a function anyway.
    That is just flat wrong. The whole point of having enum's is to 'clean-up' the interface of the code. So when faced with the question - USE THEM! ( inside or outside of functions... )



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  5. #5
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    enumerations can only be declared using the second method. Essentially, you're enum is a type, not a variable. That's why you can't assign values to it, you have to define it's contents before it's used.

    And by the way, delcaring everything in two lines is a bad thing. Initialise your variables with the values you want if you can.

    Why?

    Coz if you do this:

    int i = 0;

    then i's constructor receives 0 as a parameter and it's initialised with that value.

    if you do this:

    int i;
    i = 0;

    i is constructed, and after that happens the assignment operator is called for i, so instead of just one function, there's two being called.

    So, if you can, use the first method, not the second.

    U.
    Quidquid latine dictum sit, altum sonatur.
    Whatever is said in Latin sounds profound.

  6. #6
    flashing vampire black's Avatar
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    Question

    Originally posted by Uraldor

    Coz if you do this:

    int i = 0;

    then i's constructor receives 0 as a parameter and it's initialised with that value.

    if you do this:

    int i;
    i = 0;

    i is constructed, and after that happens the assignment operator is called for i, so instead of just one function, there's two being called.

    So, if you can, use the first method, not the second.

    U.
    but......it seems nothing serious happens if I declare a variable in 2 lines. does it cause any unexpected errors ?

    PS: please forgive my poor comprehension Caz' I am fresh to C++.
    Never end on learning~

  7. #7
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    it seems nothing serious happens if I declare a variable in 2 lines

    you dont declare variables in two lines. One line you declare it, another line you store things in it.

    does it cause any unexpected errors ?

    absolutely not, why would it? I'm just trying to tell you that declaring in one line, and storing in another is twice as intensive processor-wise as declaring and storing on the same line.

    If you do it in the one statement, then the value gets stored during construction.
    Quidquid latine dictum sit, altum sonatur.
    Whatever is said in Latin sounds profound.

  8. #8
    flashing vampire black's Avatar
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    thanx Uraldor~

    And I still wanna know whether those which are not simply data types should only be delclared in 1 line as I tested enum before ?
    Never end on learning~

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