Vectors of structs

This is a discussion on Vectors of structs within the C++ Programming forums, part of the General Programming Boards category; Hi, just a quick question about vectos of structs here. If I have this struct: Code: typedef struct _MyStruct { ...

  1. #1
    The superhaterodyne twomers's Avatar
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    Vectors of structs

    Hi, just a quick question about vectos of structs here. If I have this struct:


    Code:
    typedef struct _MyStruct
    {
    
    int Var1;
    int Var2;
    
    } MyStruct;

    and I have this vector:


    Code:
    vector<MyStruct> MyVectorOfStructs;

    and we'll say I did this:


    Code:
    MyStruct TempStruct;
    
    for ( int i=0; i<10; i++ ) // Just assigning values to the vector.
    {
     TempStruct.Var1=i;
     TempStruct.Var2=i;
    
     MyVectorOfStructs.push_back( TempStruct );
    }

    If I want to get MyVectorOfStructs fourth position Var1 (if you get me, it should be 5 or something), would I have to assign the fourth position of MyVectorOfStructs to a struct, and retrive the Var1 value from that, or is there a way I can directly retrive the value of the fourth position's Var1?

    Thanks.

    EDIT: I just wrote that down, didn't compile anything, so if there are errors, assume they're due to that.

  2. #2
    Devil's Advocate SlyMaelstrom's Avatar
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    Well vectors have an overloaded subscript operator so
    Code:
    MyVectorOfStructs[3].var1
    should work. And there really is no reason to typedef a struct in C++. Another option is to use an iterator, but in this case, I'd say that's pointless
    Code:
    vector<MyStruct>::iterator vecIter = MyVectorOfStructs.begin() + 3;
    
    vecIter->Var1;
    Last edited by SlyMaelstrom; 06-14-2006 at 03:22 PM.
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  3. #3
    The superhaterodyne twomers's Avatar
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    I can't believe I didn't try that. I feel like a complete idiot now!

    Sorry for waisting the space of the forum!

    I think the typedef thing is just habbit. Is there anything wrong with it in C++?

  4. #4
    semi-colon generator ChaosEngine's Avatar
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    Quote Originally Posted by twomers

    I think the typedef thing is just habbit. Is there anything wrong with it in C++?
    there's nothing especially wrong with it, it's just unnecessary. (you don't write "signed int" every time you declare an int, do you? )

    OTOH, if the struct is in a header shared between C and C++ sources, then it's actually a good thing.
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  5. #5
    The superhaterodyne twomers's Avatar
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    >> OTOH, if the struct is in a header shared between C and C++ sources, then it's actually a good thing.

    Good point. Meh, it's ... 7 letters, no biggie.

  6. #6
    erstwhile
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    There's also 'at':
    Code:
    MyVectorOfStructs.at(3).Var1;
    CProgramming FAQ
    Caution: this person may be a carrier of the misinformation virus.

  7. #7
    Devil's Advocate SlyMaelstrom's Avatar
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    (STL == options++) == true;
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  8. #8
    and the hat of wrongness Salem's Avatar
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    > I think the typedef thing is just habbit. Is there anything wrong with it in C++?
    It's automatic in C++

    So all you needed was
    Code:
    struct MyStruct
    {
    int Var1;
    int Var2;
    };
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