Using Vectors

This is a discussion on Using Vectors within the C++ Programming forums, part of the General Programming Boards category; I am currently working on vectors and I understand them but I would understand them better if I knew where ...

  1. #1
    Registered User
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    Jan 2006

    Using Vectors

    I am currently working on vectors and I understand them but I would understand them better if I knew where in a program they would be used.

  2. #2
    Join Date
    Jan 2002
    Anywhere you'd normally use an array.
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  3. #3
    Registered User
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    Jan 2005
    Especially if you don't know how much space you'll need.

  4. #4
    Registered User
    Join Date
    Apr 2005
    and also if you don't know the size of a data container...

    #include <iostream>
    #include <vector>     // a must for vector use
    using namespace std;
    int main()
         vector<int> iVector;   // you have to specify the vector type by a class or a structure
         int answer;
         int temp;
         cout<<"How many numbers do you want to enter? ";
         for(int i=0; i < answer; i++)
              cout<<answer<<" Enter a number: ";     // display how many numbers the user has left to enter
    // this is magic... the temporary integer is pushed onto the back of the vector...and given a location in that vector, which you can access using iVector[anumber]
    i prefer using vectors over arrays any day...
    Only thing I hate doin, though, is that to access an object of a vector class (ex. iVector.erase()) you have to create a vector iterator that points to a location in the vector

    class aClass
              int number;
    aClass theClass;
    vector<aClass> theClassV;
    vector<aClass>::iterator theClassVIterator;
    for(int i=0;i<=3;i++)
    //                                                          0             1               2
    // so now theClassV vector holds {theClass, theClass, theClass}
    // at the storage spaces 0, 1, 2
    // If i wanted to delete what was at location 1 I would have to do this...
    this is the only way ive found how to make the iterator the position of the vector you want...there probably is a pro somewhere around here who can be sure...
    Last edited by gL_nEwB; 05-17-2006 at 04:25 PM.

  5. #5
    C++ Witch laserlight's Avatar
    Join Date
    Oct 2003
    Um, gL_nEwB, despite the name, theClassVIterator is a vector<aClass>.
    Assuming such an element exists, if you wanted to delete the element at 'location 1', you would use:
    theClassV.erase(theClassV.begin() + 1);
    Quote Originally Posted by Bjarne Stroustrup (2000-10-14)
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