will vector grow dynamically

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C++

MFC

C++11

stl vector will grow dynamically by it self automatically

CArray in mfc will not ? as vector has SetAtGrow

Posted 3-Nov-15 21:40pm

imran.prdc

Updated 3-Nov-15 22:01pm

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Iain Clarke, Warrior Programmer · Accepted Answer · 2015-11-03T22:08:00

Solution 1

Yes and No.

If you do:

std::vector<int> V;
V[7] = 123;
</int>

it will crash. Well, it will give you nice errors in debug.
But you can do:

V.push_back (1234);

and V will grow appropriately.

That's pretty similar with CArray as well.

I hope that helps,

Iain.

Posted 3-Nov-15 22:08pm

Iain Clarke, Warrior Programmer

CPallini · Accepted Answer · 2015-11-03T22:11:00

Solution 2

The very first sentence in the documentation[^]:

Supports arrays that are like C arrays, but can dynamically reduce and grow as necessary.

Posted 3-Nov-15 22:11pm

CPallini

Comments

[no name] 4-Nov-15 4:50am

CArray<cpoint, cpoint=""> ptArray;
ptArray.Add(CPoint(10, 20)); // Element 0
ptArray.Add(CPoint(30, 40)); // Element 1
// Element 2 deliberately skipped
ptArray.SetAtGrow(5, CPoint(50, 60)); // Element 3

std::vector<cpoint> m_Points1;
m_Points1.emplace_back(CPoint(10,20));
m_Points1.emplace_back(CPoint(20, 30));

m_Points1.resize(5, CPoint(50, 60)); // Element 3

here in this case SetAtGrow is fixing the value at 5 position
but vector is doing for 3 , 4 ,5 can let me know what s the problem

CPallini 4-Nov-15 5:37am

There is no problem. It is just a semantic difference between std::vector and CArray.