How to use iterator to operate a two-dimensional array created by vector?

minotaurus

Define a two-dimensional array like this:
vector <vector <int>> ivec;

How should it be initialized with iterator?

firegun

for (vector <vector <int>> :: iterator iter = ivec.begin (); iter! = ivec.end (); ++ iter)
{
 for (vector <int> :: iterator iiter = (* iter) .begin (); iiter! = (* iter) .end (); ++ iiter)
 {
  * iiter = ??;
  ..........
 }
}

minotaurus

vector <int> ivec (10);
One-dimensional array can set the storage space of the array like this, what about two-dimensional?

001250200

vector <vector <int>> ivec (2);
typedef vector <int> :: iterator Iter;
typedef vector <vector <int>> :: iterator IIter;
IIter iiter;
Iter iter;
for (iiter = ivec.begin (); iiter! = ivec.end (); iiter ++)
{
(* iiter) .resize (3);
for (iter = (* iiter) .begin (); iter! = (* iiter) .end (); iter ++)
cin >> (* iter);
}

珈蓝易拉罐

vector <vector <int>> ivec;
The iterator of the first dimension points to vector <int>, and the iterator of the second dimension points to int.

boxer2005

vector <vector <int>> ivec;
-------------------------------------------------- -----------------------------------
Here you define an empty vector, which cannot be initialized with iterator, you should use push_back operation to add elements.
Alternatively, instead of defining an empty vector, you can give an initial size.

minotaurus

Also askboxer2005:
For the001250200method vector <vector <int>> ivec (2) ;, this is to define a two-dimensional two-dimensional array, but does not specify the number of columns. How should we define a two-dimensional array with specified rows and columns What about arrays?

珈蓝易拉罐

The vector specifies that the rows and columns are not significant, it can always change at any time.

珈蓝易拉罐

If the dimensional information of your data can be determined at compile time, and it will not change thereafter, then using a native array is also good.

珈蓝易拉罐

Specifying multidimensional at the beginning can be like this:

vector <vector <int>> a (3, vector <int> (4)); // Equivalent to a 3 × 4 integer array.