Inserting an element in a 2-D vector

[Raj]

I have a 2-D vector declared as vector<vector <uint> > solution(m,
vector<uint>n). I have initialized this vector with values. Now I want
to insert an element in the (i,j) position. I am trying to do
solution.insert(j, 1, value), but this gives me the error 'no
matching function for call to 'std::vector<unsigned int,
std::allocator<unsigned int> >::insert(uint&, int, int)'

How do I get this done?

Thanks,
Raj

 

[tonydee]

I have a 2-D vector declared as vector<vector <uint> > solution(m,
vector<uint>n). I have initialized this vector with values. Now I want
to insert an element in the (i,j) position. I am trying to do
solution.insert(j, 1, value), but this gives me the error 'no
matching function for call to 'std::vector<unsigned int,
std::allocator<unsigned int> >::insert(uint&, int, int)'

How do I get this done?

Thanks,
Raj

Given
iterator insert(iterator pos, const T& x)

Try
solution.insert(solution.begin() + j, value)

I trust you realise, in psuedo-code:
{1, 2, 4}.insert(begin() + 2, 3) == {1, 2, 3, 4}
whereas
{1, 2, 4}[2] = 3 == {1, 2, 3}.
The former is typically slower, as elements after the insertion point
need to be "moved over" to make space, and sometimes the array may
need to be resized and all elements copied. Only if this proves a
performance problem with your particular data set, you may want to
consider using a std::list<>....

Cheers,
Tony

 

[Raj]

Thanks for the answer. It works now!

Raj

I have a 2-D vector declared as vector<vector <uint> > solution(m,
vector<uint>n). I have initialized this vector with values. Now I want
to insert an element in the (i,j) position. I am trying to do
solution.insert(j, 1, value), but this gives me the error 'no
matching function for call to 'std::vector<unsigned int,
std::allocator<unsigned int> >::insert(uint&, int, int)'

How do I get this done?

Thanks,
Raj

Given
    iterator insert(iterator pos, const T& x)

Try
    solution.insert(solution.begin() + j, value)

I trust you realise, in psuedo-code:
     {1, 2, 4}.insert(begin() + 2, 3) == {1, 2, 3, 4}
whereas
     {1, 2, 4}[2] = 3 == {1, 2, 3}.
The former is typically slower, as elements after the insertion point
need to be "moved over" to make space, and sometimes the array may
need to be resized and all elements copied.  Only if this proves a
performance problem with your particular data set, you may want to
consider using a std::list<>....

Cheers,
Tony