Multi-Dimensional Vector

I'm having trouble outputting a multi-dimensional vector that has specific values.

Code:

---

void DisplayVect (const vector<vector<int> >& v);

int main(){

        const int Max = 7;

        vector<vector<int> > v(8,5);

        DisplayVect(v);

        system("Pause");

}

void DisplayVect (const vector<vector<int> >& v)
{  for (int i = 0; i < v.size(); i++)      // loops through each row of v
  {  for (int j = 0; j < v[i].size(); j++) // loops through each element of each row
          cout << v[i][j] << " ";          // prints the jth element of the ith row
      cout << endl;
  }
}

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That code above works fine, but as far as assigning values, this code will add on to the vector of 0's with values from 0 to 6, instead of changing the values that are already printed.

Code:

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for(int i = 0; i < Max; i++){
        for(int j = 0; j < Max; j++){
                v[i].push_back(j);
        }
        }

---

Thanks for your help.

You are using the push_back() member function which was designed precisely to add on one more element to the container.

push_back() adds new elements onto the vector. You should use assignment and subscripting like you did in the first loop:

Code:

---

void ResetVect (const vector<vector<int> >& v)
{  for (int i = 0; i < v.size(); i++)      // loops through each row of v
  {  for (int j = 0; j < v[i].size(); j++) // loops through each element of each row
          v[i][j] = 0;
  }
}

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Thanks, that makes sense about the push_back() part.

One problem with the code, in the ResetVect() function, an error occurs when v[i][j] = 0:
error C3892: 'j' : you cannot assign to a variable that is const
I'm not too sure why that is occurring.

Code:

---

void DisplayVect (const vector<vector<int> >& v);
void ResetVect (const vector<vector<int> >& v);


int main(){

        const int Max = 8;

        vector<vector<int> > v(8,5);

       
        ResetVect(v);
        DisplayVect(v);
       


        system("Pause");

}

void DisplayVect (const vector<vector<int> >& v)
{  for (int i = 0; i < v.size(); i++)      // loops through each row of v
  {  for (int j = 0; j < v[i].size(); j++) // loops through each element of each row
          cout << v[i][j] << " ";          // prints the jth element of the ith row
      cout << endl;
  }
}

void ResetVect (const vector<vector<int> >& v)
{  for (int i = 0; i < v.size(); i++)      // loops through each row of v
  {  for (int j = 0; j < v[i].size(); j++) // loops through each element of each row
          v[i][j] = 0;
  }
}

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If you are modifying the vector, the parameter should not be a reference to const, it should just be a reference.

I'm still having some trouble with the program; it will output a 5x8 vector of 0's but that's about it.

What am I missing in my code so that the values in each row will go from 0 to 4?

What is your updated code snippet?

Forgot about that:

Code:

---

...
void DisplayVect (vector<vector<int> >& v);
void ResetVect (vector<vector<int> >& v);


int main(){

        vector<vector<int> > v(8,5);


       
        ResetVect(v);
        DisplayVect(v);
       


        system("Pause");

}

void DisplayVect (vector<vector<int> >& v)
{ 
        for (int i = 0; i < v.size(); i++){      // loops through each row of v
          for (int j = 0; j < v[i].size(); j++){ // loops through each element of each row
              cout << v[i][j] << " ";                        // prints the jth element of the ith row
          }
        cout << endl;
  }
}

void ResetVect (vector<vector<int> >& v)
{ 
        for (int i = 0; i < v.size(); i++){      // loops through each row of v
                for (int j = 0; j < v[i].size(); j++){ // loops through each element of each row
          v[i][j] = 0;
                }
  }
}

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Well, it seems to me that you need to add another function along the lines of ResetVect() to perform this special assignment of numbers for you.

Quote:

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Originally Posted by Kramer55

I'm still having some trouble with the program; it will output a 5x8 vector of 0's but that's about it.

What am I missing in my code so that the values in each row will go from 0 to 4?

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I'm mot shure that I understood the question ( because the answer is so obvious ).

Code:

---

void ResetVect (vector<vector<int> >& v)
{ 
        for (int i = 0; i < v.size(); i++){      // loops through each row of v
                for (int j = 0; j < v[i].size(); j++){ // loops through each element of each row
                          v[i][j] = j;
                }
          }
}

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Kurt