c++ Trying to delete last row and column of a 2d array
0
I am trying to delete last row and the last column of a 2d array. I created this method for this purpose.
void deleteLastRowColumn(int **A, int row, int column)
{
int **temp = A;
A = new int *[row - 1];
for (int i = 0; i < row - 1; i++)
{
A[i] = new int[column - 1];
for (int j = 0; j < column - 1; j++)
{
A[i][j] = temp[i][j];
}
delete temp[i];
}
}
and printing the result with
void printArray(int **a, int row, int column)
{
for (int i = 0; i < row; i++)
{
for (int j = 0; j < column; j++)
{
cout << a[i][j] << " ";
}
cout << endl;
}
}
And my main method creates a 5x5 array
int main()
{
int **a;
a = new int *[5];
for (int i = 0; i < 5; i++)
a[i] = new int[5];
for(int i = 0; i < 5; i++)
{
for(int j = 0; j < 5; j++)
{
a[i][j] = (i*5) + j + 1;
}
}
printArray(a, 5, 5);
cout << "nnnn";
deleteLastRowColumn(a,5,5);
printArray(a,4,4);
}
The output didn't make sense to me:
1 2 3 4 5
6 7 8 9 10
11 12 13 14 15
16 17 18 19 20
21 22 23 24 25
6 7 8 9
11 12 13 14
16 17 18 19
0 0 18 19
I expected it to remove last column and last row but something different happened. If you can explain me what's wrong here that would be great!
Thank you.
c++ arrays dynamic-arrays
asked Nov 22 '18 at 13:53
burakokumusburakokumus
41
add a comment |
0
I am trying to delete last row and the last column of a 2d array. I created this method for this purpose.
void deleteLastRowColumn(int **A, int row, int column)
{
int **temp = A;
A = new int *[row - 1];
for (int i = 0; i < row - 1; i++)
{
A[i] = new int[column - 1];
for (int j = 0; j < column - 1; j++)
{
A[i][j] = temp[i][j];
}
delete temp[i];
}
}
and printing the result with
void printArray(int **a, int row, int column)
{
for (int i = 0; i < row; i++)
{
for (int j = 0; j < column; j++)
{
cout << a[i][j] << " ";
}
cout << endl;
}
}
And my main method creates a 5x5 array
int main()
{
int **a;
a = new int *[5];
for (int i = 0; i < 5; i++)
a[i] = new int[5];
for(int i = 0; i < 5; i++)
{
for(int j = 0; j < 5; j++)
{
a[i][j] = (i*5) + j + 1;
}
}
printArray(a, 5, 5);
cout << "nnnn";
deleteLastRowColumn(a,5,5);
printArray(a,4,4);
}
The output didn't make sense to me:
1 2 3 4 5
6 7 8 9 10
11 12 13 14 15
16 17 18 19 20
21 22 23 24 25
6 7 8 9
11 12 13 14
16 17 18 19
0 0 18 19
I expected it to remove last column and last row but something different happened. If you can explain me what's wrong here that would be great!
Thank you.
c++ arrays dynamic-arrays
asked Nov 22 '18 at 13:53
burakokumusburakokumus
41
1
Are you willing to switch from pointers tostd::vector?
– Micha Wiedenmann
Nov 22 '18 at 13:56
4
If you want to changeAindeleteLastRowColumn- pass it by reference.
– Algirdas Preidžius
Nov 22 '18 at 13:56
@MichaWiedenmann I wish I could. The course I'm taking doesn't let me...
– burakokumus
Nov 22 '18 at 14:03
@burakokumus: That is a problem in your course. You can only change*A, notA, so you cannot resize both dimensions. Therefore,Aremains a(int*)[5], The best you can do is to setA[0]toA[3]toint[4]andA[4]tonullptr.
– MSalters
Nov 22 '18 at 14:08
I made the change proposed by Algirdas Preidzius and test it, it works. Just add adelete tempat the end of the function, but it was not the cause of the problem
– Damien
Nov 22 '18 at 15:13
add a comment |
0
0
0
I am trying to delete last row and the last column of a 2d array. I created this method for this purpose.
void deleteLastRowColumn(int **A, int row, int column)
{
int **temp = A;
A = new int *[row - 1];
for (int i = 0; i < row - 1; i++)
{
A[i] = new int[column - 1];
for (int j = 0; j < column - 1; j++)
{
A[i][j] = temp[i][j];
}
delete temp[i];
}
}
and printing the result with
void printArray(int **a, int row, int column)
{
for (int i = 0; i < row; i++)
{
for (int j = 0; j < column; j++)
{
cout << a[i][j] << " ";
}
cout << endl;
}
}
And my main method creates a 5x5 array
int main()
{
int **a;
a = new int *[5];
for (int i = 0; i < 5; i++)
a[i] = new int[5];
for(int i = 0; i < 5; i++)
{
for(int j = 0; j < 5; j++)
{
a[i][j] = (i*5) + j + 1;
}
}
printArray(a, 5, 5);
cout << "nnnn";
deleteLastRowColumn(a,5,5);
printArray(a,4,4);
}
The output didn't make sense to me:
1 2 3 4 5
6 7 8 9 10
11 12 13 14 15
16 17 18 19 20
21 22 23 24 25
6 7 8 9
11 12 13 14
16 17 18 19
0 0 18 19
I expected it to remove last column and last row but something different happened. If you can explain me what's wrong here that would be great!
Thank you.
c++ arrays dynamic-arrays
asked Nov 22 '18 at 13:53
burakokumusburakokumus
41
I am trying to delete last row and the last column of a 2d array. I created this method for this purpose.
void deleteLastRowColumn(int **A, int row, int column)
{
int **temp = A;
A = new int *[row - 1];
for (int i = 0; i < row - 1; i++)
{
A[i] = new int[column - 1];
for (int j = 0; j < column - 1; j++)
{
A[i][j] = temp[i][j];
}
delete temp[i];
}
}
and printing the result with
void printArray(int **a, int row, int column)
{
for (int i = 0; i < row; i++)
{
for (int j = 0; j < column; j++)
{
cout << a[i][j] << " ";
}
cout << endl;
}
}
And my main method creates a 5x5 array
int main()
{
int **a;
a = new int *[5];
for (int i = 0; i < 5; i++)
a[i] = new int[5];
for(int i = 0; i < 5; i++)
{
for(int j = 0; j < 5; j++)
{
a[i][j] = (i*5) + j + 1;
}
}
printArray(a, 5, 5);
cout << "nnnn";
deleteLastRowColumn(a,5,5);
printArray(a,4,4);
}
The output didn't make sense to me:
1 2 3 4 5
6 7 8 9 10
11 12 13 14 15
16 17 18 19 20
21 22 23 24 25
6 7 8 9
11 12 13 14
16 17 18 19
0 0 18 19
I expected it to remove last column and last row but something different happened. If you can explain me what's wrong here that would be great!
Thank you.
c++ arrays dynamic-arrays
c++ arrays dynamic-arrays
asked Nov 22 '18 at 13:53
burakokumusburakokumus
41
asked Nov 22 '18 at 13:53
burakokumusburakokumus
41
asked Nov 22 '18 at 13:53
burakokumusburakokumus
41
asked Nov 22 '18 at 13:53
burakokumusburakokumus
41
asked Nov 22 '18 at 13:53
burakokumusburakokumus
41
41
1
Are you willing to switch from pointers tostd::vector?
– Micha Wiedenmann
Nov 22 '18 at 13:56
4
If you want to changeAindeleteLastRowColumn- pass it by reference.
– Algirdas Preidžius
Nov 22 '18 at 13:56
@MichaWiedenmann I wish I could. The course I'm taking doesn't let me...
– burakokumus
Nov 22 '18 at 14:03
@burakokumus: That is a problem in your course. You can only change*A, notA, so you cannot resize both dimensions. Therefore,Aremains a(int*)[5], The best you can do is to setA[0]toA[3]toint[4]andA[4]tonullptr.
– MSalters
Nov 22 '18 at 14:08
I made the change proposed by Algirdas Preidzius and test it, it works. Just add adelete tempat the end of the function, but it was not the cause of the problem
– Damien
Nov 22 '18 at 15:13
add a comment |
1
Are you willing to switch from pointers tostd::vector?
– Micha Wiedenmann
Nov 22 '18 at 13:56
4
If you want to changeAindeleteLastRowColumn- pass it by reference.
– Algirdas Preidžius
Nov 22 '18 at 13:56
@MichaWiedenmann I wish I could. The course I'm taking doesn't let me...
– burakokumus
Nov 22 '18 at 14:03
@burakokumus: That is a problem in your course. You can only change*A, notA, so you cannot resize both dimensions. Therefore,Aremains a(int*)[5], The best you can do is to setA[0]toA[3]toint[4]andA[4]tonullptr.
– MSalters
Nov 22 '18 at 14:08
I made the change proposed by Algirdas Preidzius and test it, it works. Just add adelete tempat the end of the function, but it was not the cause of the problem
– Damien
Nov 22 '18 at 15:13
1
1
Are you willing to switch from pointers to
std::vector?– Micha Wiedenmann
Nov 22 '18 at 13:56
Are you willing to switch from pointers to
std::vector?– Micha Wiedenmann
Nov 22 '18 at 13:56
4
4
If you want to change
A in deleteLastRowColumn - pass it by reference.– Algirdas Preidžius
Nov 22 '18 at 13:56
If you want to change
A in deleteLastRowColumn - pass it by reference.– Algirdas Preidžius
Nov 22 '18 at 13:56
@MichaWiedenmann I wish I could. The course I'm taking doesn't let me...
– burakokumus
Nov 22 '18 at 14:03
@MichaWiedenmann I wish I could. The course I'm taking doesn't let me...
– burakokumus
Nov 22 '18 at 14:03
@burakokumus: That is a problem in your course. You can only change
*A, not A, so you cannot resize both dimensions. Therefore, A remains a (int*)[5], The best you can do is to set A[0] to A[3] to int[4] and A[4] to nullptr.– MSalters
Nov 22 '18 at 14:08
@burakokumus: That is a problem in your course. You can only change
*A, not A, so you cannot resize both dimensions. Therefore, A remains a (int*)[5], The best you can do is to set A[0] to A[3] to int[4] and A[4] to nullptr.– MSalters
Nov 22 '18 at 14:08
I made the change proposed by Algirdas Preidzius and test it, it works. Just add a
delete tempat the end of the function, but it was not the cause of the problem– Damien
Nov 22 '18 at 15:13
I made the change proposed by Algirdas Preidzius and test it, it works. Just add a
delete tempat the end of the function, but it was not the cause of the problem– Damien
Nov 22 '18 at 15:13
add a comment |
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1
Are you willing to switch from pointers to
std::vector?– Micha Wiedenmann
Nov 22 '18 at 13:56
4
If you want to change
AindeleteLastRowColumn- pass it by reference.– Algirdas Preidžius
Nov 22 '18 at 13:56
@MichaWiedenmann I wish I could. The course I'm taking doesn't let me...
– burakokumus
Nov 22 '18 at 14:03
@burakokumus: That is a problem in your course. You can only change
*A, notA, so you cannot resize both dimensions. Therefore,Aremains a(int*)[5], The best you can do is to setA[0]toA[3]toint[4]andA[4]tonullptr.– MSalters
Nov 22 '18 at 14:08
I made the change proposed by Algirdas Preidzius and test it, it works. Just add a
delete tempat the end of the function, but it was not the cause of the problem– Damien
Nov 22 '18 at 15:13