Using variables for array dimensions

I have been away from c++ programming, and decided to start out by making a program that:

a) Accepts input to create a matrix (in form of an array)

b) Puts the matrix in row-echelon form

c) Solves the matrix using backwards substitution

Here is the code with errors when initializing the array:

Code:

`#include <iostream.h>`

int main()

{

int width = 1;

int height = 1;

cout<<"Enter the number of columns in the augmented matrix: ";

cin>>height;

width = height + 1;

int matrix[width][height];

return 0;

}