C++ matrix operations?

I am writing a program to do simple matrix operations. but i want the dimensions of the matrix to be fed by the user. the code below, gives the following error during compile time...





`cols' cannot appear in a constant-expression





cout %26lt;%26lt; "Number of rows:";


int r;


cin %26gt;%26gt; r;


cout %26lt;%26lt; "Number of columns:";


int c;


cin %26gt;%26gt; c;





const int rows=r;


const int cols=c;





// Assign dimensions


float* mat1[rows][cols]; float* mat2[rows][cols]; float* mat3[rows][cols];





mat1= new float [rows][cols];


mat2= new float [rows][cols];


mat3= new float [rows][cols];





it works fine if they are 1 dimensional arrays, so why doesnt it compile if i use 2 dimensions. please help.

C++ matrix operations?
Here is how to create multidimensional arrays in C++:





typedef float* FloatArray;





int main( )


{


int rows = 0;


int columns = 0;





cout %26lt;%26lt; "Number of rows: ";


cin %26gt;%26gt; rows;


cout %26lt;%26lt; "Number of columns: ";


cin %26gt;%26gt; columns;





FloatArray *mat1 = new FloatArray[rows];


FloatArray *mat2 = new FloatArray[rows];


FloatArray *mat3 = new FloatArray[rows];





for(int i = 0; i %26lt; rows; i++)


{


mat1 = new float[columns];


mat2 = new float[columns];


mat3 = new float[columns];


}





return 0;


}





// To initialize or assign a value to any of the arrays' cells do the following:





mat1[rowNumber][columnNumber] = someValue;





By the way, don't forget to delete the dynamic arrays after you are done with them. Here is how to do that:





for(int i = 0; i %26lt; rows; i++)


{


delete[ ] mat1[i];


}


delete[ ] mat1;





I hope this helps!!
Reply:the reason it doesn't work is simply because you can't allocate a two dimension array that way it works for one dimension also you could have just wrote that code in one line not that it matters





float * mat1 = new float[rows][cols];





sorry couldn't give you a better help just still don't under C++ that well yet

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