pointer matrix error on execution - c++

Question

class Matrix{
double **val;
int rows,cols,errorCode;
public:
Matrix();
Matrix(int);
Matrix(int, int);
~Matrix();
void Print();
void Read();
double Get(int, int);
void Assign(int,int,double);
void Addition(Matrix&);
void Subtraction(Matrix&);
Matrix Multiply(Matrix&);
void Multiply(double);
};
Matrix::Matrix(){
//First array go with rows.
val = new double*[1];
val[1] = new double[1];
rows = 1;
cols = 1;
errorCode = 0;
}
Matrix::Matrix(int n){
rows = n;
cols = n;
val = new double*[rows];
for(int i = 0;i<rows;i++){
val[i] = new double[cols];
}
}
Matrix::Matrix(int n,int m){
rows = n;
cols = m;
val = new double*[rows];
for(int i = 0;i<rows;i++){
val[i] = new double[cols];
}
}
Matrix::~Matrix(){
for(int i=0;i<rows;i++){
delete[] val[i];
}
delete[] val;
}
Matrix Matrix::Multiply(Matrix &a){
if(cols != a.rows){
Matrix b;
b.errorCode=111; //That means dimensions are not valid;
return b;
}
else{
Matrix b(rows,a.cols);
double p;
for(int i=0;i<rows;i++){
for(int j=0;j<a.cols;j++){
p=0;
for(int k=0;k<cols;k++){p += val[i][k]*a.val[k][j];}
b.Assign(i,j,p);
}
}
return b;
}
}
When i compile it seems to be ok, but when i run it doesn't work and i don't understand why...it says "program stoped worked" and returned error 255
If needed i can put all the code i write...
I added constructors...
unfutunatly i can not post images... it says process returned 255, and here is an alert from windows that the program was not working corectly and it stoped working...
Here is all the code if someone have time and if it helps you to understand better..
#include <iostream>
using namespace std;
class Matrix{
double **val;
int rows,cols,errorCode;
public:
Matrix();
Matrix(int);
Matrix(int, int);
~Matrix();
void Print();
void Read();
double Get(int, int);
void Assign(int,int,double);
void Addition(Matrix&);
void Subtraction(Matrix&);
Matrix Multiply(Matrix&);
void Multiply(double);
};
Matrix::Matrix(){
//First array go with rows.
val = new double*[1];
val[0] = new double[1];
rows = 1;
cols = 1;
errorCode = 0;
}
Matrix::Matrix(int n){
rows = n;
cols = n;
val = new double*[rows];
for(int i = 0;i<rows;i++){
val[i] = new double[cols];
}
}
Matrix::Matrix(int n,int m){
rows = n;
cols = m;
val = new double*[rows];
for(int i = 0;i<rows;i++){
val[i] = new double[cols];
}
}
Matrix::~Matrix(){
for(int i=0;i<rows;i++){
delete[] val[i];
}
delete[] val;
}
void Matrix::Read(){
for(int i=0;i<rows;i++){
delete[] val[i];
}
delete[] val;
cout<<"Give the matrix dimensions (rows and cols) : ";
cin>>rows>>cols;
val = new double*[rows];
for(int i = 0;i<rows;i++){
val[i] = new double[cols];
}
cout<<"Give the matrix values: "<<endl;
for(int i = 0;i<rows;i++){
for(int j = 0;j<cols;j++){ cin>>val[i][j];}
}
}
void Matrix::Print(){
cout<<"The matrix with "<<rows<<" rows and "<<cols<<" cols, have next values: "<<endl;
for(int i = 0;i<rows;i++){
for(int j = 0;j<cols;j++){ cout<<val[i][j]<<" ";}
cout<<endl;
}
}
double Matrix::Get(int n, int m){
return val[n-1][m-1];
}
void Matrix::Assign(int n,int m,double v){
val[n-1][m-1] = v;
}
void Matrix::Addition(Matrix &a){
if(rows != a.rows || cols !=a.cols){
errorCode=111; //That means dimensions are not equal;
}
else{
for(int i = 0;i<rows;i++){
for(int j = 0;j<cols;j++){ val[i][j] += a.val[i][j];}
}
}
}
void Matrix::Subtraction(Matrix &a){
if(rows != a.rows || cols !=a.cols){
errorCode=111; //That means dimensions are not equal;
}
else{
for(int i = 0;i<rows;i++){
for(int j = 0;j<cols;j++){ val[i][j] -=a.val[i][j];}
}
}
}
void Matrix::Multiply(double x){
for(int i = 0;i<rows;i++){
for(int j = 0;j<cols;j++){ val[i][j] *= x;}
}
}
Matrix Matrix::Multiply(Matrix &a){
if(cols != a.rows){
errorCode=111; //That means dimensions are not equal;
Matrix b;
return b;
}
else{
Matrix b(rows,a.cols);
double p;
for(int i=0;i<rows;i++){
for(int j=0;j<a.cols;j++){
p=0;
for(int k=0;k<cols;k++){p += val[i][k]*a.val[k][j];}
b.Assign(i,j,p);
}
}
return b;
}
}
int main(){
Matrix a,b(2,3);
b.Assign(1,1,0);
b.Assign(1,2,3);
b.Assign(1,3,5);
b.Assign(2,1,5);
b.Assign(2,2,5);
b.Assign(2,3,2);
b.Print();
a.Read();
a.Print();
cout<<endl;
//when i read a i put 3x2 matrix, so the multiplying can be done.
Matrix c=a.Multiply(b);
c.Print();
return 0;
}
problem appear when i try to use function: Matrix Multiply(Matrix&).

Answer 1

There's an error in your default constructor:
val = new double*[1];
val[1] = new double[1];
1 is not a valid index for val, this should be:
val[0] = new double[1];