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execution error when input matrix .using multi-level pointers

xuanvinhtd (1)
thank everyone!!
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#include<stdio.h>
#include<conio.h>
#include<iostream>
#include<stdlib.h>
using namespace std;
class Matrix
     {
	 private:
		 int Sodong,Socot;
		 int **a;
	 public:
		 Matrix();
		 ~Matrix();
		 void Nhap();
		 void Xuat();
		 Matrix(const Matrix &);
		 void Tong(const Matrix &);
		 void Tich(const Matrix &);
    };
Matrix::Matrix()
{
	Sodong=0;Socot=0;
	a = NULL;
}
Matrix::Matrix(const Matrix  &b)
{
		for(int i= 0;i<Sodong;++i)
			for(int j=0;j<Socot;++j)
				a[i][j]=b.a[i][j];

}
Matrix::~Matrix()
{
	if(a)
	{
		for(int i=0;i<Socot;++i)
		{
			if(a[i]) 
				delete []a[i];
		}
		   delete []a;
	}
}

void Matrix::Nhap()
{
	int i,j;
	do
	{
		cout<<"\nNhap so dong cua Matrix :";
		cin>>Sodong;
	}while(Sodong<1);
	do
	{
		cout<<"\n Nhap so Cot cua Matrix :";
		cin>>Socot;
	}while(Socot<1);
	a=new int*[Sodong];
	if(a==NULL)
	{
		cout<<"\n Khong du bo nho !!";
		return;
	}
	for(i=0;i<Socot;++i)
	{
		a[i]= new int[Socot];
		if(a[i]==NULL)
		{
			cout<<"\n Khong du bo nho !!!";
			return;
		}
	}
	for( i=0;i<Sodong;++i)
		{
		     for( j=0;j<Socot;++j)
		       {
		         	cout<<"\n nhap a["<<i<<","<<j<<"]=";
			        cin>>a[i][j];
					
		       }
		}
}
void Matrix::Xuat()
{
	cout<<"\n Matrix :\n";
	for(int i=0;i<Sodong;++i)
	{
	     for(int j=0;j<Socot;++j)
		 cout<<"   "<<a[i][j];
	     cout<<"\n";
	}
}
void Matrix::Tong(const Matrix &b)
{
	int i,j;
	Matrix kq;
	if((this->Sodong!=b.Sodong)||(this->Socot!=b.Socot))
	{
		cout<<"\n khong cong duoc !!";
		return;
	}
	else
	{
	kq.Sodong=Sodong;
	kq.Socot=Socot;
	kq.a=new int*[Sodong];
	for( i=0;i<Socot;++i)
		(kq.a[i])=new int[Socot];
	for( i=0;i<Sodong;++i)
		for( j=0;j<Socot;++j)
		   kq.a[i][j]=this->a[i][j]+b.a[i][j];
	}
	cout<<"\n tong hai ma tran : ";
	kq.Xuat();
}
void Matrix::Tich(const Matrix &b)
{
	int i,j,k;
	Matrix kq;
	if(this->Socot!=b.Sodong)
	{
		cout<<"\n khong nhan duoc !!";
		return;
	}
	else
	{
	kq.Sodong=Sodong;
	kq.Socot=b.Socot;
	kq.a=new int*[Sodong];
	for(i=0;i<kq.Socot;++i)
		kq.a[i]=new int[Socot];
	for(j=0;j<kq.Sodong;++j)
		for(i=0;i<kq.Socot;++i)
		   {
			   kq.a[i][j]=0;
			   for(k=0;k<b.Socot;++k)
				   kq.a[i][j]+=(this->a[j][k])*(b.a[k][i]);
		   }
	}
		cout<<"\n tich hai ma tran : ";
		kq.Xuat();
}
void main()
{
	Matrix a,b;
	a.Nhap();
	b.Nhap();
	a.Xuat();
	b.Xuat();
	a.Tong(b);
	a.Tich(b);
	getch();
}
TheIdeasMan (6817)
Main should be like this:

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voidint  main()
{
	Matrix a,b;
	a.Nhap();
	b.Nhap();
	a.Xuat();
	b.Xuat();
	a.Tong(b);
	a.Tich(b);
	getch();


return 0;
}


Does the code compile? If not, post the compiler output.

IF the program runs, then try using the debugger - should be easy if there is one in your IDE.

If the debugger is too hard, then you will have to resort to putting lots of cout statements, so you can check the values of variables.

I am sorry I am not offering any other advice, but using the debugger is by far the easiest way to solve this sort of problem. There a lots of others much smarter than me that might be able to see the problem directly.

Good Luck
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