infinite loop

[jhonny1677]

Write your question here.
on executing the program it goes to infinite loop,where should i make correction with respect to my program?

  #include<iostream.h>
class matrix
{
   int m[10][10];
   int r;
   int c;
   public:
   void display();
   void input();
   int getr()
{
  return(r);
}
int getc()
{
 return(c);
}

   matrix add(matrix m2);
   matrix sub(matrix m2);
   matrix mul(matrix m1,matrix m2);
   matrix tps();
};
void matrix::input()
{
  cout<<"\n enter dimensions";
  cin>>r>>c;
  for(int i=0;i<r;i++)
  for(int j=0;j<c;j++)
  cin>>m[i][j];

}
void matrix::display()
{
   for(int i=0;i<r;i++)
   {
     cout<<"\n";
     for(int j=0;j<c;j++)
     cout<<m[i][j]<<"\t";
   }
}
matrix matrix::add(matrix m2)
{
  matrix m3;

 for(int i=0;i<m2.getr();i++)

 for(int j=0;j<m2.getc();j++)
    {
       m3.m[i][j]=m[i][j]+m2.m[i][j];
    }

     return(m3);
}
matrix matrix::sub(matrix m2)
{
  matrix m3;

     for(int i=0;i<m2.getr();i++)
     for(int j=0;j<m2.getc();j++)
      {
	m3.m[i][j]=m[i][j]-m2.m[i][j];
      }
	return (m3);
}
matrix matrix::mul(matrix m1,matrix m2)
{
  matrix m3;
  m3.r=m1.r;
  m3.c=m2.c;
   {

     for(int i=0;i<m3.getr();i++)
     for(int j=0;j<m3.getc();j++)
      {
	 m3.m[i][j]=0;
	 for(int k=0;k<=m3.getc();k++)
	 m3.m[i][j]=m3.m[i][j]+m[i][k]*m2.m[k][j];
      }

    }

    return(m3);
}
matrix matrix::tps()
{
  matrix m3;
  for(int i=0;i<c;i++)
  for(int j=0;j<r;j++)
     m3.m[i][j]=m[j][i];

   return m3;
}

void main()
{
  matrix m1,m2,m3,m4,m5,m6,m7,m8;
  int ch;
  cout<<"\n enter information for first matrix";
  m1.input();
  cout<<"\n first matrix is";
  m1.display();
  cout<<"\n enter information for second matrix";
  m2.input();
  cout<<"\n seond matrix is";
  m2.display();
  if( m1.getr()==m2.getr() && m1.getc()==m2.getc())
  cout<<"\n menu";
  cout<<" \n press 1 for addition";
  cout<<"\n press 2 for multiplication";
  cout<<"\n press 3 for subtraction";
  cout<<"\n press 4 for transpose";
  cout<<"enter your choice";
  cin>>ch;
  switch(ch)

{ case 1:
  m3=m1.add(m2);
  cout<<"\n sum of two matrices is";
  m3.display();
  break;
  case 2:
  m4=m1.sub(m2);
  cout<<"\n difference of two matrices is";
  m4.display();
  break;
  case 3:
  m5=m8.mul(m1,m2);
  cout<<"\n product of two matrices is";
  m5.display();
  break;
  case 4:
  m6=m1.tps();
  cout<<"\n transpose of first matrix is";
  m6.display();
  m7=m2.tps();
  cout<<"\n transpose of second matrix is";
  m7.display();
  break;
  deafault:cout<<"invalid choice";
  break;
}
}

[Lachlan Easton]

How do you know you're getting an infinite loop? When is the application stopping?

[jhonny1677]

Run it...application not stopping

[Mats]

Could you enlighten us with some more information? Where exactly does the program not stop?

Also, <iostream.h> is depreciated; use <iostream> instead. void main() is not even legal C++. It must always be int main(). I strongly suggest you update your compiler if it's letting this compile, as it means your compiler is not even compliant with standards set over a decade ago.

[NVTKrishna]

Member variables 'r' and 'c' are not initialized for matrix "m3" in "add", "sub"
and "tps" funtions.

Corrected funtions

matrix matrix::add(matrix m2)
{
 matrix m3;
 m3.r=r;
 m3.c=c;

 for(int i=0;i<m2.getr();i++)

 for(int j=0;j<m2.getc();j++)
    {
       m3.m[i][j]=m[i][j]+m2.m[i][j];
    }

     return(m3);
}

matrix matrix::sub(matrix m2)
{
  matrix m3;
  m3.r=r;
  m3.c=c;

     for(int i=0;i<m2.getr();i++)
     for(int j=0;j<m2.getc();j++)
      {
	m3.m[i][j]=m[i][j]-m2.m[i][j];
      }
	return (m3);
}

matrix matrix::tps()
{
  matrix m3;
  m3.r=c;
  m3.c=r;

  for(int i=0;i<c;i++)
  for(int j=0;j<r;j++)
     m3.m[i][j]=m[j][i];

   return m3;
}

To avoid this type of problems, always initialize the member variables in the constructor to suitable values.