Program for printing the Upper and Lower triangular matrices of a square matrix (for Plus2 Students)

#include<iostream.h>
#include<conio.h>
#include<process.h>
void l_triangle(int a[30][30], int n)
{
   int i=0, j=0;
   for(i=0;i<n;i++)
   {
     for(j=0;j<n;j++)
     {
       if(i>=j)
	 cout<<a[i][j]<<" ";
       else
       cout<<" ";
     }
     cout<<"\n";
   }
}
void u_triangle(int a[30][30], int n)
{
   int i=0, j=0;
   for(i=0;i<n;i++)
   {
     for(j=0;j<n;j++)
     {
       if(i<=j)
	 cout<<a[i][j]<<" ";
       else
	 cout<<" ";
     }
     cout<<"\n";
   }
}
void main()
{
   clrscr();
   int i, j, a[30][30], r, c; char ch;
   do
   {
     cout<<"\n\nMENU\n\n";
     cout<<"1. Enter elements\n2. Display matrix"
	 <<"\n3. Display upper triangle\n4. Display lower triangle"
	 <<"\n5. Exit";
     cout<<"\nEnter your choice ";
     cin>>c;
     switch(c)
     {
       case 1: cout<<"\nEnter row and column(square matrix only)";
	       cin>>r>>c;
	       cout<<"\nEnter the elements";
	       for(i=0;i<r;i++)
		 {for(j=0;j<c;j++)
		   cin>>a[i][j];
		 }
	       break;
       case 2: cout<<"\nMatrix is";
	       for(i=0;i<r;i++)
	       {
		 cout<<"\n";
		 for(j=0;j<r;j++)
		 cout<<a[i][j]<<" ";
	       }
	       break;
       case 3: cout<<"\nUpper triangle matrix\n";
	       u_triangle(a,r);
	       break;
       case 4: cout<<"\nLower triangle matrix\n";
	       l_triangle(a,r);
	       break;
       case 5: cout<<"\nExit";
	       exit(0);
      default: cout<<"\nWrong choice";
     }
   cout<<"\nDo you want to continue";
   cin>>ch;
   }while( ch=='Y'|| ch=='y');
   getch();
}