SOME COMPUTER STUFF ON C,JAVA,TALLY,BCA,SOLVED PAPERS

import java.io.*; import java.lang.*; import javax.swing.*; import javax.swing.event.*; import java.awt.*; import java.awt.event.*; import calculate.calc; public class cal implements ActionListener { JFrame jf; JToolBar jtb; JButton jbadd,jbsub,jbmul,jbdiv,jbclear,jbequal; JTextField jtf; calc ca2=new calc(); int val; int flag=0; cal() { frame(); toolbar(); textfield(); button(); jf.setVisible(true); } void frame() { jf=new JFrame("calculator"); jf.setSize(500,500); jf.setDefaultCloseOperation(jf.EXIT_ON_CLOSE); } void toolbar() { jtb=new JToolBar(); jf.add(jtb,BorderLayout.NORTH); } void textfield() { jtf=new JTextField(); jtb.add(jtf);         jtf.addMouseListener(new MouseAdapter(){                  public void mouseClicked(MouseEvent e){                 jtf.setText("");             }    ...