// exj6.java   example file  create function or procedure and call

import java.io.*;  // needed for input and output

public class exj6  // class name same as file name
{
  // declarations for entire class may go here
    
  public exj6() // constructor same as class name
  {
    // declarations for this procedure go here
    // typically first, yet may be in code, just before use

    int i, j;
    int jj[] = new int[1]; // single value  made into an array to get return
    double arr[][]={{1.0,2.0,3.0},{4.0,5.0,6.0}};
    double val;

    System.out.println("exj6.java running");

   // call proc1, all functions and procedures after constructor
    proc1(7);
    // use funct1
    i = funct1(2, 3);
    System.out.println("funct1(2,3) returns "+i);
    val = sum(arr); // size of array found in sum
    System.out.println("sum(arr)= "+val);
    i = ret2(i, jj);  // pass jj by address so it can be changed
    System.out.println("ret2 i="+i+", jj="+jj[0]);
    System.out.println("end exj6.java");
    
  } // end constructor exj6

  double sum(double A[][]) // determine size inside
  {
    double asum = 0.0;
    int n = A.length; 
    int m = A[0].length;
    for(int i=0; i<n; i++)   // for exactly one statement, no {} OK
      for(int j=0; j<m; j++)
        asum += A[i][j];
    A[n-1][m-1] = 0.0;       // can change valuse in an array
    return asum;
  } // end asum   optional comment

  int ret2(int i, int j[]) // jj is reaaly just one value
  {
    j[0] = i+2;   // second formal parameter changed
    return i+1;
  } // end ret2   optional comment 

  void proc1(int i)  // void  means no return value, this i is local
  {                  // could be at end of previous line
    System.out.println("proc1 called with i= "+i);
  } // end proc1    optional comment

  int funct1(int i, int j) // int is return type
  {
    int sum;      // optional return variable
    sum = i + j;
    return sum;   // could have been  return i+j;
  }

  public static void main (String[] args) //  typically last
  {
    new exj6(); // run the constructor
  }
} // end class exj6