View source for CIS 3020 Part 9

==Command Line Arguments==
* When you execute a Java program, you can provide values directly to the program
* These values are called "command line arguments" since they are in the command to execute your program:
 java Print2CLArgs 123 hello
<pre>
class Print2CLArgs {
  public static void main (String[] arg) {
    ...
    System.out.println(arg[0]);
    System.out.println(arg[1]);
    ...
  }
}
</pre>
* Remember: the command line arguments are strings
* Suppose we execute: <code>java PrintSum 3 5</code>
* And PrintSum contains:
 System.out.println(arg[0] + arg[1]);
* What will be output?
 35
* What you need to write is:
<pre>
int i1 = Integer.parseInt(arg[0]);
int i2 = Integer.parseInt(arg[1]);
System.out.println(i1 + i2);
</pre>
==Quicksort==
===Algorithm===
# If ''first < last'' then begin
# Partition the elements in the subarray ''first..last'' so that the pivot value is in place (in position ''pivIndex'')
# Apply ''quickSort'' to the first subarray ''first..pivIndex-1''
# Apply ''quickSort'' to the second subarray ''pivIndex-1..last''

The two stopping cases are:
# (first = last) -- Only one value in subarray so sorted
# (first > last) -- no values in subarray so sorted
===How do we partition?===
# Define the pivot value as the contents of ''val[first]''
# Initialize ''up'' to ''first'' and ''down'' to ''last''
# Repeat 4-6 until ''up'' meets or passes ''down''
# Increment ''up'' until ''up'' selects the first element greater than the pivot value
# Decrement ''down'' until it selects the first element less than the pivot value
# If ''up < down'' exchange their values
# Exchange ''val[first]'' and ''val[down]''
# Define ''pivIndex'' as ''down''