Sorting a List of Integers

An algorithm for sorting a list of numbers on paper could be:

Scan through the list looking for the smallest number
Put that number on a second list
Cross the number off of the first list
Repeat the first 3 steps until there are no more numbers left

This requires two lists and "crossing off" numbers is not easy to represent. A better way is to sort the items in place. We put the smallest item in its proper place by swapping it with the item that is already there. The pseudo-code for this could be:

  For count going from 0 through length - 2
    Find minimum value in list[count . . length - 1]
    Swap minimum value with list[count]

Notice that the loop only goes up to length - 2; when count equals length - 1, the last value list[count] will be in the correct position.

Suppose you have two integer variables, x and y. To swap (exchange) their contents, why can't you simply do the following?

x = y;
y = x;

Swapping the contents of two variables requires a temporary variable. You would need to do the swap this way:

int temp;

temp = x;
x = y;
y = temp;

A graphical view of this sort method is here.

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