
Bubble Sort Logic
To understand bubble sort, think of an air bubble rising in water
To sort N items, N passes are made through the data.
 The result of the first pass is that the smallest item is in the
last location of the array.
 The result of the second pass is that the second smallest item is
in the second last location of the array.
 etc.
 After N passes, the entire array is sorted.
The operation in each pass is as follows:
 First, the values in the first two locations are compared. If necessary
the values are exchanged, so that the smaller one is last.
 Then, the values in the second and third locations are compared.
If necessary the values are exchanged, so that again the smaller one
is last.
 This process repeats to the end of the array.
 In effect, the smaller item bubbles its way towards the top. It keeps
on going until either it reaches the top (and the pass ends), or it
strikes a smaller item. In that case it stops itself, and gives that
smaller item a nudge to start it on its way.
If a complete pass is made without any exchanges being made, the data
must already be sorted. This is easily checked. Thus it might be possible
to halt the algorithm without going through all N passes.
Algorithm
last := length;
sorted := false;
while not (sorted) loop
sorted := true;  assume list sorted
for check in (1 .. last1) loop
if list (check) < list (check+1)
swap list(check)
and list(check+1)
sorted :=
false
end if
end loop
last := last  1;
end loop
Graphical look to the Bubble sort
Basic Code
MyArray(50)
Number
Count
'*** Make an array of random numbers ***
CLS
PRINT
PRINT "Initial random array :"
PRINT
RANDOMIZE TIMER
FOR Count = 1 TO UBOUND(MyArray)
Number = (RND * 5000) + 1
MyArray(Count) = Number
PRINT MyArray(Count);
NEXT Count
Number = UBOUND(MyArray)
'*** Do the Bubblesort ***
FOR Count = 1 TO Number
FOR Counter = 1 TO Number
IF MyArray(Counter) > MyArray(Count) THEN SWAP MyArray(Count), MyArray(Counter)
NEXT Counter
NEXT Count
'*** Print the sorted array ***
PRINT
PRINT
PRINT "Bubble sorted array :"
PRINT
FOR Count = 1 TO Number
PRINT MyArray(Count);
NEXT Count
END
