Finding the smallest in e.g. 20 numbers is easy for humans - we just scan them. But what about finding the smallest value from 50,000 numbers, presented to you on a stack of paper?

How might you solve this problem? Think!

One way is to use another piece of paper. Look through the numbers in turn, and write the smallest so far on the paper.

We keep on looking - if we find a smaller one than the one we previously noted, we cross the old value out, and write down the new one.

The piece of paper acts like a variable. It only holds one value at once, and this value changes as we work through the list. Let us now look at coding the plan in VB.

Problem

Some points about the problem:

• we need a loop, which keeps running as long as -999 is not entered.
• we need a variable to keep track of the current smallest as we work through the numbers. A meaningful name helps - e.g. smallestSoFar
• we need an IF to compare the smallest so far with the number we have just input. Sometimes, we need to alter the smallest so far.
• When a human does the job with a piece of paper, what is initially written on the paper? 0? - but what if an overdraft has a value of 0?

A solution

n=inputBox...                    ' get first number
while...
    ...
    n=inputBox...                ' get next number
end while

dim number as double

number=CDbl(inputBox("Enter balance"))
while number <> -999
    TextBox1.appendText( CStr( number))
    number=CDbl(inputBox("Enter balance"))
end while

• if it is smaller, then we set the smallest so far to the number
• if it is NOT smaller, then we leave the smallest so far unaltered - i.e. we do nothing.

dim number as double
dim smallestSoFar as double

smallestSoFar = 100000    ' has to be bigger than any of the input numbers
number=CDbl(inputBox("Enter balance"))
while number <> -999
    if number < smallestSoFar then
        smallestSoFar = number
    end if
    number=CDbl(inputBox("Enter balance"))
End While
MessageBox.Show("Smallest is:  " & smallestSoFar)

• an alternative - slightly better - way is to set smallestSoFar to the first number in the list. Then, the code still works even if all the overdrafts are above 100000
• we should test the code. merely testing it with e.g 100 90 -999 and verifying that it picks 90 as the smallest is not enough. (What if it always picked the last number?)

  We might try:

  10 20 7 -999
  7 10 20 -999
  10 7 20 30 -999
  7 -999
  
  

Alternatively...

Later, you will see how to use the VB listbox control, which can automatically sort numbers into ascending order.