Iteration (Looping) Statements
There are many situations in which you will want to do the same thing again and again, perhaps slightly changing a value each time you repeat the action. This is called iteration or looping. Typically, you’ll iterate (or loop) over a set of items, taking the same action on each. This is the programming equivalent to an assembly line. On an assembly line, you might take a hundred car bodies and put a windshield on each one as it comes by. In an iterative program, you might work your way through a collection of text boxes on a form, retrieving the value from each in turn and using those values to update a database.
VB.NET provides an extensive suite of iteration statements, including
For Each. You can also create a loop by using a statement
Goto. This chapter considers the use of
For. However, you’ll have to wait
until Chapter 3 to learn more about
Creating Loops with Goto
is the most primitive kind of
unconditional branching statement, and it is not much used in modern
programming. Its most common usage was to create looping statements,
and in fact, the
Goto statement is the seed from
which all other looping statements have been germinated.
Unfortunately, it is a semolina seed, producer of spaghetti code and
Programs that use
Goto statements jump around a
Goto can cause your method to loop
back and forth in ways that are difficult to follow.
If you were to try to draw ...