programming-for-dummies

Using a Stack 363
Like a collection or a dictionary, a stack can typically hold different data,
such as both numbers and strings.
The only way you can store or remove data from a stack is through the top
of the stack. To add data to a stack, you push that data on the stack. In Visual
Basic.NET, you specify the Push command along with the stack name like
this:
Dim BlowMyStack as New Stack
BlowMyStack.Push (“My cat”)
This command stores the string “My cat” on top of the stack. Each time you
add another chunk of data to a stack, you have to put that data on the top,
which pushes any existing data farther down the stack.
If you added the string “My cat,” the number 108.75, and the string “Fat dog,”
the stack would look like Figure 4-2.
Dim BlowMyStack as New Stack
BlowMyStack.Push (“My cat”)
BlowMyStack.Push (108.75)
BlowMyStack.Push (“Fat dog”)
Figure 4-2:
When you
add data
to a stack,
the oldest
data keeps
getting
pushed
farther down
the stack.
108.75 Fat dog
My cat 108.75
My cat
Fat dog
108.75
My cat
Book III
Chapter 4
Stacks, Queues,
and Deques
Removing data from a stack
After you store data in a stack, the only way you can remove data from that
stack is by removing the top item. Removing data from a stack is known as
popping the data off the stack. If you just want to retrieve the data from a
stack without removing it, you can use a Peek command, which lets you
retrieve the top item from a stack.