programming-for-dummies

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Elements of a User Interface
Figure 10-7:
Toolboxes
provide
another way
to group
icons for
easy
access.
Giving data to the user interface
Besides giving a program commands, users also need to give a program data
to use for calculating a useful result. At the simplest level, users can just
type in data they want to give the program. To accept typed-in data, user
interfaces need to display a text box.
A text box is nothing more than a box for the user to click and type something
in it. Text boxes are commonly used when the program needs data that
can’t be predicted in advance, such as asking for someone’s name, as shown
in Figure 10-8.
Figure 10-8:
Users can
type any
information
inside a text
box,
including
invalid data.
Text boxes are great for accepting any data, such as names, passwords, or
search phrases, but text boxes also allow users to type in invalid data. To
weed out invalid data, write extra code to verify that any information typed
into a text box is actually valid.