Teach Yourself Borland C++ in 14 Days - portal

6
202 Day 6
components at one time. For example, to change the width of several
components at one time, you can select all the buttons and then modify
the Width property in the Object Inspector. When you press Enter or
move to another property, all the components you selected will have
their Width property modified.
Figure 6.14 shows the Object Inspector when a Memo component is selected.
Figure 6.14.
The Object Inspector
showing Memo
component properties.
NOTE
On Day 5, “C++ Class Frameworks and the Visual Component Model,” I talked about
properties. I discussed how properties can be integer values, enumerations, sets, other objects,
strings, and other types. The Object Inspector deals with each type of property according to
the data type of the property. C++Builder has several built-in property editors to handle data
input for the property. For example, the Top property accepts an integer value. Because an
int is a basic data type, no special handling is required, so the property editor is fairly basic.
The property editor for this type of property allows you to type a value (such as Top, Left,
Width, and Height) directly in the Value column for integer properties.
In most cases, the property editor does parameter checking for any
properties in which you can enter an integer value. The Width property,
for instance, cannot be a negative number. If you attempt to enter a
negative number for the width of a control, C++Builder will force the
width to the minimum allowed for that control (usually 0). If you enter
a string value for a property that expects an integer value, C++Builder
will display an error message. It is the job of the property editor to do
parameter checking.