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Declaring Variables |
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Usually, a variable is first defined by the dim statement and then used in code; however, at times, a single global variable must be accessible from several compilation units. In such cases, you must use the public modifier when defining this variable, and use the declare statement in each compilation unit from which this variable needs to be accessed.
For example, let us say this is the file foo.tbs:
public dim i as integer ' the integer i is defined in this file, and made into a public variable. It can now be used from other compilation units.
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And this is the file bar.tbs:
i = i + 5 ' this would cause a compiler error. What is i?
' the correct way: declare i as integer ' lets the compiler know that i is defined elsewhere. i = i + 5
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Also, if for some reason you would attempt to use a variable in a single compilation unit before defining it using the dim statement, you will have to use a declare statement before using it to let the compiler know that it exists. For example:
declare i as integer i = 7 ' i has not been defined yet, but we let the compiler know that it is defined elsewhere.
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dim i as integer ' we now define i. Note that here it doesn't have to be public, because it is used in the same compilation unit.
' this example is rather pointless, but just illustrates this single principle.
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