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The commands to compile and execute shrvar_prog.p and shrvar_mod.p

hostname% pc shrvar_prog.p shrvar_mod.p shrvar_prog.p:

shrvar_mod.p: Linking: hostname% a.out

From MAIN, before PROC: 1

From PROC: 1

From MAIN, after PROC : 2

Using extern Option to Share Routines

If a program or module calls a procedure not defined in that unit, you must declare it with either the extern or external routine option. For instance, in the previous example, the procedure proc is defined in shrvar_mod.p, but used in shrvar_prog.p. Thus, it is declared as external in shrvar_prog.p. Also, proc must also be defined as public in shrvar_mod.p, which is the default.

Using include Files to Share Variables and Routines

The include file contains the declarations for the program. Placing all program declarations in a single file makes your program more consistent and easier to maintain.

To use this feature, place the number sign character (#) in the first position of a line immediately followed by the word include, and then a file name enclosed in angle brackets (< and >) or double quotation marks ("). The different enclosures (<> and "") affect the search order for files. The syntax for the #include directive is determined by cpp(1).

When the compiler encounters the #include in the input, it inserts the lines from the included file into the input stream.

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Pascal 4.0 User’s Guide