TOPS-20 PASCAL Language Manual - Bitsavers

PASCAL DATA TYPES
Example 3
F I 1...[
TY'ial
Datf:'~
OF RECOf~D
INTEGER;
RECOF~D
Month: (Jan, Feb, Mar, Apr, Mas, Jun,
Jul, Aug, Sep, Oct, Nov, Dec);
D a ~:1 : 1.. 3 l ~
Y€·~ar : INTEGER
END;
Temp, Pressure : INTEGER;
Yield, Purits : REAl...
END;
The VAR Declaration specifies a file of records. To access the fields
of the record components, you specify ResultsA.Trial,
ResultsA.Date.Month, and so on.
2.3.4.1 Internal and External Files - A file that is local to a
program or subprogram is called an internal file. You can use an
internal file only within the scope of the program or subprogram in
which it is declared. The system retains an internal file only during
execution of the declaring program or subprogram. After execution the
file is no longer accessible. The system creates a new file variable
with the same name the next time it executes the declaring unit. The
contents of the old file are not available. Internal files are not
specified in the program heading. Only internal files can be
components of structured types.
An external file exists outside the scope of the program in which it
is declared. An external file can be created by the current PASCAL
program, another PASCAL program, or a program written in another
language. The system retains the contents of external file variables
after the execution of the program. You must specify the names of
external file variables in the program heading. External files cannot
be part of a structured type.
2.3.4.2 Text Files - A text file is a file with components of type
CHAR. PASCAL defines a file type called TEXT. To declare a text
file, specify a variable of type TEXT, for example:
VAR Poem
TEXT;
The text file variable POEM is a file of characters. Text files are
divided into lines. Each line ends with a line-separator character.
You cannot use this character directly, but you can refer to it
indirectly through the predeclared procedures READLN and WRITELN and
the predeclared function EOLN.
The pred~clared file variables INPUT and OUTPUT are files of type
TEXT. These files are the defaults for all the predeclared text file
procedures described in Chapter 7. Note that TEXT is not equivalent
to FILE OF CHAR.
Example
VAR Guide, Manual:
TEXT;
This example declares the Variables Guide and Manual as text files.
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