HP Pascal/iX Programmer's Guide (31502-90023)

3- 4
Textfiles
A textfile is a logical file that is subdivided into lines, each of which
ends with an end-of-line marker. The components of a textfile are of
type char , but a textfile declaration specifies the type text , not FILE
OF char .
The standard files input and output are textfiles. If you declare them
in the program header, they are the default file parameters for all of
the sequential input and output procedures, respectively.
Example
PROGRAM prog (input,output);
VAR
tfile : text;
c : char;
BEGIN
.
.
.
read(tfile, c); {Reads from tfile}
read(c); {Reads from input}
write(c); {Writes to output}
END.
The preceding program has three textfiles: the standard textfiles input
and output, and the file tfile.
End-of-line markers are not file components, and are not of type char.
The predefined procedure writeln writes them to the file (see "Textfile
Input/Output" ). An end-of-line marker always precedes the
end-of-file mark in a textfile, whether writeln wrote the last component
to the file or not.
Current Position Indexes
Every logical file has a current position index that indicates either its
current component, an end-of-file marker, or (in a textfile) an
end-of-line marker. This index is an integer--the ordinal number of the
current component or marker. A file's current component is the component
that the next I/O operation on that file will input or output.
Figure 3-3 illustrates the relationship between current position
index and current component.
Figure 3-3. Relationship Between Current
Position Index and Current Component