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

3-: 1
Chapter 3 Input/Output
Input/output depends on files: your program reads input from files and
writes output to files. The terms that describe the three varieties of
input/output-- sequential, textfile, and direct --also describe the
associated files.
This chapter:
* Gives general information about files.
* Explains the predefined file-opening procedures and how they
determine whether files are sequential or direct, for input or for
output.
* Defines sequential as it applies to input/output and files, and
explains the predefined routines that support sequential I/O.
* Explains textfile input/output and files, which are subsets of
sequential I/O and files (respectively), and explains the routines
peculiar to them.
* Defines direct as it applies to input/output and files, and
explains the predefined routines that support direct I/O.
* Gives the conditions under which files are closed, and tells what
happens when a file closes.
Figure 3-1 illustrates the relationships between sequential,
textfile, and direct input/output and sequential files, textfiles, and
direct files.
Figure 3-1. Relationships Between I/O Varieties and File Types
Input/output also depends upon the procedures that manipulate files and
the functions that return information about them.
Table 3-1 categorizes the predefined input/output routines two ways:
by purpose (for example, input or output) and by I/O type (sequential,
textfile, or direct).