HP 3000 Manuals HP 3000 Manuals
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.
Click here to view figure.
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).
Table 3-1. Categories of Input/Output Routines
-------------------------------------------------------------------------------------------------
| | | | |
| | Sequential I/O | Textfile I/O | Direct I/O |
| | | | |
-------------------------------------------------------------------------------------------------
| | | | |
| Opening Procedures | | | |
| | reset | reset | open |
| | rewrite | rewrite | |
| | append | append | |
| | | | |
-------------------------------------------------------------------------------------------------
| | | | |
| Input Procedures | | | |
| | get | get | get |
| | read | read | read |
| | | readln | readdir |
| | | | |
-------------------------------------------------------------------------------------------------
| | | | |
| Output Procedures | | | |
| | put | put | put |
| | write | write | write |
| | | writeln | writedir |
| | | page | |
| | | prompt | |
| | | overprint | |
| | | | |
-------------------------------------------------------------------------------------------------
| | | | |
| Positioning Procedure | None | None | seek |
| | | | |
-------------------------------------------------------------------------------------------------
| | | | |
| Association | | | |
| Procedures | associate | associate | associate |
| | disassociate | disassociate | disassociate |
| | | | |
-------------------------------------------------------------------------------------------------
| | | | |
| Status Functions | | | |
| | eof | eof | eof |
| | | eoln | lastpos |
| | | linepos | maxpos |
| | position | | position |
| | | | |
-------------------------------------------------------------------------------------------------
| | | | |
| Closing Procedure | close | close | close |
| | | | |
-------------------------------------------------------------------------------------------------