Computer Programming Concepts and Visual Basic David I. Schneider

7.1 SEQUENTIAL FILES
Throughout this text we have processed data from files created with Windows’ Notepad and
saved on a disk. Such files are stored on disk as a sequence of characters. (Two special characters,
called the “carriage return” and “line feed” characters, are inserted at the end of each
line to indicate where new lines should be started.) Such files are called sequential files or text
files. In this section, we create sequential files from Visual Basic programs and develop techniques
for using sequential files.
■ CREATING A SEQUENTIAL FILE
There are many ways to organize data in a sequential file. The technique presented here is
easy to implement. The following steps create a new sequential file and write data to it.
1. Choose a file name. A file name can contain up to 255 characters consisting of
letters, digits, and a few other assorted characters (including spaces and periods).
In this book we use 8.3 format names; that is, each name has a base name
of at most 8 characters, and optionally a period followed by a three-letter extension.
(Such names are recognized by all utility programs.)
2. Choose a number from 1 through 511 to be the reference number of the file.
While the file is in use, it will be identified by this number.
3. Execute the statement
Open “filespec” For Output As #n
where n is the reference number. This process is referred to as opening a file
for output. It establishes a communications link between the computer and the
disk drive for storing data onto the disk. It allows data to be output from the
computer and recorded in the specified file.
4. Place data into the file with the Write # statement. If a is a string, then the statement
Write #n, a
writes the string a surrounded by quotation marks into the file. If c is a number,
then the statement
Write #n, c
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