Computer Programming Concepts and Visual Basic David I. Schneider

SUMMARY
1. A fixed-length string is a variable declared with a statement of the form Dim
var As String * n. The value of var is always a string of n characters.
2. A record is a composite user-defined data type with a fixed number of fields
each of which can be of most data types. Type statements [in this text appearing
in the (Declarations) section of a BAS Module] define record types and
Dim statements are used to declare a variable to be of that type.
3. After a record type has been specified, the associated random-access file is an
ordered collection of record values numbered 1, 2, 3, and so on. Record values
are placed into the file with Put statements and read from the file with Get
statements. At any time, the value of LOF(n) / Len(recordVar) is the number of
the highest record value in the file and the value of Loc is the number of the
record value most recently accessed by a Put or Get statement.
PROGRAMMING PROJECTS
1. Balance a Checkbook. Write an interactive program to request information
(payee, check number, amount, and whether or not the check has cleared) for
each check written during a month and store this information in a random file.
The program should then request the balance at the beginning of the month and
display the current balance and the payee and amount for every check still outstanding.
2. A teacher maintains a random-access file containing the following information
for each student: name, social security number, grades on each of two hourly
exams, and the final exam grade. Assume the random-access file
GRADES.TXT has been created with string fields of lengths 25 and 11 and
three numeric fields, and all the names and social security numbers have been
entered. The numeric fields have been initialized with zeros. Write a program
with the five command buttons “Display First Student,” “Record Grade(s) &
Display Next Student,” “Locate Student,” “Print Grade List,” and “Done” to
allow the teacher to do the following.
(a) Enter all the grades for a specific exam.
(b) Locate and display the record for a specific student so that one or more
grades may be changed.
(c) Print a list of final grades that can be posted. The list should show the last
four digits of the social security number, the grade on the final exam, and
the semester average of each student. The semester average is determined
by the formula (exam1 + exam2 + 2 * finalExam) / 4.
Summary 255