Computer Programming Concepts and Visual Basic David I. Schneider

58 Computer Programming Concepts and Visual Basic
6. If all the data in a file have been read by Input # statements and another item is
requested by an Input # statement, a box will appear displaying the message
“Input past end of file.”
7. Numeric data in a text box, input box, or file must be a constant. It cannot be a
variable or an expression. For instance, num, 1 / 2, and 2 + 3 are not acceptable.
8. To skip a Print zone, just include two consecutive commas.
9. Print zones are usually employed to align information into columns. Since most
fonts have proportionally-spaced characters, wide characters occupy more than
one fixed-width column and narrow characters occupy less. The best and most
predictable results are obtained when a fixed-pitch font (such as Courier) is
used with print zones.
10. The Tab function cannot be used to move the cursor to the left. If the position
specified in a Tab function is to the left of the current cursor position, the cursor
will move to that position on the next line. For instance, the line
picBox.Print “hello”; Tab(3); “good-bye”
results in the output
hello
good-bye
11. The statement Close, without any reference number, closes all open files.
12. Windows allows you to alternate between Visual Basic and Notepad without
exiting either application. To invoke Notepad with Windows, click on the Start
button; successively select Programs, Accessories, and Notepad; and then click
on Notepad or press the Enter key. Now that both Visual Basic and Notepad
have been invoked, you can go from one application to the other by holding
down the Alt key and repeatedly pressing the Tab key until the name of the other
application appears. When the Alt key is released, the named application
becomes active.
2.6 BUILT-IN FUNCTIONS
Visual Basic has a number of built-in functions that greatly extend its capability. These functions
perform such varied tasks as taking the square root of a number, counting the number of
characters in a string, and capitalizing letters. Functions associate with one or more values,
called the input, a single value, called the output. The function is said to return the output value.
The three functions considered in what follows have numeric input and output.
■ NUMERIC FUNCTIONS: SQR, INT, ROUND
The function Sqr calculates the square root of a number. The function Int finds the greatest integer
less than or equal to a number. Therefore, Int discards the decimal part of positive numbers.
The value of Round (n, r) is the number n rounded to r decimal places. The parameter r
can be omitted. If so, n is rounded to a whole number. Some examples follow:
Sqr(9) is 3. Int(2.7) is 2. Round(2.7) is 3.
Sqr(0) is 0. Int(3) is 3. Round(2.317, 2) is 2.32.
Sqr(2) is 1.414214. Int(-2.7) is -3. Round(2.317, 1) is 2.3.
The terms inside the parentheses can be either numbers (as shown), numeric variables, or numeric
expressions. Expressions are first evaluated to produce the input.