Computer Programming Concepts and Visual Basic David I. Schneider

434 Computer Programming Concepts and Visual Basic
FOR/NEXT The statement For index = a To b Step s sets the value of the variable index to
a and repeatedly executes the statements between itself and the statement Next index. Each
time the Next statement is reached, s is added to the value of index. This process continues
until the value of index passes b. Although the numbers a, b, and s may have any numeric
type, the lower the precision of the type, the faster the loop executes. The statement For index
= a To b is equivalent to the statement For index = a To b Step 1. The index following the
word Next is optional.
FORECOLOR The property ForeColor determines the color used to display text, captions,
graphics, and Printed characters. If the ForeColor property of a form or picture box is
changed, subsequent characters will appear in the new color. For a text box, command button,
or label, text or caption is immediately changed to the new color. [color]
FORMAT The value of the function Format(expression, str) is a string representing expression
(a number, date, time, or string) formatted according to the rules given by str. Format is
useful when assigning values to the Text property and when Printing to a form, picture box,
or the printer.
Numeric output can be formatted with commas, leading and trailing zeros, preceding or
trailing signs (+ or –), and exponential notation. This is accomplished either by using for str
the name of one of several predefined numeric formats or by combining in str one or more
of the following special numeric formatting characters: #, 0, decimal point (period), comma,
%, E–, and E+. The expression to be formatted can evaluate to one of the numeric types or a
string representing a number.
Predefined numeric formats include “General Number,”which displays a number as is;
“Currency,”which displays a number with a leading dollar sign and with commas every three
digits to the left of the decimal, displays two decimal places, and encloses negative numbers
in parentheses; “Fixed,” which displays two digits to the right and at least one digit to the left
of the decimal point; “Standard,”which displays a number with commas and two decimal
places but does not use parentheses for negative numbers; “Percent,” which multiplies the
value by 100 and displays a percent sign after two decimal places; and “Scientific,”which
displays numbers in standard scientific notation. For example, Format(–5432.352, “Currency”)
gives the string “($5,432.35)”.
The symbol # designates a place for a digit. If the number being formatted does not need
all the places provided by the #’s given in str, the extra #’s are ignored. The symbol 0, like #,
designates a place for a digit. However, if the number being formatted does not need all the
places provided by the 0’s given in str, the character 0 is displayed in the extra places. If the
number being converted has more whole part digits than there is space reserved by #’s and
0’s, additional space is used as if the format string had more #’s at its beginning. For example,
Format(56, “####”) yields “56”, Format(56, “#”) yields “56”, Format(0, “#”) yields “”,
Format(56, “0000”) yields “0056”, Format(56, “0”) yields “56”, and Format(0, “0”) yields
“0”.
The decimal point symbol (.) marks the location of the decimal place. It separates the
format rules into two sections, one applying to the whole part of the number and the other to
the decimal part. When included in the format string, a decimal point will always appear in
the resulting string. For example, Format(56.246, “#.##”) yields “56.25”, Format(.246,
“#.##”) yields “.25”, Format(.246, “0.##”) yields “0.25”, and Format(56.2, “0.00”) yields
“52.20”.
The comma symbol (,) placed to the left of the decimal point between #’s and/or 0’s causes
commas to be displayed to the left of every third digit to the left of the decimal point, as
appropriate. If commas are placed to the immediate left of the decimal point (or to the right
of all #’s and 0’s when the decimal-point symbol is not used), then before the number is formatted,
it is divided by 1000 for each comma, but commas will not appear in the result. In
order to divide by201000’s and display commas in the result, use format strings like
“#,#,.00”, which displays the number with commas in units of thousands, and “#,#,,.00”,
which displays the number with commas in units of millions. For example, Format(1234000,
“#,#”) yields “1,234,000”, Format(1234000, “#,”) yields “1234”, Format(1234000, “#,.”)