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7/27/2019 6week Chapter6 Function.ppt
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Chapter 6 Functions
Week: 6
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Objectives
In this lesson you will learn: MsgBox Function
InputBox Function
Math Functions
Common String-Manipulation Functions
Time Functions
RGB Function QBColorFunction
LoadPicture Function
Format Function
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MsgBox FunctionDisplays a message in a dialog box, waits for the
user to click a button, and returns an Integer indicating
which button the user clicked.Syntax
MsgBox(prompt[, buttons] [, title])
PromptRequired. String expression displayed as the
message in the dialog box.
If prompt consists of more than one line, you canseparate the lines using a carriage return character
(Chr(13)), a linefeed character (Chr(10)), or carriage
return linefeed character combination (Chr(13) &
Chr(10)) between each line.
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But tonsOptional.
Numeric expression that is the sum of values
specifying the number and type of buttons to
display, the icon style to use, the identity of thedefault button, and the modality of the message
box.
If omitted, the default value for buttons is 0.
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The but tonsargument settings are:
Constant Value DescriptionvbOKOnly 0 OK
vbOKCancel 1 OK Cancel
vbAbortRetryIgnore 2 Abort Retry Ignore
vbYesNoCancel 3 Yes No Cancel
vbYesNo 4 Yes NovbRetryCancel 5 Retry Cancel
vbCritical 16 X Critical Message icon
vbQuestion 32 ? Warning Query iconvbExclamation 48 ! Warning Message icon
vbInformation 64 i Information Message
icon
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t i t le
Optional.String expression displayed in
the title bar of the dialog box.If you omit title, the application
name is placed in the title bar.
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Return Values
Constant Value Description
vbOK 1 OK
vbCancel 2 Cancel
vbAbort 3 Abort
vbRetry 4 Retry
vbIgnore 5 Ignore
vbYes 6 Yes
vbNo 7 No
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InputBox FunctionDisplays a prompt in a dialog box, waits for
the user to input text or click a button, andreturns a String containing the contents of
the text box.
SyntaxInputBox (prompt[, title] [, default] )
Prompt
Required. String expression displayed as the
message in the dialog box.
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t i t le
Optional.String expression displayed in
the title bar of the dialog box.If you omit title, the application
name is placed in the title bar.
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Default
Optional.
String expression displayed in the
text box as the default response if no
other input is provided.
If you omit default, the text box is
displayed empty.
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Math Functions
Abs Function
Returns a value of the same type that ispassed to it specifying the absolute value of
a number.
Syntax
Abs(number)
To compute the absolute value of a number.The required number argument can be any
valid numeric expression. If number is an
un-initialized variable, zero is returned.
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Sgn Function
Returns a Variant (Integer) indicating the sign of a
number.
Syntax:
Sgn(number)
The required number argument can be any validnumeric expression.
Return Values
If number is Sgn returns
Greater than zero 1
Equal to zero 0
Less than zero -1
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Sin Function
Returns a Double specifying the sine of an angle.
Syntax
Sin(number)
The required number argument is a Double or any
valid numeric expression that expresses an angle
in radians.
To convert degrees to radians, multiply degrees by
pi/180. (pi=3.1415926)
To convert radians to degrees, multiply radians by
180/pi.
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Cos Function
Returns a Double specifying the cosine of
an angle.
Syntax
Cos(number)
The required number argument is a Double
or any valid numeric expression that
expresses an angle in radians.
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Atn Function
Returns a Double specifying the arctangentof a number.
Syntax
Atn(number)
The required number argument is a Doubleor any valid numeric expression.
The Atn function takes the ratio of two sidesof a right triangle (number) and returns the
corresponding angle in radians.The ratio is the length of the side oppositethe angle divided by the length of the sideadjacent to the angle.
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Sqr Function
Returns a Double specifying thesquare root of a number.
SyntaxSqr(number)
The required number argument is aDouble or any valid numeric
expression greater than or equal to
zero.
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Example:
MySqr = Sqr(4) ' Returns 2.MySqr = Sqr(23)
' Returns 4.79583152331272.MySqr = Sqr(0) ' Returns 0.MySqr = Sqr(-4)
' Generates a error.
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Int, Fix Functions
Returns the integer portion of a number.
Syntax
Int(number)
Fix(number)
The required number argument is a Double or
any valid numeric expression.
MyNumber = Int(99.8) ' Returns 99MyNumber = Fix(99.2) ' Returns 99
MyNumber = Int(-99.8) ' Returns -100
MyNumber = Fix(-99.8) ' Returns -99
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Exp Function
Returns a Double specifying e (the baseof natural logarithms) raised to a power.
Syntax
Exp(number)
The required number argument is a
Double or any valid numeric expression.
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Log Function
Returns a Double specifying the natural
logarithm of a number.
Syntax
Log(number)
The required number argument is a
Double or any valid numeric expression
greater than zero.
Ln(x) Log(x)
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The natural logarithm is the logarithm to the base e.
The constant e is approximately 2.718282.
You can calculate base-n logarithms for anynumber x by dividing the natural logarithm of x by
the natural logarithm of n as follows:
Logn(x) = Log(x) / Log(n)
Lg(x) Log(x)/Log(10)
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Rnd Function
Returns a Single containing a random
number.
Syntax
Rnd[(number)]
The optional number argument is a Single
or any valid numeric expression.
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Return Values
If number is Rnd generates
Less than zero The same number every time,
using number as the seed.
Greater than zero The next random number inthe sequence.
Equal to zero The most recently generated
number.
Not supplied The next random number in
the sequence
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The Rnd function returns a value less
than 1 but greater than or equal to zero.0
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To produce random integers in a
given range, use this formula:
Int((upperbound - lowerbound + 1) * Rnd +
lowerbound)
Here, upperbound is the highestnumber in the range, and
lowerbound is the lowest number in
the range.Generate random value between
1 and 6.
MyValue = Int((6 * Rnd) + 1)
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Common String-Manipulation Functions
Left(string, length)
Righ t(str ing , leng th)
Mid(s tr ing , start [ , leng th ])
Left(abcdef, 3) abc
Right(abcdef, 3) defMid(abcdef, 3,2) cd
Mid(abcdef, 3) cdef
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Instr Function
Returns a Variant (Long) specifying the
position of the first occurrence of one string
within another.
SyntaxInStr([start, ]string1, string2)
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start
Optional. Numeric expression that sets the
starting position for each search. If omitted, searchbegins at the first character position.
string1
Required. String expression being searched.
string2
Required. String expression sought.
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Return Values
If InStr returns
string1 is zero-length 0
string2 is zero-length startstring2 is not found 0
string2 is found within string1 Position
at which match is found
start > string2 0
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LTrim, RTrim, and Trim Functions
Returns a Variant (String) containing a copy of a
specified string without leading spaces (LTrim),trailing spaces (RTrim), or both leading and
trailing spaces (Trim).
Syntax
LTrim(string)
RTrim(string)
Trim(string)
The required string argument is any valid string
expression.
If string contains Null, Null is returned.
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Len Function
The Len function tells you how many characters
a String contains.
Syntax
Len(string)
The Len function syntax has this argument:
string
Any valid string expression. If string containsNull, Null is returned.
Asc Function
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Asc Function
Returns an Integer representing the character
code corresponding to the first letter in a string.
Syntax
Asc(string)
The required string argument is any valid stringexpression.
If the string contains no characters, a run-time
error occurs.MyNumber = Asc("A") ' Returns 65
MyNumber = Asc("a") ' Returns 97
M Number = Asc "A le" ' Returns 65
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Chr Function
Returns a String containing the character associated with
the specified character code.
Syntax
Chr(charcode)
The required charcode argument is a Long that identifies acharacter.
Remarks
Numbers from 0-31 are the same as standard, nonprintableASCII codes.
For example, Chr(10) returns a linefeed character.
The normal range for charcode is 0-255.
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MyChar = Chr(65) ' Returns AMyChar = Chr(97) ' Returns aMyChar = Chr(48) ' Returns 0
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LCase Function
Returns a String that has been converted to
lowercase.
Syntax
LCase(string)
The required string argument is any valid string
expression. If string contains Null, Null is returned.
RemarksOnly uppercase letters are converted to
lowercase; all lowercase letters and nonletter
characters remain unchanged.
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UCase Function
Returns a Variant (String) containing the specifiedstring, converted to uppercase.
Syntax
UCase(string)
The required string argument is any valid string
expression.
Remarks
Only lowercase letters are converted to
uppercase; all uppercase letters and nonletter
characters remain unchanged.
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x$ = "Hello World 1234"Y$ = Lcase(x$)' Returns "hello world 1234"
Z$ = UCase(x$)
' Returns "HELLO WORLD 1234"
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Val Function
Returns the numbers contained in astring as a numeric value of appropriate
type.
Syntax
Val(string)
The required string argument is any validstring expression.
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The Val function stops reading the
string at the first character it can'trecognize as part of a number.
MyValue = Val("2457") ' Returns 2457
MyValue = Val(" 2 45 7") ' Returns 2457
MyValue = Val("24 and 57") ' Returns 24
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Str Function
Returns a Variant (String) representation
of a number.
Syntax
Str(number)
The required number argument is a Long
containing any valid numeric expression.
MyString = Str(459) ' Returns " 459"
MyString = Str(-459.65) ' Returns "-459.65"
MyString = Str(459.001) ' Returns " 459.001"
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String Function
Returns a Variant (String) containing a repeating character
string of the length specified.
Syntax
String(number, character)
The String function syntax has these named arguments:
number
Required; Long. Length of the returned string.
character
Required; Variant. Character code specifying the character
or string expression whose first character is used to build
the return string.
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MyString = String(5, "*")
' Returns "*****"MyString = String(5, 42)
' Returns "*****"
MyString = String(10, "ABC")' Returns AAAAAAAAAA"
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StrReverse Function
Returns a string in which the character order
of a specified string is reversed.
Syntax
StrReverse(expression)The expression argument is the string whose
characters are to be reversed.
If expression is a zero-length string (""), azero-length string is returned.
StrReverse(abcdefGH) HGfedcba
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Time Functions
Now Function
Returns a Variant (Date) specifying the currentdate and time according your computer's system
date and time.
Syntax
Now
Example:
Dim Today
Today = Now ' Assign current system date and
time.
Time Function
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Time Function
Returns a Variant (Date) indicating the current
system time.
Syntax
Time
Time Function Example
This example uses the Time function to return
the current system time.
Dim MyTime
MyTime = Time
' Return current system time.
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RGB Function
Returns a Long whole number
representing an RGB color value.
Syntax
RGB(red, green, blue)
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red
Required; Variant (Integer). Number in the
range 0-255, inclusive, that represents thered component of the color.
Green
Required; Variant (Integer). Number in the
range 0-255, inclusive, that represents the
green component of the color.
Blue
Required; Variant (Integer). Number in therange 0-255, inclusive, that represents the
blue component of the color.
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LoadPicture Function
Loads a graphic into a forms Picture property, a
PictureBox control, or an Image control.Syntax
LoadPicture([filename])
Filename
Optional. String expression specifying a filename.
Can include folder and drive.
If no filename is specified LoadPicture clears the
Image or PictureBox control.
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Format Function
Returns a Variant (String)containing an expression formatted
according to instructions contained
in a format expression.
Syntax
Format(expression[, format])
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Expression
Required. Any valid expression.
Format
Optional. A valid named or user-defined format expression.
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MyTime = #17:04:23#
MyDate = #January 27, 1993#
MyStr = Format(MyTime, "h:m:s")
' Returns "17:4:23".
MyStr = Format(MyTime, "hh:mm:ss AMPM")
' Returns "05:04:23 PM".
MyStr = Format(MyDate, "dddd, mmm d yyyy")' Returns "Wednesday, Jan 27 1993".
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' If format is not supplied, a string is returned.
MyStr = Format(23) ' Returns "23".
' User-defined formats.
MyStr = Format(5459.4, "##,##0.00")
' Returns "5,459.40".
MyStr = Format(334.9, "###0.00")' Returns "334.90".
MyStr = Format(5, "0.00%")
' Returns "500.00%".
MyStr = Format("HELLO", "")
' Returns "THIS IS IT".
S
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Summary MsgBox Function InputBox Function
Math Functions Abs , Sgn, Sin ,Cos ,Atn ,Sqr ,Int, Fix,Exp ,Log ,
Rnd
Common String-Manipulation Functions
Left ,Right, Mid , Instr , LTrim, RTrim, Trim ,Len , Asc ,Chr
LCase, UCase, Val, Str, String,StrReverse
Time Functions Now ,Time
Other Functions
RGB ,LoadPicture,Format
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Exercises in the practice lessonPage 148-149:
Exercise:1,2,4,5,6
Homework
Page 147-148:
Question: 1 to 9