© 2012 emc publishing, llc slide 1 chapter 7 the math class includes shared methods that perform...
TRANSCRIPT
© 2012 EMC Publishing, LLC
Slide 1
Chapter 7
The Math ClassChapter 7
The Math Class
Includes shared methods that perform common math functions.
Math Class methods include:Abs(num) returns the absolute value of num.Sqrt(num) returns the square root of num.Sign(num) returns 1, -1, or 0 when num is
positive, negative, or 0 respectively.
Round(num, places) returns a Double representing
num rounded to ( a specified number ) places
places.
© 2012 EMC Publishing, LLC
Slide 2
Chapter 7
The IsNumeric() FunctionChapter 7
The IsNumeric() Function
Returns True if an argument can be evaluated to a number. False returned otherwise. For example:
text = "123"Me.lblAns.Text = IsNumeric(text)
'Truetext = "1 + 2"Me.lblAns.Text = IsNumeric(text)
'False
Member/Method of Information module
© 2012 EMC Publishing, LLC
Slide 3
Chapter 7
The Format() FunctionChapter 7
The Format() Function
Converts a number to a formatted string.
Member/Method of Strings Class/Module
Include: Currency, Fixed, Percent, Scientific and True/False:
'$4,568.00Me.lblNum.Text = Format(4568, "Currency")'4568.00 Me.lblNum.Text = Format(4568, "Fixed") '45% Me.lblNum.Text = Format(.45, "Percent")'TrueMe.lblNum.Text = Format(1, "True/False")
‘3.14E-09 Me.lblNum.Text = Strings.Format(Math.PI /
1000000000, "Scientific")
© 2012 EMC Publishing, LLC
Slide 4
Chapter 7
Business FunctionsChapter 7
Business Functions
An annuity is a set of payments made on a regular basis for a specified period.
Functions that return information about an annuity:
- Pmt(rate, term, principal) calculates the daily/monthly/yearly payment on a loan->rate and term must match: daily/monthly/yearly
- PV(rate, term, amount) returns the present value of an annuity->rate, term and amount must match
- FV(rate, term, amount) returns the future value of an annuity->rate, term and amount must match
© 2012 EMC Publishing, LLC
Slide 5
Chapter 7
Processing Business DataChapter 7
Processing Business Data
Business applications that prompt the user for currency values and percentage rates should be written to accept a variety of formats. User should be allowed to enter $45000 or 45000. If code not written to accept both formats a run-time error will occur.
The IsNumeric() function returns True when a string of numbers begins with a $. However Val() returns 0 for Val(“$45”) because $ is not recognized.
© 2012 EMC Publishing, LLC
Chapter 7
Processing Business DataChapter 7
Processing Business Data
The Replace() String method can be used to find and replace the $ and any commas with empty strings before converting the string using the Val() function.
The TrimEnd() String method can be used to remove the % before converting the string using the Val() function.
Slide 6
© 2012 EMC Publishing, LLC
Slide 7
Chapter 7
The ListBox ControlChapter 7
The ListBox Control
(Name) should begin with lst.
Items is used to add a set of strings to the box.
Sorted is set to True to display the list items in alphabetical order.
SelectedItem is the selected item.
SelectedIndex is the index of the selected item.
© 2012 EMC Publishing, LLC
Slide 8
Chapter 7
The ListBox Control Class Methods
Chapter 7
The ListBox Control Class Methods
Items.Add() is used to add an item to a list box at run time.
Items.Remove() is used to delete a specified item from the list box.
Items.Clear() deletes the contents of the list box.
© 2012 EMC Publishing, LLC
Slide 9
Chapter 7
The ComboBox ControlChapter 7
The ComboBox Control
(Name) should begin with cbo.
Items is used to add a set of strings to the box.
Text is the text displayed in the text box of the combo box.
Sorted is set to True to display the list items in alphabetical order.
SelectedItem is the selected item.
SelectedIndex is the index of the selected item.
© 2012 EMC Publishing, LLC
Slide 10
Chapter 7
The ComboBox Control Class Methods
Chapter 7
The ComboBox Control Class Methods
Items.Add() is used to add an item to a combo box at run time.
Items.Remove() is used to delete a specified item from the combo box.
Items.Clear() deletes the contents of the combo box.
© 2012 EMC Publishing, LLC
Slide 11
Chapter 7
Windows Application StandardsChapter 7
Windows Application Standards
© 2012 EMC Publishing, LLC
Chapter 7
Windows Application StandardsChapter 7
Windows Application Standards
The object with focus( contains insertion point/prompt ) will receive the user input from the keyboard.
An access key is the key pressed while holding down the Alt key to select an object. (&) is used in the Text property to define an access key. Access keys are not displayed until Alt is pressed.
A disabled object cannot be selected by the user. Enabled property is used.
A logical tab order can be set by the order in which objects are added to a form. This order can be changed by setting the TabIndex property of the objects ( first is 0 = initial focus ). Slide 12
© 2012 EMC Publishing, LLC
Slide 13
Math class trig methods include: Sin(angle) returns the sine of angle.
Cos(angle) returns the cosine of angle.Tan(angle) returns the tangent of angle.
The Sin(), Cos(), and Tan() methods require an argument in radians.
To convert from degrees to radians, use the Math class PI constant:
radians = (Math.PI / 180) * degrees
Chapter 7The Math Class Trigonometric
Methods
Chapter 7The Math Class Trigonometric
Methods
© 2012 EMC Publishing, LLC
Slide 14
Math class inverse trig methods include: Asin(num) returns the arcsine of num (in
radians)
Acos(num) returns the arccosine of num (in radians)
Atan(num) returns the arctangent of num (in radians).
Chapter 7The Math Class Inverse Trigonometric Methods
Chapter 7The Math Class Inverse Trigonometric Methods
© 2012 EMC Publishing, LLC
Slide 15
Math class logarithmic methods include: Log(num) returns the natural logarithm (base e)
of num.Log(num, base) returns the logarithm of num
in the specified base base.
Log10(num) returns the base 10 logarithm of num.
Exp(power) returns e raised to a power.Pow(num, power) returns num raised to the
power power.
The Math also includes the constant E which represents the base of natural logarithms.
Chapter 7The Math Class Logarithmic and
Exponential Methods
Chapter 7The Math Class Logarithmic and
Exponential Methods