lesson 4 visual basic data
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ANALYZINGVISUAL BASIC DATA
VISUAL BASIC OPERATORS• Like other programming languages
may it be text oriented or object oriented type like Visual Basic, it uses five basic arithmetic operations which are addition, subtraction, multiplication, division and exponentiation.
The following are symbols for declaring specific operationsMathematical Operation
Operator or Symbol
Mathematical Notation
Example Result
Addition + a+b 17+2 19
Subtraction - a-b 2-17 -15
Multiplication * a*b 2*17 34
Division / a/b 17/1 17
Exponentiation ^ a^b 7^2 49
+ or & String Concatenations
String1 + String2 or String1 & String2
“Hello” + “World”
Hello World
mod Reminder of division
a mod b 19mod3 1
The following are symbols for declaring specific operations• Visual Basic follow the precedence of the
formula like in Math wherein if follow the rules of EMDAS.
• Use parenthesis to alter the precedence followed by EMDAS. Expressions inserted inside a parenthesis will be executed first before the other expressions.
RELATIONAL OPERATORS
Operators Description Mathematical Notation
Example Result
> Greater than a>b 25>2 True
< Less than a<b 25<5 False
>= Greater than or equal to
a>=b 83>=75 True
<= Less than or equal to
a<=b 83<=75 False
< > Not equal a< >b Password<> computer
True
= Equal a = b Password = computer
False
LOGICAL OPERATORS
Operators Description Example ResultOR It will retrieve true value if the
operand are true.(25>3) OR (3<5) True
AND It will retrieve true value only if both operands are true
(25>3) AND (3<5) True
XOR Both must not be true meaning only one side should hold true value
(25>3) XOR (3<5) False
NOT Reverse true side NOT (2=2) False
Example
KINDS OF DATA TYPES1. Numeric – a data type that holds whole numbers.
Two Categorya. Integers – which are whole numbers and without
decimal.b. Decimal – holds numbers with decimal points
that usually represent fractional values like 3.1426, -22, etc.
.
KINDS OF DATA TYPESSeven Numeric Data Types
Type Storage RangeByte 1 byte 0 to 255
Integer 2 bytes -32,768 to 32,768
Long 4 bytes -2,147,483,648 to 2,147,483,648
Single 4 bytes -3.402823E+38 to -1.401298E-45 or1.401298-45 to 3.402823E+38
Double 8 bytes -1.79769313486232E+308 to -4.94065645851247E-324 or
4.94065645851247E- to 3241.79769313486232E+308
Currency 8 bytes -922,337,203,685,477.5808 to 922,337,203,685,477.5808
Decimal 12 bytes +/-79,228,162,514,264,337,593,543,950,335
This if no decimal.+/-
79,228,162,514,264,337,593,543,950,335
KINDS OF DATA TYPES2. Nonnumeric – usually consists of characters, date,
Boolean data or variant data types.Example:a. String – is a series of characters which may
range from zero or more characters. It may hold numeric characters but it is never used for calculations.
b. Date – used for dates.c. Boolean data – only holds two values, yes or no,
true or false.d. Variant – data that cam hold any kinds of data
except for fixed length strings.
KINDS OF DATA TYPES
Seven NonNumeric Data TypesType Storage Range
String as Fixed length 1 byte 1 to 65,400 characters
String as Variable 2 bytes 0 to 2 billion characters
Date 4 bytes January 1, 1000 to December 31, 9999
Boolean 4 bytes True or False
Object 8 bytes Any embedded objects
Variant (numeric) 8 bytes Any value as large as double
Variant(text) 12 bytes The same as variable length string
VARIABLESVariables are inserted as code statements. These are temporary named storage area inside the program’s memory that will hold data. Variable names are important in a program; they hold a value for as long as the user doesn’t change the value. Unlike with a control (txtname.text=“Visual Basic) which does not hold values for long. This means that variables are memory locations which are used to store values temporarily.
VARIABLE DeclarationsVariables declarations depend on how and where they are declared. Variables can be declared as explicit declaration or option implicit.Option Explicit Declaration - tells Visual Basic that the rest of the code in a module is to declare all variables before they are used.Option Implicit Declaration – easier way of declaring a variable however it is not advisable to use. This is a type where you don’t need to declare a variable as Visual Basic automatically assign a variable type.
EXPLICIT Declarations
It is advisable to declare all variables before they are used in a program. Using the DIM statement to declare variables by assigning them a name and a data type. Below is the format of the DIM statement in a variable declaration.
Dim Varname as Data TypeVarname is the name you assign to a variable and theData type is the type of data that the variable will hold.
EXPLICIT DeclarationsLike giving names in a control, variables also used prefixes in assigning names to them. Below are the variable name prefixes that describe variables data type.
Prefix Data Type Examplebln Boolean blnoptionbyt Byte Bytagecur Currency Curitrdte Date Dteinventorydbl Double Dbllongnumbersint Integer Intyearlevellng Long LngspeedObj Object ObjpresentationSng Single SngincomeStr String Strnamevnt variant vntnum
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