【英文】VB的数据类型

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Introduction

Notes on VB Data Types

Data Types

  • Variant

  • Primitive Types

    • Numeric Types
      • Integer
        • Integer *
        • Long
      • Real Types
        • Single *
        • Double
      • Currency
      • Byte
    • String Types
      • Fixed-length String (String*n)
      • Variable-length String (String) *
    • Boolean *
    • Date *

  • Composite Types

    • User-defined Types (Object)
    • Arrays

Strings

  • Strings can be fixed-length (String*n) (where n is the length of the string) or variable-length (String)
  • Strings are enclosed in double quotation marks ""
  • The length of a string is the number of characters in the string
  • A string with a length of 0 is called an empty string and is represented by ""

Integer

  • Integer consists of Integer and Long
  • Integer occupies 2 bytes in memory
  • Long occupies 4 bytes in memory
  • Decimal numbers are composed of digits 0 to 9
  • Octal numbers are composed of digits 0 to 7. To represent octal numbers, use the prefix &, &O, &o, &0
  • Hexadecimal numbers are composed of digits 0 to 9 and letters A to F. To represent hexadecimal numbers, use the prefix &H, &h

Real Types (Floating Point Types)

  • Real types consist of Single and Double
  • Real numbers can be represented in two forms
    • Decimal form: 3.14
    • Exponential form: 0.12E+5 (0.12×105)
  • Single occupies 4 bytes in memory and can represent up to 7 significant digits
  • Double occupies 8 bytes in memory and can represent up to 15 significant digits

Byte

  • Byte is an unsigned integer that occupies 1 byte in memory, with a value range of 0 to 255

Currency

  • Currency occupies 8 bytes in memory and represents decimal numbers
  • Currency is precise to 4 decimal places

Boolean

  • Boolean occupies 2 bytes in memory
  • Boolean can have only two values: True and False
  • When a Boolean value is converted to a numeric type: True is converted to -1 and False is converted to 0
  • When a numeric value is converted to a Boolean type: nonzero values are converted to True and 0 is converted to False

Date

  • Dates are enclosed in double pound signs ##
  • Dates can represent the following ranges:
    • Year, month, and day range: January 1, 100 to December 31, 9999
    • Time range: 0:00:00 to 23:59:59
      For example: #1 Jan,17#, #2017-12-1 10.:30:00 am#

Variant

  • Variant is the default type for variables that are not declared

Type Suffix

  • Type suffixes include %, &, !, #, $, @
  • When declaring a variable and omitting the data type, you can add a type suffix to the end of the variable name to define the data type
Variable Name with Suffix Data Type
VariableName% Integer
VariableName& Long
VariableName! Single
VariableName# Double
VariableName@ Currency
VariableName$ String

Default Values

  • When a variable with a specified data type is defined but not assigned a value, it takes on the default value
Data Type Default Value
Integer 0
Boolean False
Date 1/1/0001 12:00:00 AM
String ""
Variant Empty

Completion

References

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