Difference between revisions of "Visual Basic .net"
From ScienceZero
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==RS-232== | ==RS-232== | ||
==Datatypes== | ==Datatypes== | ||
| − | + | {| class="wikitable" | |
| − | + | ! VB type | |
| − | + | ! .net type | |
| − | + | ! Size | |
| − | + | ! Range | |
| − | + | |- | |
| − | + | | <code>Boolean</code> | |
| − | + | | <code>System.Boolean</code> | |
| − | + | | 4 bytes | |
| − | + | | True or False | |
| − | + | |- | |
| − | + | | <code>Byte</code> | |
| − | + | | <code>System.Byte</code> | |
| − | + | | 1 byte | |
| − | + | | 0 to 255 (unsigned) | |
| − | + | |- | |
| − | + | | <code>Char</code> | |
| − | + | | <code>System.Char</code> | |
| − | + | | 2 bytes | |
| − | + | | 0 to 65535 (unsigned) | |
| − | + | |- | |
| − | + | | <code>Date</code> | |
| − | + | | <code>System.DateTime</code> | |
| − | + | | 8 bytes | |
| − | + | | January 1, 1 CE to December 31, 9999 | |
| − | + | |- | |
| − | + | | <code>Decimal</code> | |
| − | + | | <code>System.Decimal</code> | |
| − | + | | 12 bytes | |
| − | + | | +/-79,228,162,514,264,337,593,543,950,335 with no decimal point; +/-7.9228162514264337593543950335 with 28 places to the right of the decimal; smallest non-zero number is +/-0.0000000000000000000000000001 | |
| − | + | |- | |
| − | + | | <code>Double</code> | |
| − | + | | <code>System.Double</code> | |
| − | + | | 8 bytes | |
| − | + | | -1.79769313486231E308 to -4.94065645841247E-324 for negative values; 4.94065645841247E-324 to 1.79769313486232E308 for positive values | |
| − | + | |- | |
| − | + | | <code>Integer</code> | |
| − | + | | <code>System.Int32</code> | |
| − | + | | 4 bytes | |
| − | + | | -2,147,483,648 to 2,147,483,647 | |
| − | + | |- | |
| − | + | | <code>Long</code> | |
| − | + | | <code>System.Int64</code> | |
| − | + | | 8 bytes | |
| − | + | | -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 | |
| − | + | |- | |
| − | + | | <code>Object</code> | |
| − | + | | <code>System.Object</code> (class) | |
| − | + | | 4 bytes | |
| − | + | | Any type can be stored in a variable of type <code>Object</code> | |
| − | + | |- | |
| − | + | | <code>Short</code> | |
| − | + | | <code>System.Int16</code> | |
| − | + | | 2 bytes | |
| − | + | | -32,768 to 32,767 | |
| − | + | |- | |
| − | + | | <code>Single</code> | |
| − | + | | <code>System.Single</code> | |
| − | + | | 4 bytes | |
| − | + | | -3.402823E38 to -1.401298E-45 for negative values; 1.401298E-45 to 3.402823E38 for positive values | |
| − | + | |- | |
| − | + | | <code>String</code> | |
| − | + | | <code>System.String</code> (class) | |
| − | + | | 10 bytes + (2 * string length) | |
| − | + | | 0 to approximately two billion Unicode characters | |
| − | + | |- | |
| − | + | | User-Defined Type (structure) | |
| − | + | | (inherits from <code>System.ValueType</code>) | |
| − | + | | Sum of the sizes of its members | |
| − | + | | Each member of the structure has a range determined by its data type and independent of the ranges of the other members | |
| − | + | |} | |
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==Strings== | ==Strings== | ||
Revision as of 09:11, 27 December 2009
Contents
Graphics
Files
Reading text files line by line:
Dim f1 As Long
dim filestring as string
f1 = FreeFile()
FileOpen(f1, My.Application.Info.DirectoryPath & "\filename.txt", OpenMode.Input)
Do Until EOF(f1)
- filestring=LineInput(f1)
Loop
FileClose(f1)
Note: My.Application.Info.DirectoryPath & "\filename.txt" may be replaced by "C:\some_path\file.txt"
Writing text files line by line:
Dim f1 As Long
f1 = FreeFile()
FileOpen(f1, My.Application.Info.DirectoryPath & "\filename.txt", OpenMode.Output
Print(f1, "This is line 1")
Print(f1, "This is line 2")
FileClose(f1)
Arrays
Threading / Parallel
Loops
Conditionals
Math
RS-232
Datatypes
| VB type | .net type | Size | Range |
|---|---|---|---|
Boolean
|
System.Boolean
|
4 bytes | True or False |
Byte
|
System.Byte
|
1 byte | 0 to 255 (unsigned) |
Char
|
System.Char
|
2 bytes | 0 to 65535 (unsigned) |
Date
|
System.DateTime
|
8 bytes | January 1, 1 CE to December 31, 9999 |
Decimal
|
System.Decimal
|
12 bytes | +/-79,228,162,514,264,337,593,543,950,335 with no decimal point; +/-7.9228162514264337593543950335 with 28 places to the right of the decimal; smallest non-zero number is +/-0.0000000000000000000000000001 |
Double
|
System.Double
|
8 bytes | -1.79769313486231E308 to -4.94065645841247E-324 for negative values; 4.94065645841247E-324 to 1.79769313486232E308 for positive values |
Integer
|
System.Int32
|
4 bytes | -2,147,483,648 to 2,147,483,647 |
Long
|
System.Int64
|
8 bytes | -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 |
Object
|
System.Object (class)
|
4 bytes | Any type can be stored in a variable of type Object
|
Short
|
System.Int16
|
2 bytes | -32,768 to 32,767 |
Single
|
System.Single
|
4 bytes | -3.402823E38 to -1.401298E-45 for negative values; 1.401298E-45 to 3.402823E38 for positive values |
String
|
System.String (class)
|
10 bytes + (2 * string length) | 0 to approximately two billion Unicode characters |
| User-Defined Type (structure) | (inherits from System.ValueType)
|
Sum of the sizes of its members | Each member of the structure has a range determined by its data type and independent of the ranges of the other members |
Strings
Finding text in a string:
InStr("this is a string", "is")
returns (character position number) 6. This function returns 0 when not found.
