Visual Basic Commands

[jawadpk]

Visual Basic Commands

Here are the VB operators used to perform mathematical operations on one or more variables. Aside from the normal multiply/add/substract and divide, you will find the AND, OR, Not Equal, MOD and Integer Division operators very useful.


PART1 :


/ - Normal division
\ - Integer division (truncates the answer)
^ - Exponentiation operator
* - Multiply
+ - Plus
- - Minus
= - Equal
> - Greater Than
< - Less Than
<> - Not Equal
>= - Greater than or equal
<= - Less than or equal
AND - Defines a boolean value that is the AND of two values result = expression1 AND expression2
OR - Defines a boolean value that is the OR of two values result = expression1 OR expression2
XOR - Defines a boolean value that is the exclusive OR of two values result = expression1 XOR expression2
NOT - Defines an opposite boolean value A = NOT B
EQV - Performs a logical equivalence on two expressions (result is true if both expressions are true) result = expression1 EQV expression2
IMP - Performs a logical implication on two expressions result = expression1 IMP expression2
IS - Determines if 2 variables reference the same object result = object1 IS object2
LIKE - Determines if one string matches a pattern result = string LIKE pattern
MOD - Returns the integer remainder of a division i = 27 MOD 5
Math
VB also provides built-in functions which can act on variables. Most are self-explanatory. In my experience, the VAL, RND, and ROUND functions are among the most valuable, so be sure to pay close attention to them!
Round - Rounds a number to a selectable number of decimal places result = round ( tempvariable,2 )
Val - Returns the numerical content of a string result = Val ("123.4")
Int - Returns an integer by truncating (different than Fix) i = int ( tempvariable )
Fix - Returns an integer by truncating (different than Int) i = fix ( tempvariable )
Hex - Returns the hexadecimal value of any number temp$ = hex ( tempvariable )
Oct - Returns the octal value of any number temp$ = oct ( tempvariable )
Tan - Returns the tangent of an angle tempvariable1 = tan ( tempvariable2 )
Rnd - Returns a random number between 0 and 1 tempvariable1 = rnd
Randomize - Initializes the Rnd function so it gives different answers each time randomize
Sgn - Returns the sign of a number i = sgn ( tempvariable )
Sin - Returns the sine of an angle tempvariable1 = sin ( tempvariable2 )
Cos - Returns the cosine of an angle tempvariable2 = cos ( tempvariable )
Abs - Converts a number to a positive value i = abs ( tempvariable )
Sqr - Returns the square root of a number tempvariable1 = sqr ( tempvariable2 )
Log - Returns the base 10 logarithm of a number tempvariable1 = log ( tempvariable2 )
Atn - Returns the arctangent of an angle tempvariable1 = atn ( tempvariable )
Partition - Sort of an oddball function but segregates values according to ranges
Type Conversions - A variety of conversion functions
CBool, CByte, CCur, CDate, CDbl, CDec, CInt, CLng, CSng, CStr, CVar
Strings
In my experience these functions are used more than just about any of the other VB built-in functions. The FORMAT, MID, and INSTR functions are incredibly powerful and I use them extensively. If you don't understand what they are, they are worth the time to figure out! The LEN and CHR functions are also valuable as are the variations on the trim and case functions.
Left - Returns the left n characters of a string temp$ = left$ ( teststring$, 4 )
Right - Returns the right n characters of a string temp$ = right$ ( teststring$, 4 )
Trim - Removes leading and trailing spaces of a string temp$ = trim$ ( teststring$ )
LTrim - Removes only the leading spaces of a string temp$ = ltrim$ ( teststring$ )
RTrim - Removes only the trailing spaces of a string temp$ = rtrim$ ( teststring$ )
UCase - Makes all characters upper case temp$ = ucase$ ( teststring$ )
LCase - Makes all characters lower case temp$ = lcase$ ( teststring$ )
Mid - Returns n characters from a string, starting a any position temp$ = mid$ ( teststring$, 1, 4 )
Len - Returns the length of a string (how many characters it has) temp$ = len ( teststring$ )
LSet - Positions a string inside another, flush to the left temp$ = lrset ( teststring$ )
RSet - Positions a string inside another, flush to the right temp$ = rset$ ( teststring$ )
Format - Returns a string formatted according to a user-defined format temp$ = format$ ( teststring$, "####.0" )
String - temp$ = left$ ( teststring$, 4 )
Chr - Returns the string representation of a number temp$ = str$ ( 32 )
Asc - Returns the ASCII code of a single character temp$ = asc ( "A" )
Space - Returns n spaces temp$ = space$ ( 15 )
Instr - Determines if one string is found within a second string i = Instr (starthere, string1, string2)
InStrRev - Determine if one string is found in a second, starting at the end i = InStrRev (string1, string2, start)
StrComp - Compares two strings result = StrComp (string1, string2)
StrConv - Converts the case of a string's characters StrConv (string, vbuppercase)
StrReverse - Reverses character order in a string StrReverse (string1)
Replace - Replaces each occurrence of a string Replace (bigstring, searchstring, replacementstring)
FormatCurrency - Returns a string using a currency format FormatCurrency(var1, 2)
FormatDateTime - Returns a date or time expression FormatDateTime("3/2/99",vbShortTime)
FormatNumber - Returns a number formatted according to a variety of options FormatNumber(var1, 2)
FormatPerCent - Returns a number formated as a percent FormatPerCent(var1, 2)
Arrays

[jawadpk]

Part 2

Every programmer eventually uses arrays. Mostly they're pretty easy to understand. Take note, however, that you can resize an array with REDIM without losing the data. For details, see the PRESERVE keyword in the HELP entry on REDIM. If you use the LBound/UBound in your code instead of hard-coding the dimension of the array, you can later change the size of the array without touching your code!
Option Base - Determines whether the lowest range of an array is 0 or 1 option base 1
Erase - Erases all values of an array erase (arrayname)
Dim - Creates an array dim arrayname(25)
Redim - Resets the bounds of an array (has option to save values) redim arrayname(28)
UBound - Returns the upper dimension of an array i = ubound (arrayname)
LBound - Returns the lower dimension of an array i = lbound (arrayname)
Filter - Returns a subset of an array based on a filter Filter (inputarray, searchstring)
Array - Yes, there is a function called array. It returns an array that has been filled with data from a list. It allows you to put the actual data values in the code to avoid having the user input it or to avoid having to read it from a file ArrayName = Array (10, 20, 30)
Join - Concatenates strings within an array File Handling (Generic)
While VB is working on a better approach (FileSystemObject), the built-in file handling statements are still the only way to access data other than through the VB database capabilities. Your skills in this area can make or break your ability to work with various formats. The OPEN/CLOSE statements are critical to success, but the LOF, EOF, and LEN functions are used even more often! It's also a given that you'll use the DIR function regularly.
Dir - Returns a filename that matches a pattern temp$ = Dir ("*.*")
CurDir - Returns the current directory temp$ = CurDir
MkDir - Creates a directory mkdir ( "newdirectoryname" )
ChDir - Changes the current directory to a new location chdir ( "newdirectoryname" )
ChDrive - Changes the current drive ChDirve "A"
RmDir - Removes the indicated directory rmdir ( "directoryname" )
Freefile - Returns an unused file handle i = freefile
Open - Opens a file for access, locking it from other applications open "filename" for input as #1
Close - Closes a file so that other applications may access it close #1
LOF - Returns the length of a file in bytes i = lof ( #1 )
EOF - Returns a boolean value to indicate if the end of a file has been reached statusvariable = eof ( #1 )
Name As - Renames a file name "filename1" as "filename2"
Kill - Deletes a file kill "filename"
Fileattr - Returns attribute information about a file i = int ( tempvariable )
GetAttr - Returns attributes of a file or directory i = GetAttr("c:\windows emp")
SetAttr - Sets the attributes of a file SetAttr pathname, vbHidden
Reset - Closes all disk files opened by the OPEN statement Reset
FileDateTime - Returns data file was created or last edited FileDateTime ( filename )
FileLen - Returns length of file in bytes FileLen ( filename )
FileCopy - Copies a file to a new name FileCopy sourcefile, destinationfile
Lock - Controls access to a part or all of a file opened by OPEN Lock #1
UnLock - Restores access to a part or all of a file opended by OPEN UnLock #1
Width # - Set the output line width used by the OPEN statement Width #2, 80
File Handling - ASCII-specific
While VB is working on a better approach (FileSystemObject), the built-in file handling statements are still the only way to access data outside of a data base. Your skills in this area can make or break your ability to work with various formats. The OPEN/CLOSE statements are critical to success, but the LOF, EOF, and LEN functions are necessary to build useful code.
Line Input - Reads an entire line of ASCII text line input #1, tempvariable$
Write - Puts data in a file, with separators for the data write #1, tempvariable$

Print - Puts data in a file with no separators print #1, tempvariable$ Spc - Used in a print statement to move a number of spaces Print #2, var1; spc(15); var2
Tab - Used in a print statement to move to TAB locations Print #2, var1; Tab(20); var2
File Handling - Binary-specific
VB also support features which allow you to access a file on a byte-by-byte basis. The good thing about it is that you have more control, the bad thing is that you may have to write more code. Generally, a programmer will use the option (ASCII or Binary access) according to the least code he has to write. For binary access the Get/Put are equivalent to the Line Input and Print functions used in ASCII text file access. The big difference between the two is that binary access will read (Get) an exact number of bytes of data, and the reading can start at any byte within the file.
Get - Reads data from a file get #1, anyvariable
Put - Puts data into a file put #1, anyvariable
Seek - Moves the current pointer to a defined location in a file seek #1, 26
Input input #1, anyvariable
Loc - Returns current position with an open file i = Loc(#2)
Declarations
I probably get more questions about the functions in this section than about any other group. In general, the concepts are pretty simple, but the details of getting it exactly right can cause even experienced programmers trouble. Focus on understanding Dim/ReDim/Public/Private/Sub/Function/Type and Set. However, they're all useful at times, so bear down and commit these to memory. I'll try to add more text and tips on these than I have on the others.
Dim - Used to define a variable as a certain type i = dim i as integer, r as single
You can use the Option Explicit to make sure that VB forces you to declare every variable you use. DIM is that simplest way to declare a variable
ReDim - Used to change the dimensions of a dynamic array redim arrayname(37)
Don't be afraid of this one. You can use ReDim to create an array whose size grows by 1 every time you want to add a number to it. Then, the UBound tells you how many numbers you've added.
Static - Establishes a procedure variable which keeps its value between calls static i as integer
For example, if you want to keep track of how many times you've been in a procedure, set a counter as STATIC and increment it by one for each visit to the procedure. It will never go away until the program is terminated.
Public - Creates a variable which can be accessed outside its own procedure public i as integer
Even if you're the only programmer writing code in your application, use of Private vs Public will help catch errors if you inadvertently try to access an out-of-scope variable
Private - Creates a variable that can be read only in its own procedure or module, according to where the declaration took place. private i as integer
Use this as often as possible to avoid unnecessary exposure of your variables to coding mistakes.
Sub - Defines a procedure which can execute a block of code Sub NewProcedure (var1 as integer, var2 as string)
Be sure to check out HELP for how to handle Sub arguments. There are more questions and mistakes made concerning the use of arguments than just about anything else I've seen.
Function - Declares a procedure which can return a value Function NewFunction (var1 as integer, var2 as string) as SINGLE
This is actually the most versatile of the Sub/Function procedure types. It can do anything a Sub can do as well as returning a value for use in an expression.
Call - Transfers control to a Sub or Function (is optional) Call Procedure 1
Since the use of CALL is optional, forget you ever saw it CallByName - Executes a method of an object or set/returns a property CallByName(form1,procedurename,vbMethod)
The really cool thing about this is that you don't have to hardcode a procedure call. Just use a string variable with the name of the procedure to call. Option Explicit - Instructs VB to force an explicit declaration of all variables Option Explicit
Set up the VB IDE to automatically include this in all projects.
Option Compare - Instructs VB on how to make string comparisons Option Compare Binary
This can add case-insensitivity for those times when you don't want to hard-code it Option Private - Prevents a module's content from being referenced outside a project. Option Private Module
Generally doesn't apply to most VB applications. If you find a good use for it let me know. Property Get - Declares how to get the value of a property Property Get Name()

[jawadpk]

Part 3

You won't use this much until you get into creating classes of your own Property Let - Declares how to assign a value to a property Property Let Name() You won't use this much until you get into creating classes of your own Property Set - Declares how to set a variable reference to an object
You won't use this much until you get into creating classes of your own
Set - Assigns an object reference to a variable Set X = form1.txtInputFromUser
Very useful for making code more readable or simply to cut down on how much typing you have to do!
Let - Precedes assignment of a value to a variable Let i = 3
It's optional, no one uses, so forget you ever saw it
Type...End Type - Creates a user defined part type which consists of standard VB data types
type anytypename
one as string
two as integer
three as boolean
End Type
This is a really excellent way to keep several kinds of data under one variable name. Plus, you can PUT or GET a user-defined type with a single line of code. Const - Creates a variable whose value is fixed
const anyname
Basically, use this to give easy to remember names to values. For example, suppose you use the value 37.2 a lot in your code, then if you put CONST MyAge = 37.2 in your code you'll be able to insert the MyAge where the 37.2 should have gone. Easier to type and easier to read. Also, you can chane the value of the constant by changing only the declaration line of code, rather than searching out every place the value was used! Declare - Used to define a procedure that exists in another file declare functionname (arg1 as integer, arg2 as string) as integer ArrayName = Array (10, 20, 30)
Implements - Specifies a class to be implemented in a module Friend - Allows procedure to be callable from modules outside the class

GetObject - Return a reference to an ActiveX component
CreateObject - Creates and returns a reference to an ActiveX object
GetAutoServerSettings - Returns information about the state of an ActiveX component's registration. Enum - Declares a type for an enumeration
Event - Declares a user-defined event
TypeName - Returns the type of data in a variable
VarType - Returns the type of data in a variable
DefType - Sets the default data type of variables DefInt A-Z
IS - A variety of data type or status checking options
IsArray, IsBindable, IsBroken, IsDate, IsDirty, IsEmpty, IsError, IsMissing, IsNull, IsNumber, IsObject, IsReady, IsRootFolder
Date/Time
These functions are pretty self-explanatory so I've not added any extra comments to them.
Date - Gets the current date
Time - Gets the current time
Now - Gets the current date and time
Timer - Returns the number of seconds since midnight
DateAdd - Adds a time interval to a date
DateDiff - Returns how many time intervals there are between two dates
DateSerial - Returns the month/day/year
DateValue - Returns the date
Year - Returns the current year
Month - Returns the current month (integer)
MonthName - Returns the text of the name of a month
Day - Returns the current day
Hour - Returns the current hour
Minute - Returns the current minute
Second - Returns the current second
TimeSerial - Returns a date with the hour/minute/second
TimeValue - Returns the time
WeekDay - Returns the current day of the week (integer)
WeekDayName - Returns the text of a day of the week Miscellaneous
In this list you'll find some of the features of VB about which I get a lot of email questions! The MsgBox is easily the most used of the bunch. It handles all of the "Y/N" queries to your user so get to know it well. Also, the DoEvents, Shell, and Command functions are indispensable in certain occasions so make sure you know when they should be used.

MsgBox - A built-in dialog box that gives a message and allows a user input i = msgbox "Read this!", vbokonly, "Test Message"
DoEvents - Allows VB to complete pending tasks doevents
Shell - Executes a 2nd program from within the current program shell "notepad.exe"
Note - VB does not wait for the Shell'd program to quit before executing the next line of code! Command - Gives any text that followed a VB .EXE execution command temp$ = command Environ - Returns the system environmental space content temp$ = environ
Beep - Makes the computer beep once.
beep
InputBox - A built-in dialog box that allows entry of a text string inputbox "Input a value!", 5
AddressOf - Provides an entry point for an external program to use a procedure AddressOf ( procedurename )
AppActivate - Activates an applications window AppActivate ( windowtitle )
RaiseEvent - Fires an event declared at module level RaiseEvent ProcedureName
Load - Load an object load form1
Unload - Unload an object Unload form1
LoadPicture - Load a picture into a control property form1.picture = loadpicture (filename)
SavePicture - Save a picture to a file SavePicture(form1.picture,filename)
LoadResData - Load the data from a resource file LoadResData(index,format)
LoadResString - Load a string from a resource file LoadResString(index,format)
SendKeys - Send keys to another app as though they were from the keyboard Sendkeys {DOWN}
QBColor - Returns a value corresponding to the original QB values 0-15 form1.backcolor = QBcolor (12)
RGB - Returns a color value by inputting the red, green, and blue parts form1.backcolor = RGB (12,128,256)
Me - Refers to the current object, usually the active form print Me.caption
Registry
I've never quite understood why Microsoft got away from the use of an INI file. The ability to use a simple text editor to resolve problems with a program's settings was a key feature about INI files. Also, no matter how Windows crashed, the INI file was protected.
VB has made it incredibly easy to access values in the registry. The following VB functions are simple to use and there's hardly any excuse for not taking advantage of them. One thing to remember is that the registry save strings so if you're saving or reading numeric information then may have to do some string manipulation with the results.
GetSetting - Get a value from the Registry

[billal_jaan]

Nice

[Fatima Iqbal]

Move From
General Discussion

[annus]

salaam sir mujhe .exe or .dll file k bare m study krni ha k .exe rewrite ho sakti ha or .dll file ? or .dll file kia kam krti hai kis liye use hoti ha? or hum isko kis tarha write kare?

[allaudin]

.exe is executable windows file . you cannot overwrite it, and for dll read following :
Dynamic Link Libraries (DLL)s are like EXEs but they are not directly executable. They are similar to .so files in Linux/Unix. That is to say, DLLs are MS's implementation of shared libraries.

DLLs are so much like an EXE that the file format itself is the same. Both EXE and DLLs are based on the Portable Executable (PE) file format. DLLs can also contain COM components and .NET libraries.

What does a DLL contain?

A DLL contains functions, classes, variables, UIs and resources (such as icons, images, files, ...) that an EXE, or other DLL uses.

Types of libraries:

On virtually all operating systems, there are 2 types of libraries. Static libraries and dynamic libraries. In windows the file extensions are as follows: Static libraries (.lib) and dynamic libraries (.dll). The main difference is that static libraries are linked to the executable at compile time; whereas dynamic linked libraries are not linked until run-time.

More on static and dynamic libraries:

You don't normally see static libraries though on your computer, because a static library is embedded directly inside of a module (EXE or DLL). A dynamic library is a stand-alone file.

A DLL can be changed at any time and is only loaded at runtime when an EXE explicitly loads the DLL. A static library cannot be changed once it is compiled within the EXE. A DLL can be updated individually without updating the EXE itself.

Loading a DLL:

A program loads a DLL at startup, via the Win32 API LoadLibrary, or when it is a dependency of another DLL. A program uses the GetProcAddress to load a function or LoadResource to load a resource.
NOTE : Before posting anything please do search on google .