# Visual Basic/VB6 Command Reference

This page aims to be a comprehensive command reference to the MS Visual Basic 6 programming language.

## String Manipulation
### Asc

Returns the number corresponding to the ASCII code for the first character of string
Usage
Asc(string)
string = string containing character as first letter whose ASCII code is to be found.
Example
code = Asc("Apple")
Here code will get value 65

### Chr

Returns a string character that corresponds to the ASCII code in the range 0-255. Reverse of the Asc function.
Usage
Chr(code)
code = ASCII code.
Example
char = Chr(97)
Here char gets value "a".

### Len

Returns the amount of characters in a given string or 0 for Empty.
Usage
Len(expression)
expression = a string or Empty
Example
mystring = InputBox("Enter a string to test") length = Len(mystring) MsgBox "Length of the string is " & length
e.g. where mystring is "Hello", length will be 5.

### Left

Returns a given number of characters from the left hand side of a string
Usage
Left(string,x)
string = string to use x = number of characters
Example
mystring = InputBox("Enter a string") mystring = Left(mystring, 4) MsgBox "First four characters of your input are " + mystring
e.g. where the input mystring is "Hello", the output mystring will be "Hell"

### Right

Returns a given number of characters from the right hand side of a string
Usage
Right(string, x)
string = string to use x = number of characters
Example
mystring = InputBox("Enter a string") mystring = Right(mystring, 4) MsgBox "Last four characters of your input are " + mystring
e.g. where the input mystring is "Hello", the output mystring will be "ello"

### Mid (Function)

Returns a given number of characters from the middle of a string
Usage
Mid(string, start, length)
string = string to use start = character to start at (1 is the first character) length = number of characters
Example
mystring = InputBox("Enter a string") mystring = Mid(mystring, 2, 3) MsgBox "The second, third, and fourth characters of your input are " & mystring
e.g. where the input mystring is "Hello", the output mystring will be "ell"

### Mid (Statement)

Sets a given number of characters in the middle of a string equal to the same number of characters from the beginning of another string
Usage
Mid(mystring, start, length)
mystring = the string to take characters from start = character to start at (1 is the first character) length = number of characters
Example
mystring = InputBox("Enter a string") Mid(mystring, 2, 3) = "abcd" MsgBox "Your string with abc as the second, third, and fourth characters of your input are " + mystring
e.g. where the input mystring is "Hello", the output mystring will be "Habco"

### Trim

Removes leading and trailing spaces from a string
Usage
Trim(string)
string = string to use
Example
mystring = Trim(mystring)
e.g. where the original value of mystring was " Hello ", the new value of mystring will be "Hello".

### LCase

Converts a string to lowercase
Usage
LCase(string)
string = string to use
Example
mystring = LCase(mystring)
e.g. where the original value of mystring was "HELLO", the new value of mystring will be "hello".

### UCase

Converts a string to uppercase
Usage
UCase(string)
string = string to use OR character
Example
mystring = UCase(mystring)
e.g. where the original value of mystring was "Hello", the new value of mystring will be "HELLO".

### String

Creates a string with the specified length of the specified character
Usage
String(length, character)
length = length of string character = character to fill string with
Example
mystring = String(5,"a")
e.g. the new value of mystring will be "aaaaa".

### Space

Creates a string with the specified length of space
Usage
Space(length)
length = length of string
Example
mystring = Space(5)
e.g. the new value of mystring will be " ".

### StrConv

Returns a converted string as specified.
Usage
StrConv(string, conversion,LCID)
string = string to use conversion = case to convert the string to (lowercase: vbLowerCase, uppercase: vbUpperCase, proper case (first letter in caps): vbProperCase) LCID = optional. The LocaleID, if different than the system LocaleID.
Example
mystring = StrConv(mystring, vbProperCase)
e.g. where the original value of mystring was "HELLO", the new value of mystring will be "Hello".

## Mathematical Functions
### Abs

Returns the absolute value of a number
Usage
Abs(number)
Example
msgbox "The absolute value of -4 is " & abs(-4)
Important note!
The Abs function only accepts numbers. Non-numeric values generate an error.

### Cos

Returns the cosine of a number
Usage
Cos(integer)
Example
msgbox "The cosine of 4 is " & cos(4)
Important note!
The input angle for all VB trigometric functions should be in radians. To convert degrees to radians, multiply degrees by pi / 180.

### Sin

Returns the sine of a number
Usage
Sin(integer)
Example
msgbox "The sine of 4 is " & sin(4)
Important note!
The input angle for all VB trigometric functions should be in radians. To convert degrees to radians, multiply degrees by pi / 180.

### Tan

Returns the tangent of an angle
Usage
Tan(integer)
Example
msgbox "The tangent of 4 is " & tan(4)
Important note!
The input angle for all VB trigometric functions should be in radians. To convert degrees to radians, multiply degrees by pi / 180.

### Val

Returns the numeric value of a string
Uses "." as decimal separator. ( It does not depend on the Regional Settings )
Usage
Val(string)
Example
Val("5")
The return value will be 5
Val("10.6")
The return value will be 10.6
Val("Hello World")
The return value will be 0 (zero)
txtOutput.Text = Val(txtNumber1.Text) * Val(txtNumber2.Text)
The text box txtOutput will contain the product of the numbers in the txtNumber1 and txtNumber2 text boxes. If either of the text boxes contains a value that cannot be evaluated to a number then the output will be 0 (zero).

### Rnd

Returns a floating point number less than 1 but greater than or equal to 0.
Usage
Rnd[(number)]
You can change the seed the random number generator uses by providing a value as a parameter e.g. Rnd(500) will use the number 500 as the seed in generating random numbers.
* If you provide a value less than zero then the same number will be returned by the Rnd function
* A value of zero will return the most recently generated random number.
* Providing no value will generate the next random number in the sequence.
* Providing a positive number will generate the next random number in the sequence using number as a seed.
Example
myvar = Rnd * 10
myvar will become a random number between 0 and 10.
myvar = (Rnd * 15) + 25
myvar will become a random number between 25 and 40.
myvar = (Rnd(12345) * 50) - 25
myvar will become a random number between -25 and 25 and 12345 will be used as the seed to generate this number.

### Int

Returns the integer portion of a number.
Usage
Int(n)
Where n is the number to return
Example
Int(10)
Returns 10
Int(5.1)
Returns 5
Int(5.86)
Returns 5
MsgBox "The integer portion of " & myvar & " is " & Int(myvar) & "."
NOTE: No rounding will be performed, the decimal portion of the number will simply be removed. If you want to round a number to the nearest whole integer then use CInt. One interesting point to remember about CInt is that if the decimal portion of the number is exactly .5 then it will be rounded down if the number is odd and rounded up if it is even. For example CInt(1.5) and CInt(2.5) will both return 2.

## Input and output
### MsgBox

The MsgBox function displays a message in a dialog box, waits for the user to click a button, and returns an Integer value indicating which button the user clicked.
Syntax MsgBox(prompt[, buttons] [, title] [, helpfile, context])
The MsgBox function syntax has these parts:
| PART | DESCRIPTION |
| prompt | Required. String expression displayed as the message in the dialog box. The maximum length of prompt is approximately 1024 characters, depending on the width of the characters used. |
| buttons | Optional. Numeric expression that is the sum of values specifying the number and type of buttons to display, the icon style to use, the identity of the default button, and the modality of the message box. If omitted, the default value for buttons is 0 (which causes only an OK button to be displayed with no icon). |
| title | Optional. String expression displayed in the title bar of the dialog box. If you omit title, the application name is placed in the title bar. |
| helpfile | Optional. This argument is only applicable when a Help file has been set up to work with the application. |
| context | Optional. This argument is only applicable when a Help file has been set up to work with the application. |
Usage MsgBox(prompt[, buttons] [, title] [, helpfile, context]) or Response=MsgBox(prompt[, buttons] [, title] [, helpfile, context]) The integer value of the button selected will be placed into the Response variable.
Button Combinations vbOKOnly vbOKCancel vbAbortRetryIgnore vbYesNoCancel vbYesNo vbRetryCancel
Icon Display vbCritical vbQuestion vbExclamation vbInformation
Default Button vbDefaultButton1 vbDefaultButton2 vbDefaultButton3 vbDefaultButton4
Examples MsgBox "An error has occurred!",vbExclamation,"Error" Note that since the message is fixed, quotation marks have been used.
Response=MsgBox("Yes or no?",vbYesNo + vbQuestion,"Choose one") Note the parenthesis and how the vbYesNo and vbQuestion constants have been combined
MsgBox "An error has occurred on line " & lineno, vbExclamation, "Error"

### InputBox

Displays a simple input box for user to enter data
Usage
Variable=InputBox(Prompt,Title)
Variable = variable to which the input value will be stored Prompt = text displayed to the user in the input box Title = title of the input box
Examples
myint=InputBox("Enter a number","Enter a number")

## Date and Time
### Date

Returns or sets the current system date
Example
MsgBox "Today 's date is " & Date & "."

### Time

Returns or sets the current system time
Example
MsgBox "The time now is " & Time & "."
Sidenote: be wary of changing date and time in your program. Many other programs will depend upon the system's date and time being set correctly, so altering it could have a knock on effect. Use date and time changes sparingly, and notify the user if this is being done.

### Timer

Returns the number of seconds since midnight
Example
NumHrs=Int(Timer / 3600) MsgBox "Currently in hour " & NumHrs

### WeekdayName

Returns the name of a day of the week
Usage
WeekdayName(x,FirstDayOfWeek)
x = integer between 1 and 7 FirstDayOfWeek (OPTIONAL) = the day counted as the first in the week. The default is Sunday.
Example
DayName=WeekdayName(i,vbMonday)

## Miscellaneous
### IsNull

Returns true if an expression is null and false otherwise.
Example:

## File Handling
### Open

Open "" & namefile& ".dat" For Binary As #ff

## Selection

If... Then... Else... Performs selection based upon criteria. A cornerstone of any VB program.
'Usage'
Single Line Selection
Note that only one line can be used with this style of statement
Multi Line Selection
Using Else
Condition is a condition which must be met for the code within the statement to be executed. It can make use of the modifiers AND, NOT, OR and XOR (e.g. x=4 AND y > 6). See also the Examples section.

### Examples

Simple one-line selection:
Slightly more complex one-line selection, using the AND modifier to check two conditions at one time.
Simple multi-line selection. The code between the If... and EndIf statements will be executed only if the condition is met.
Using the Else statement. If the variable i is over 4, the program will exit the subroutine. Otherwise, it will go to the label SaveFile.
Two If... Endif statements are used, one nested within the other. If i is 6 or 7, the code between the inside If...Endif statements is executed. Then if i=7 the first message box will be shown; otherwise (i.e. if i=6) the other will be displayed. For both cases, the final message box will be shown. When nesting selection statements, it's often a good idea to indent them as shown here.

## References

* ↑ https://docs.microsoft.com/fr-fr/office/vba/language/reference/user-interface-help/chr-function
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