Difference between revisions of "Number"

Revision as of 21:29, 30 March 2009

This page covers Number datatype tips & tricks.

How to combine two numbers to one and vice versa

To combine two numbers into one, use the next function

   nCombined = VisNumberMakeLong( nValue1, nValue2)

You can find this function in vtmisc.apl
Beware that the two input parameters must have a value between 0 and 65535.

To get the two values back from the combined number

   Set nValue1= SalNumberLow( nCombined )
   Set nValue2= SalNumberHigh( nCombined )

How to convert a number to string using prefixed zeros

An easy way to do that is using this function

   sResult = SalFmtFormatNumber( nValue, sPicture )

So if you want to have a string with 5 characters and if nValue results in less characters and should be prefixed with zeros

   Set nValue = 12
   Set sResult = SalFmtFormatNumber( nValue, "00000" )      ! Picture parameter has 5 zeros specified

   ! sResult has the value "00012"

An alternative way to define a number in boolean expressions

Look at the next piece of code

   If bOk = TRUE
      Set nValue = 1
   Else
      Set nValue = -1

It can be rewritten using one line of code using this function from vtmisc.apl

   nResult = VisNumberChoose( bExpression, nTrueNumber, nFalseNumber )

So the If/Else construction above can be rewritten to

   Set nValue = VisNumberChoose( bOk = TRUE, 1, -1 )

See also String : An alternative way to define a string in boolean expressions

How to convert from one base to another (eg decimal to hexadecimal to binary)

Developers familiar with the C(++) language will probably know conversion functions like itoa and strtol.
The itoa function (integer to ascii) is able to convert/format a decimal integer number to a given base (eg hexadecimal, binary, octal etc).
The function strtol does the opposite, converting a base to decimal.

These functions are also available to other programming languages with the MSCRT library (C runtime).
So also for TD.

First declare these external functions (below the declarations for TD versions prior to TD5.x) :

Library name: MSVCRT.dll
   Function: _itoa
      Export Ordinal: 0
      Returns
      Parameters
         Number: INT
         Receive String: LPSTR
         Number: INT
   Function: strtol
      Export Ordinal: 0
      Returns
         Number: LONG
      Parameters
         String: LPCSTR
         Number: LPVOID
         Number: INT

Below the declarations for TD 5.x versions :

Library name: MSVCRT.dll
   Function: _itow
      Export Ordinal: 0
      Returns
         String: LPWSTR
      Parameters
         Number: INT
         Receive String: LPWSTR
         Number: INT
   Function: wcstol
      Export Ordinal: 0
      Returns
         Number: LONG
      Parameters
         String: LPCWSTR
         Number: LPVOID
         Number: INT

See more info concerning these CRT functions on MSDN :
_itoa, _i64toa, _ui64toa, _itow, _i64tow, _ui64tow
strtol, wcstol, _strtol_l, _wcstol_l

The next piece of code converts a decimal integer to the given base

   Call SalStrSetBufferLength( sBuffer, 32 )
   ! Set nToBase to 2..36 (2 = binary, 8 = octal, 10 = decimal, 16 = hexadecimal)
   Call _itoa( nDecimalNumber, sBuffer, nToBase )
   ! sBuffer holds the converted decimal in the given base

Here the code to convert a base number to decimal

   Set nNumber = strtol( sBaseValue, NUMBER_Null, nBase )

Examples

   ! Next, decimal to hexadecimal
   Call _itoa( 125, sBuffer, 16 )
   ! sBuffer = "7d"
   ! Next, decimal to octal
   Call _itoa( 125, sBuffer, 8 )
   ! sBuffer = "175"
   ! Next, decimal to binary
   Call _itoa( 125, sBuffer, 2)
   ! sBuffer = "1111101"
   !
   ! Next, binary to decimal
   Set nNumber = strtol( "101, NUMBER_Null, 2 )
   ! nNumber = 5

Using these functions you are able to convert from one base to another.

The sample can be downloaded below, it uses wrapper PAL functions for the CRT functions and a Base2Base function.
(Separate TD5.x sample provided)

• WIKI_Number2Base_VisaVersa.zip
  
• WIKI_Number2Base_VisaVersa_TD5x.zip
  

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