GAMBAS BOOK 3.19.1

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Gambas functions

Chapters

  1. Gambas
  2. Gambas installation
  3. The language of Gambas
  4. Development Environment (IDE)
  5. Gambas architecture
  6. Streams
  7. Data types
  8. Operators
  9. Gambas functions
  10. Control structures
  11. Program development
  12. Forms
  13. Menus
  14. Keyboard and mouse
  15. Desktop
  16. Control elements 1
  17. Control elements 2
  18. Control elements 3
  19. Control elements 4
  20. Selected classes
  21. Process management
  22. Databases
  23. Multimedia
  24. Communication and Network
  25. 2D-Graphics
  26. 3D-Graphics
  27. XML
  28. Compression|Encryption
  29. Scientific Libraries
  30. Module and classes
  31. This and that ...
08.10.2022
k9:k9.10:start

Table of Contents

9.10 Conversion functions

In many programs, conversions between different data types are necessary if, for example, values from a TextBox are to be processed as numbers or as dates according to the type. For all conversion functions, note the data type of the arguments and the data type of the function value as well as the notes on localization.

9.10.1 Table of selected conversion functions

FunctionDescription
CBool(Expr) AS BooleanConverts an expression to a true or false value. An expression is guaranteed to be incorrect if a true value is wrong or a number is 0 or the string length is 0 or a NULL date exists or a zero object.
CByte(Expr AS Variant) AS ByteConverts an expression into a byte. The expression is first converted to an integer value. If the integer value exceeds the byte range[0… 255] then it is transformed (modulo 256) into this range.
CDate(Expr AS Variant) AS DateConverts an expression (number of data type integer or float) into a date/time string. CDate does not use the current localization!
CFloat(expr AS Variant) AS Float↓
CFlt(Expr AS Variant) AS FloatConverts an expression to a floating point number. Careful! This function does not use the selected localization. A dot must be set as a decimal separator!
CInt(Expr AS Variant) AS Integer↓
CInteger(Expr AS Variant) AS IntegerConverts an expression into a number of the data type integer.
CLong(Expr AS Variant) AS LongConverts an expression to a number of the data type Long. An overrange is not detected.
CShort (Expr AS Variant) AS ShortConverts an expression into a number of the data type Short. The expression is first converted to an integer value. If the integer value exceeds the short range[-32.768… 32.767], then it is transformed into this range. The least significant 16 bits are extracted from Expr and interpreted as an integer in the sense of the two's complement.
CSingle(Expr AS Variant) AS SingleConverts an expression into a number of the data type Single. This function does not use the set localization!
CStr(Expr AS Variant) AS String↓
CString(Expr AS Variant) AS StringConverts an expression into a string. This function does not use the set localization!
CVar(expr) AS Variant↓
CVariant(Expr) AS VariantConverts an expression to a variant. This is useful if the result of a function depends on the data type of the arguments.
Str$(expr) AS String↓
Str(Expr) AS StringConverts a number or date into a string. This function observes the localization settings!
DConv$(string AS string) AS String↓
DConv(string AS string) AS StringConverts a string from the system character set to UTF-8, the desktop character set.
SConv$(string AS string)↓
SConv(string AS string)Converts a string from the desktop character set (which should be UTF-8) to the system character set.
Val(string)Converts a string into a number or date. This function takes into account the selected localization!

Table 9.10.1.1: Overview of the conversion functions

The conversion algorithm for the Val () function is the following:

  • If the string can be interpreted as date and time (with a date or time separator corresponding to the localization), the date or time is returned.
  • If the string is interpreted as a floating point number, the number is returned.
  • If the string can be interpreted as a 64-bit number, then this number of the data type Long is returned. Otherwise, if the string can be interpreted as an integer, this integer is returned.
  • If String = “True” or String = “False”, the matching truth values “True” or “False” are returned.
  • In all other cases NULL is returned.

9.10.2 Conversion functions for character sets

ConvertedString = Conv$(string AS string, source character set AS string, target character set AS string)
ConvertedString = Conv(string AS string, source character set AS string, target character set AS string)

Converts a string from one character set to another. A character set is represented by a string such as ASCII, ISO-8859-1, or UTF-8.

  • The Gambas interpreter uses the UTF-8 character set internally.
  • The character set used by the system is returned in the' System. Charset' property.
  • In the future probably all Linux systems will be based on UTF-8.
  • The character set used by the graphical user interface is provided by Desktop. charset. This should be UTF-8.

9.10.3 Examples

Dim sNumber As Single

Print CBool(0), CBool(1), CBool("Gambas"), CBool(""), CBool(Zero), CBool(Date(2000, 2, 29))

Print CByte("23"), CByte("257"), CByte(True)

Print "CDate(2488913) = "; CDate(2488913)
Print "UnixTimeStamp  = "; DateDiff(CDate("1/1/1970"), Now, gb.Second)
Try CDate("12.2. 2014 12:45:00")
If Error.Code = 6 Then Print "The expression ''; "12.2. 2014 12:45:00"; "' cannot be converted!"
Print "Date: ", Format(CDate(Val("1.9.2012")), "d. mmmm yyyy")
Print "Days since 1.1. 1970 = "; DateDiff(CDate("1/1/1970"), Now, gb.Day) ' 16224

Print CFloat("+3.1416"), CFloat(Now())

Print CInt("17"), CInt(True), CInt(Pi(1 / 7)), CInt(3.8), CInt(-7.998), CInt(-7.1), CInt(Now)

Print "CLong(5 ^ (2 ^ 2)) = "; CLong(5 ^ (2 ^ 2))
Print "CLong(2^62) = "; CLong(2 ^ 62)

Print CShort(20 < 6), CShort(False), CShort(True), CShort(DateDiff(CDate("1/1/1970"), Now, gb.Day))

Try sNumber = CSingle(DateDiff(CDate("1/1/1970"), Now(), gb.Millisecond))
If Error Then Print "OVERVIEW"
Print CSingle(Pi), CFloat(Pi), CSingle(Exp(11)), CSingle("+355.11")

Print CStr(-99), CStr(Pi(Pi())), CStr(355 / 113), CStr(Now)

Print "Object.Type(CVariant([2, 3, 5])) = "; Object.Type(CVariant([2, 3, 5]))
Print "Object.Type(CVariant([\"2\",\"3\",\"5\"])) = "; Object.Type(CVariant(["2", "3", "5"]))
Print "Object.Type([CVariant(\"a\"),\"b\",\"c\"]) = "; Object.Type([CVariant("a"), "b", "c"])

Print "Val(\"True\") = "; Val("True"), "Val(\"False\") = "; Val("False")
Print Format(Val("12.11.2013"), "d. mmmm yyyy")
Print "Val(\"123,456\") = "; Val("123,456"); " (Number with comma as decimal separator for DE.de)"
Print "Val(\"123.456\") = "; Val("123.456"); " (Point is interpreted as a thousands separator!)"
If Val("123.66") = Zero Then Print "Val(\"123.66\") = ZERO"; " (String cannot be interpreted as a number.)"

Print Conv("Trouble on Oedipus Street", System.Charset, "ISO 8859-15")
Print "Desktop-Characterset = "; Desktop.Charset
Print "System-Character set  = "; System.Charset
False   True    True    False   False   True
23      1       255
CDate(2488913) = 30.05.2014 23:00:00
UnixTimeStamp  = 1401992840
The expression' 12.2.2014 12:45:00' cannot be converted!
Date:  1. September 2012
Days since 1.1. 1970 = 16226
3,1416  2488918,81065353
17      -1      0       3       -7      -7      2488918
CLong(5 ^ (2 ^ 2)) = 625
CLong(2^62) = 4611686018427387904
0       0       -1      16226
Overflow
3,1415927       3,14159265358979        59874,140625    355,1099854
-99     9.86960440108936        3.14159292035398        06/05/2014 18:27:20.466
Object.Type(CVariant([2, 3, 5]))     = Integer[]
Object.Type(CVariant(["2","3","5"])) = String[]
Object.Type([CVariant("a"),"b","c"]) = Variant[]
Val("True") = True      Val("False") = False
12. November 2013
Val("123,456") = 123,456 (Number with comma as decimal separator for DE.de)
Val("123.456") = 123456 (Point is interpreted as a thousands separator!)
Val("123.66") = ZERO (String cannot be interpreted as a number.)
�rger in der �dipus-Stra�e
Desktop-Character set = UTF-8
System-Character set  = UTF-8
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k9/k9.10/start.txt · Last modified: 11.02.2022 (external edit)

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