Type

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4D v18

Type


Type ( fieldVar ) -> Function result

Parameter	Type	Description
fieldVar	Field, Variable	field or variable to be tested
Function result	Longint	Data type number

Description

The Type command returns a numeric value that indicates the type of field or variable you have passed in the fieldVar parameter.

4D provides the following predefined constants found in the Field and Variable Types theme:

Constant	Type	Value
Array 2D	Longint	13
Blob array	Longint	31
Boolean array	Longint	22
Date array	Longint	17
Integer array	Longint	15
Is alpha field	Longint	0
Is BLOB	Longint	30
Is Boolean	Longint	6
Is collection	Longint	42
Is date	Longint	4
Is integer	Longint	8
Is integer 64 bits	Longint	25
Is longint	Longint	9
Is null	Longint	255
Is object	Longint	38
Is picture	Longint	3
Is pointer	Longint	23
Is real	Longint	1
Is string var	Longint	24
Is subtable	Longint	7
Is text	Longint	2
Is time	Longint	11
Is undefined	Longint	5
Is variant	Longint	12
LongInt array	Longint	16
Object array	Longint	39
Picture array	Longint	19
Pointer array	Longint	20
Real array	Longint	14
String array	Longint	21
Text array	Longint	18
Time array	Longint	32

You can apply the Type function to fields, interprocess variables, process variables, local variables, and dereferenced pointers for these types of objects. You can apply Type to the parameters ($1, $2 ... ${...}) of a project method or to the result of a function ($0).

Notes:

You can not apply the Type function to scalar expressions such as object properties (emp.name) or collection elements (myColl[5]). To do this, you must use the Value type command.
Calling Type on a method parameter ($0, $1...) declared as C_VARIANT does not return Is variant but the actual data type (same as calling Value type).

Example 1

The following project method empties some or all of the fields for the current record of the table whose a pointer is passed as parameter. It does this without deleting or changing the current record:

  ` EMPTY RECORD Project Method

  ` EMPTY RECORD ( Pointer {; Long } )

  ` EMPTY RECORD ( -> [Table] { ; Type Flags } )

 

 C_POINTER($1)

 C_LONGINT($2;$vlTypeFlags)

 

 If(Count parameters>=2)

    $vlTypeFlags:=$2

 Else

    $vlTypeFlags:=0xFFFFFFFF

 End if

 For($vlField;1;Get last field number($1))

    $vpField:=Field(Table($1);$vlField)

    $vlFieldType:=Type($vpField->)

    If($vlTypeFlags ??$vlFieldType )

       Case of

          :(($vlFieldType=Is alpha field)|($vlFieldType=Is text))

             $vpField->:=""

          :(($vlFieldType=Is real)|($vlFieldType=Is integer)|($vlFieldType=Is longint))

             $vpField->:=0

          :($vlFieldType=Is date)

             $vpField->:=!00/00/00!

          :($vlFieldType=Is time)

             $vpField->:=?00:00:00?

          :($vlFieldType=Is Boolean)

             $vpField->:=False

          :($vlFieldType=Is picture)

             C_PICTURE($vgEmptyPicture)

             $vpField->:=$vgEmptyPicture

          :($vlFieldType=Is subtable)

             Repeat

                ALL SUBRECORDS($vpField->)

                DELETE SUBRECORD($vpField->)

             Until(Records in subselection($vpField->)=0)

          :($vlFieldType=Is BLOB)

             SET BLOB SIZE($vpField->;0)

       End case

    End if

 End for

After this project method is implemented in your database, you can write:

  ` Empty the whole current record of the table [Things To Do]

 EMPTY RECORD(->[Things To Do])

 

  ` Empty Text, BLOB and Picture fields for the current record of the table [Things To Do]

 EMPTY RECORD(->[Things To Do];0?+Is text?+Is BLOB?+Is picture)

 

  ` Empty the whole current record of the table [Things To Do] except Alphanumeric fields

 EMPTY RECORD(->[Things To Do];-1?-Is alpha field)

Example 2

In certain cases, for example when writing generic code, you may need to find out whether an array is a standard independent array or the “row” of a 2D array. In this case, you can use the following code:

 ptrmyArr:=->myArr{6} ` Is myArr{6} the row of a 2D array?

 RESOLVE POINTER(ptrmyArr;varName;tableNum;fieldNum)

 If(varName#"")

    $ptr:=Get pointer(varName)

    $thetype:=Type($ptr->)

  ` If myArr{6} is the row of a 2D array, $thetype equals 13

 End if

Example 3

See example for the APPEND DATA TO PASTEBOARD command.