On Error statement

On Error { GoTo line | Resume Next | GoTo 0 }

Sets BlueZone Basic’s error-handling method and if applicable specifies the line label of the error-handling routine.

The line parameter refers to a label. That label must be present in the code or an error is generated.

Review the use of the following properties in the examples below:

.Number: The error code value.
.Description: The string associated with the given error number.
.LineNumber: The line number in source of the error.

Example 1:

Sub Main
   On Error GoTo dude   ' Turn on error checking
   Dim x as object
   x.draw   ' Object not set
   jpe   ' Undefined function call
   print 1/0   ' Division by zero
   Err.Raise 6   ' Generate an "Overflow" error
   MsgBox "Back"
   MsgBox "Jack"
   Exit Sub
 
dude:
   On Error Resume Next   ' turn off error checking
   MsgBox "HELLO"
   Print Err.Number, Err.Description
   Resume Next
   MsgBox "Should not get here!"
   MsgBox "What?"
   On Error Goto 0   ' turn on error checking
End Sub

Example 2:

Sub mySub( myStr As String )
MsgBox myStr
End Sub

Sub Main
Dim vbCrlf As String
On Error Goto MyErr
vbCrlf = Chr(13) & Chr(10)

mySub myChk2Var
mySub 1,2
Exit Sub
MyErr:
MsgBox "Error on line: " & err.LineNumber & vbCrlf & "Number: "
& err.Number & vbCrlf & "Description: " & err.Description

End Sub

Errors can be raised with the syntax

Err.Raise x

The tables below show the corresponding descriptions for the defined values of x.

Table 1: Syntax error values
Value of `x`	Description
5	“Invalid procedure call”
6	“Overflow”
7	“Out of memory”
9	“Subscript out of range”
10	“Array is fixed or temporarily locked”
11	“Division by zero”
13	“Type mismatch”
14	“Out of string space”
16	“Expression too complex”
17	“Can't perform requested operation”
18	“User interrupt occurred”
20	“Resume without error”
28	“Out of stack space”
35	“Sub, Function, or Property not defined”
47	“Too many DLL application clients”
48	“Error in loading DLL”
49	“Bad DLL calling convention”
51	“Internal error”
52	“Bad file name or number”
53	“File not found”
54	“Bad file mode”
55	“File already open”
57	“Device I/O error”
58	“File already exists”
59	“Bad record length”
60	“Disk full”
62	“Input past end of file”
63	“Bad record number”
67	“Too many files”
68	“Device unavailable”
70	“Permission denied”
71	“Disk not ready”
74	“Can't rename with different drive”
75	“Path/File access error”
76	“Path not found”
91	“Object variable or With block variable not set”
92	“For loop not initialized”
93	“Invalid pattern string”
94	“Invalid use of Null”

Table 2: OLE Automation messages
Value of `x`	Description
429	“OLE Automation server cannot create object”
430	“Class doesn't support OLE Automation”
432	“File name or class name not found during OLE Automation operation”
438	“Object doesn't support this property or method”
440	“OLE Automation error”
443	“OLE Automation object does not have a default value”
445	“Object doesn't support this action”
446	“Object doesn't support named arguments”
447	“Object doesn't support current local setting”
448	“Named argument not found”
449	“Argument not optional”
450	“Wrong number of arguments”
451	“Object not a collection”

Table 3: Miscellaneous messages
Value of `x`	Description
444	“Method not applicable in this context”
452	“Invalid ordinal”
453	“Specified DLL function not found”
457	“Duplicate Key”
460	“Invalid Clipboard format”
461	“Specified format doesn't match format of data”
480	“Can't create AutoRedraw image”
481	“Invalid picture”
482	“Printer error”
483	“Printer driver does not supported specified property”
484	“Problem getting printer information from the system”

Table 4: Printer messages
Value of `x`	Description
485	“Invalid picture type”
520	“Can't empty Clipboard”
521	“Can't open Clipboard”