LoadResData Function

Returns the data stored in a resource (.res) file.

Syntax

LoadResData(index, format)

Parameters

• index (Required): Integer or String identifying the resource
• Can be a numeric ID or string name
• Must match the ID/name used when the resource was compiled
• format (Required): Integer specifying the format of the resource data
• Custom user-defined format number (1-32767)
• Cannot use predefined formats (use LoadResPicture/LoadResString instead)

Return Value

Returns a Byte array (Variant containing Byte array): - Contains the raw binary data from the resource file - Array is zero-based - Returns Empty if resource not found (in some VB versions) - May raise error 32813 if resource not found - Data is returned exactly as stored in .res file

Remarks

The LoadResData function loads custom binary data from resources:

• Loads custom data from compiled resource (.res) files
• Resource file must be linked to project at compile time
• Returns data as Byte array (Variant/Byte())
• Used for custom binary resources (not bitmaps/icons/strings)
• For images, use LoadResPicture instead
• For strings, use LoadResString instead
• Resource files created with Resource Editor or RC.EXE
• Index can be numeric ID or string name
• Format must be custom type (not 1=Cursor, 2=Bitmap, 3=Icon, etc.)
• Useful for embedding files (sounds, data, etc.)
• Data embedded in compiled EXE (no external files needed)
• More secure than external files (can't be easily modified)
• Faster access than loading from disk
• Resource file added via Project > Add File or in .vbp
• Only one resource file per project
• Changes to .res file require recompile
• Error 32813: "Resource not found" if ID/format don't match
• Error 48: "Error loading from file" if resource file corrupt

Typical Uses

1. Load Binary Data

Dim data() As Byte
data = LoadResData(101, 256) ' Custom format 256

1. Load Sound File

Dim wavData() As Byte
wavData = LoadResData("STARTUP_SOUND", 257)

1. Load Configuration Data

Dim configData() As Byte
configData = LoadResData("CONFIG", 300)

1. Load Binary Template

Dim template() As Byte
template = LoadResData(1001, 400)

1. Load Custom File Type

Dim xmlData() As Byte
xmlData = LoadResData("SCHEMA", 500)

1. Load Multiple Resources

For i = 1 To 5
data = LoadResData(i, 256)
ProcessData data
Next i

1. Load Named Resource

Dim helpData() As Byte
helpData = LoadResData("HELP_FILE", 600)

1. Conditional Loading

If useCustomTheme Then
themeData = LoadResData("DARK_THEME", 700)
End If

Basic Examples

Example 1: Loading and Using Binary Data

' Load binary data from resource
Dim resourceData() As Byte
resourceData = LoadResData(101, 256)

' Use the data
Dim fileNum As Integer
fileNum = FreeFile
Open "C:\output.dat" For Binary As #fileNum
Put #fileNum, , resourceData
Close #fileNum

Example 2: Loading Sound Data

' Load WAV file from resources
Dim wavData() As Byte
wavData = LoadResData("BEEP", 257)

' Play using Windows API
Call sndPlaySound(wavData(0), SND_ASYNC Or SND_MEMORY)

Example 3: Error Handling

On Error Resume Next
Dim data() As Byte
data = LoadResData(999, 256)
If Err.Number = 32813 Then
MsgBox "Resource not found!", vbCritical
Err.Clear
ElseIf Err.Number <> 0 Then
MsgBox "Error loading resource: " & Err.Description, vbCritical
Err.Clear
End If

Example 4: Converting to String

' Load text data stored as binary
Dim textData() As Byte
textData = LoadResData("README", 300)

' Convert byte array to string
Dim content As String
content = StrConv(textData, vbUnicode)
MsgBox content

Common Patterns

Pattern 1: SafeLoadResData

Function SafeLoadResData(ByVal resID As Variant, _
ByVal resFormat As Integer, _
ByRef outData() As Byte) As Boolean
On Error Resume Next
outData = LoadResData(resID, resFormat)
SafeLoadResData = (Err.Number = 0)
Err.Clear
End Function

Pattern 2: LoadResDataToFile

Sub LoadResDataToFile(ByVal resID As Variant, _
ByVal resFormat As Integer, _
ByVal filename As String)
Dim data() As Byte
Dim fileNum As Integer

data = LoadResData(resID, resFormat)

fileNum = FreeFile
Open filename For Binary As #fileNum
Put #fileNum, , data
Close #fileNum
End Sub

Pattern 3: GetResDataSize

Function GetResDataSize(ByVal resID As Variant, _
ByVal resFormat As Integer) As Long
On Error Resume Next
Dim data() As Byte
data = LoadResData(resID, resFormat)

If Err.Number = 0 Then
GetResDataSize = UBound(data) + 1
Else
GetResDataSize = 0
End If
End Function

Pattern 4: LoadResDataAsString

Function LoadResDataAsString(ByVal resID As Variant, _
ByVal resFormat As Integer) As String
Dim data() As Byte
data = LoadResData(resID, resFormat)
LoadResDataAsString = StrConv(data, vbUnicode)
End Function

Pattern 5: ResDataExists

Function ResDataExists(ByVal resID As Variant, _
ByVal resFormat As Integer) As Boolean
On Error Resume Next
Dim data() As Byte
data = LoadResData(resID, resFormat)
ResDataExists = (Err.Number = 0)
Err.Clear
End Function

Pattern 6: LoadMultipleResources

Function LoadMultipleResources(startID As Integer, _
endID As Integer, _
resFormat As Integer) As Collection
Dim col As New Collection
Dim i As Integer
Dim data() As Byte

On Error Resume Next
For i = startID To endID
data = LoadResData(i, resFormat)
If Err.Number = 0 Then
col.Add data
End If
Err.Clear
Next i

Set LoadMultipleResources = col
End Function

Pattern 7: CompareResData

Function CompareResData(ByVal resID1 As Variant, _
ByVal resID2 As Variant, _
ByVal resFormat As Integer) As Boolean
Dim data1() As Byte, data2() As Byte
Dim i As Long

data1 = LoadResData(resID1, resFormat)
data2 = LoadResData(resID2, resFormat)

If UBound(data1) <> UBound(data2) Then
CompareResData = False
Exit Function
End If

For i = 0 To UBound(data1)
If data1(i) <> data2(i) Then
CompareResData = False
Exit Function
End If
Next i

CompareResData = True
End Function

Pattern 8: CopyResDataToArray

Sub CopyResDataToArray(ByVal resID As Variant, _
ByVal resFormat As Integer, _
ByRef targetArray() As Byte)
Dim source() As Byte
Dim i As Long

source = LoadResData(resID, resFormat)
ReDim targetArray(LBound(source) To UBound(source))

For i = LBound(source) To UBound(source)
targetArray(i) = source(i)
Next i
End Sub

Pattern 9: LoadResDataWithFallback

Function LoadResDataWithFallback(ByVal primaryID As Variant, _
ByVal fallbackID As Variant, _
ByVal resFormat As Integer) As Byte()
On Error Resume Next

LoadResDataWithFallback = LoadResData(primaryID, resFormat)
If Err.Number <> 0 Then
Err.Clear
LoadResDataWithFallback = LoadResData(fallbackID, resFormat)
End If
End Function

Pattern 10: CachedResDataLoader

Dim resCache As New Collection

Function LoadResDataCached(ByVal resID As Variant, _
ByVal resFormat As Integer) As Byte()
Dim key As String
On Error Resume Next

key = CStr(resID) & "_" & CStr(resFormat)

' Try cache first
LoadResDataCached = resCache(key)
If Err.Number <> 0 Then
' Not in cache, load and cache it
Err.Clear
LoadResDataCached = LoadResData(resID, resFormat)
resCache.Add LoadResDataCached, key
End If
End Function

Advanced Examples

Example 1: Resource Manager Class

' Class: ResourceManager
Private m_cache As Collection

Private Sub Class_Initialize()
Set m_cache = New Collection
End Sub

Public Function LoadData(ByVal resID As Variant, _
ByVal resFormat As Integer) As Byte()
Dim key As String
On Error Resume Next

key = CStr(resID) & "_" & CStr(resFormat)
LoadData = m_cache(key)

If Err.Number <> 0 Then
Err.Clear
LoadData = LoadResData(resID, resFormat)
If Err.Number = 0 Then
m_cache.Add LoadData, key
Else
Err.Raise vbObjectError + 1000, "ResourceManager", _
"Failed to load resource"
End If
End If
End Function

Public Function GetAsString(ByVal resID As Variant, _
ByVal resFormat As Integer) As String
Dim data() As Byte
data = LoadData(resID, resFormat)
GetAsString = StrConv(data, vbUnicode)
End Function

Public Sub SaveToFile(ByVal resID As Variant, _
ByVal resFormat As Integer, _
ByVal filename As String)
Dim data() As Byte
Dim fileNum As Integer

data = LoadData(resID, resFormat)
fileNum = FreeFile
Open filename For Binary As #fileNum
Put #fileNum, , data
Close #fileNum
End Sub

Public Sub ClearCache()
Set m_cache = New Collection
End Sub

Private Sub Class_Terminate()
Set m_cache = Nothing
End Sub

Example 2: Sound Player with Resources

' Module with API declarations
Private Declare Function sndPlaySound Lib "winmm.dll" Alias "sndPlaySoundA" ( _
lpszSoundName As Any, ByVal uFlags As Long) As Long

Private Const SND_ASYNC = &H1
Private Const SND_MEMORY = &H4

' Sound resource IDs
Private Const RES_SOUND_BEEP = 101
Private Const RES_SOUND_CLICK = 102
Private Const RES_SOUND_ERROR = 103
Private Const RES_FORMAT_WAVE = 257

Public Sub PlayResourceSound(ByVal soundID As Integer)
Dim soundData() As Byte
On Error Resume Next

soundData = LoadResData(soundID, RES_FORMAT_WAVE)
If Err.Number = 0 Then
Call sndPlaySound(soundData(0), SND_ASYNC Or SND_MEMORY)
Else
Debug.Print "Sound not found: " & soundID
End If
End Sub

Public Sub PlayBeep()
PlayResourceSound RES_SOUND_BEEP
End Sub

Public Sub PlayClick()
PlayResourceSound RES_SOUND_CLICK
End Sub

Public Sub PlayError()
PlayResourceSound RES_SOUND_ERROR
End Sub

Example 3: Configuration Manager

' Class: ConfigManager
Private m_config As String

Public Sub LoadConfig()
Dim configData() As Byte
On Error Resume Next

' Try to load from resource
configData = LoadResData("CONFIG", 300)
If Err.Number = 0 Then
m_config = StrConv(configData, vbUnicode)
Else
' Use default config
m_config = GetDefaultConfig()
End If
Err.Clear
End Sub

Public Function GetSetting(ByVal key As String) As String
Dim lines() As String
Dim i As Long
Dim pos As Long

lines = Split(m_config, vbCrLf)
For i = 0 To UBound(lines)
If Left(lines(i), Len(key) + 1) = key & "=" Then
GetSetting = Mid(lines(i), Len(key) + 2)
Exit Function
End If
Next i
End Function

Private Function GetDefaultConfig() As String
GetDefaultConfig = "Version=1.0" & vbCrLf & _
"Language=English" & vbCrLf & _
"Theme=Default"
End Function

Example 4: Template Engine

' Class: TemplateEngine
Private Const RES_FORMAT_TEMPLATE = 400

Public Function ProcessTemplate(ByVal templateID As Variant, _
ParamArray values()) As String
Dim template As String
Dim data() As Byte
Dim i As Long
Dim result As String

' Load template from resources
data = LoadResData(templateID, RES_FORMAT_TEMPLATE)
template = StrConv(data, vbUnicode)

result = template

' Replace placeholders with values
For i = LBound(values) To UBound(values)
result = Replace(result, "{" & i & "}", CStr(values(i)))
Next i

ProcessTemplate = result
End Function

Public Function LoadTemplate(ByVal templateID As Variant) As String
Dim data() As Byte
data = LoadResData(templateID, RES_FORMAT_TEMPLATE)
LoadTemplate = StrConv(data, vbUnicode)
End Function

Public Function HasTemplate(ByVal templateID As Variant) As Boolean
On Error Resume Next
Dim data() As Byte
data = LoadResData(templateID, RES_FORMAT_TEMPLATE)
HasTemplate = (Err.Number = 0)
Err.Clear
End Function

Error Handling

' Error 32813: Resource not found
On Error Resume Next
data = LoadResData(999, 256)
If Err.Number = 32813 Then
MsgBox "Resource ID 999 not found!"
End If

' Error 48: Error loading from file
data = LoadResData(101, 256)
If Err.Number = 48 Then
MsgBox "Resource file is corrupt or missing!"
End If

' Safe loading with error handling
Function TryLoadResData(ByVal resID As Variant, _
ByVal resFormat As Integer, _
ByRef outData() As Byte) As Boolean
On Error Resume Next
outData = LoadResData(resID, resFormat)
TryLoadResData = (Err.Number = 0)
If Err.Number <> 0 Then
Debug.Print "Error loading resource: " & Err.Description
End If
Err.Clear
End Function

Performance Considerations

• Fast Access: Resources are embedded in EXE (very fast loading)
• Memory Overhead: Data loaded into memory when accessed
• No Caching: Each call loads fresh copy (implement caching if needed)
• Compile Time: Large resources increase EXE size and compile time
• One Resource File: Only one .res file per project (combine all resources)
• Array Copy: Returns copy of data (not reference)

Best Practices

1. Always handle errors - resource might not exist
2. Use constants for resource IDs and formats
3. Cache frequently used data to avoid repeated loading
4. Use meaningful names for string-based resource IDs
5. Document resource IDs in code or separate file
6. Keep resources organized by format number
7. Test resource loading during development
8. Validate data size after loading if needed
9. Consider memory usage for large resources
10. Use appropriate formats - LoadResPicture for images, LoadResString for text

Comparison with Related Functions

LoadResData vs LoadResPicture vs LoadResString

' LoadResData - custom binary data
Dim binData() As Byte
binData = LoadResData(101, 256)

' LoadResPicture - images
Picture1.Picture = LoadResPicture(101, vbResBitmap)

' LoadResString - strings
Dim msg As String
msg = LoadResString(101)

When to use each: - LoadResData: Custom binary files, sound files, configuration data - LoadResPicture: Images (bitmaps, icons, cursors) - LoadResString: Localized text strings

Platform Notes

• Available in VB6 (not in early VB versions)
• Requires resource file (.res) linked to project
• Resource file created with Resource Editor or RC.EXE
• Only one resource file per project
• Resources embedded in compiled EXE/DLL
• Returns Variant containing Byte array
• Array is always zero-based (0 to n-1)
• Custom formats: 1-32767 (avoid predefined formats)
• Maximum resource size limited by available memory

Limitations

• One resource file: Only one .res file per project
• Compile time: Must recompile to update resources
• No modification: Cannot modify resources at runtime
• Limited tools: VB6 Resource Editor is basic
• Format restrictions: Cannot use predefined formats (1-16)
• No compression: Resources stored uncompressed in EXE
• No encryption: Resources easily extractable from EXE
• Memory copy: Always returns copy of data (not reference)
• Error messages: Limited error information
• No streaming: Entire resource loaded into memory

Related Functions

• LoadResPicture: Load picture from resource file
• LoadResString: Load string from resource file
• LoadPicture: Load picture from external file
• StrConv: Convert byte array to string
• FreeFile: Get file number for saving resource data