Chr Function

Returns a String containing the character associated with the specified character code.

Syntax

Chr(charcode)

Parameters

• charcode: Required. Long value that identifies a character. The valid range for charcode is 0-255. For values outside this range, an error occurs.

Return Value

Returns a String containing the single character corresponding to the specified character code. For charcode values 0-127, this corresponds to the ASCII character set. For values 128-255, this corresponds to the extended ASCII or ANSI character set based on the system's code page.

Remarks

The Chr function is the inverse of the Asc function. While Asc returns the numeric character code of a character, Chr returns the character for a given code.

Important Characteristics:

• Valid range: 0-255 (Error 5 "Invalid procedure call or argument" for values outside range)
• Chr(0) returns a null character (vbNullChar)
• Chr(13) returns carriage return (vbCr)
• Chr(10) returns line feed (vbLf)
• Chr(9) returns tab character (vbTab)
• Values 0-31 are non-printable control characters
• Values 32-126 are standard printable ASCII characters
• Values 127-255 depend on the system code page (often Windows-1252 in VB6)

Common Character Codes

Examples

Basic Usage

' Get character from code
Dim ch As String
ch = Chr(65)  ' Returns "A"
ch = Chr(97)  ' Returns "a"
ch = Chr(48)  ' Returns "0"

' Special characters
ch = Chr(32)  ' Returns space " "
ch = Chr(13)  ' Returns carriage return
ch = Chr(10)  ' Returns line feed

Line Breaks and Special Characters

' Create multi-line string
Dim msg As String
msg = "Line 1" & Chr(13) & Chr(10) & "Line 2"
' Or use the constant
msg = "Line 1" & vbCrLf & "Line 2"

' Tab-separated values
Dim data As String
data = "Name" & Chr(9) & "Age" & Chr(9) & "City"

Building Strings from Codes

' Build alphabet
Dim i As Integer
Dim alphabet As String
For i = 65 To 90
alphabet = alphabet & Chr(i)
Next i
' alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

Common Patterns

Generating Character Sequences

Function GetAlphabet(uppercase As Boolean) As String
Dim result As String
Dim i As Integer
Dim startCode As Integer

If uppercase Then
startCode = 65  ' 'A'
Else
startCode = 97  ' 'a'
End If

For i = startCode To startCode + 25
result = result & Chr(i)
Next i

GetAlphabet = result
End Function

Quote Handling

Function QuoteString(text As String) As String
QuoteString = Chr(34) & text & Chr(34)
End Function

' Usage: result = QuoteString("Hello")  ' Returns: "Hello"

CSV Generation

Function CreateCSVRow(ParamArray fields() As Variant) As String
Dim result As String
Dim i As Integer
Dim field As String

For i = LBound(fields) To UBound(fields)
field = CStr(fields(i))

' Quote fields containing commas or quotes
If InStr(field, ",") > 0 Or InStr(field, Chr(34)) > 0 Then
field = Chr(34) & Replace(field, Chr(34), Chr(34) & Chr(34)) & Chr(34)
End If

If i > LBound(fields) Then result = result & ","
result = result & field
Next i

CreateCSVRow = result
End Function

Control Character Removal

Function RemoveControlChars(text As String) As String
Dim result As String
Dim i As Integer
Dim ch As String
Dim code As Integer

For i = 1 To Len(text)
ch = Mid(text, i, 1)
code = Asc(ch)

' Keep only printable characters (32-126) and common whitespace
If code >= 32 Or code = 9 Or code = 10 Or code = 13 Then
result = result & ch
End If
Next i

RemoveControlChars = result
End Function

String Encoding/Decoding

Function EncodeString(text As String) As String
Dim result As String
Dim i As Integer

For i = 1 To Len(text)
If i > 1 Then result = result & ","
result = result & CStr(Asc(Mid(text, i, 1)))
Next i

EncodeString = result
End Function

Function DecodeString(encoded As String) As String
Dim result As String
Dim codes() As String
Dim i As Integer

codes = Split(encoded, ",")
For i = LBound(codes) To UBound(codes)
result = result & Chr(CLng(codes(i)))
Next i

DecodeString = result
End Function

Random Character Generation

Function GeneratePassword(length As Integer) As String
Dim result As String
Dim i As Integer
Dim charType As Integer

Randomize

For i = 1 To length
charType = Int(Rnd * 3)  ' 0=uppercase, 1=lowercase, 2=digit

Select Case charType
Case 0  ' Uppercase A-Z
result = result & Chr(65 + Int(Rnd * 26))
Case 1  ' Lowercase a-z
result = result & Chr(97 + Int(Rnd * 26))
Case 2  ' Digit 0-9
result = result & Chr(48 + Int(Rnd * 10))
End Select
Next i

GeneratePassword = result
End Function

Box Drawing Characters

Function DrawBox(width As Integer, height As Integer) As String
Dim result As String
Dim i As Integer

' Top border (using extended ASCII box characters)
result = Chr(218)  ' Top-left corner
For i = 1 To width - 2
result = result & Chr(196)  ' Horizontal line
Next i
result = result & Chr(191) & vbCrLf  ' Top-right corner

' Middle rows
For i = 1 To height - 2
result = result & Chr(179)  ' Vertical line
result = result & Space(width - 2)
result = result & Chr(179) & vbCrLf  ' Vertical line
Next i

' Bottom border
result = result & Chr(192)  ' Bottom-left corner
For i = 1 To width - 2
result = result & Chr(196)  ' Horizontal line
Next i
result = result & Chr(217)  ' Bottom-right corner

DrawBox = result
End Function

Character Case Conversion

Function ToggleCase(text As String) As String
Dim result As String
Dim i As Integer
Dim ch As String
Dim code As Integer

For i = 1 To Len(text)
ch = Mid(text, i, 1)
code = Asc(ch)

If code >= 65 And code <= 90 Then
' Uppercase -> lowercase
result = result & Chr(code + 32)
ElseIf code >= 97 And code <= 122 Then
' Lowercase -> uppercase
result = result & Chr(code - 32)
Else
result = result & ch
End If
Next i

ToggleCase = result
End Function

Advanced Usage

Binary Data Handling

Function BytesToString(bytes() As Byte) As String
Dim result As String
Dim i As Long

For i = LBound(bytes) To UBound(bytes)
result = result & Chr(bytes(i))
Next i

BytesToString = result
End Function

Function StringToBytes(text As String) As Byte()
Dim bytes() As Byte
Dim i As Long

ReDim bytes(1 To Len(text))

For i = 1 To Len(text)
bytes(i) = Asc(Mid(text, i, 1))
Next i

StringToBytes = bytes
End Function

Unicode Support (ChrW variant)

' Note: VB6 has ChrW for Unicode characters
Function GetUnicodeChar(code As Long) As String
' For codes 0-255, Chr and ChrW are equivalent
If code <= 255 Then
GetUnicodeChar = Chr(code)
Else
' For codes > 255, use ChrW (not covered by Chr function)
GetUnicodeChar = ChrW(code)
End If
End Function

Escape Sequence Processing

Function ProcessEscapeSequences(text As String) As String
Dim result As String
result = text

' Replace common escape sequences
result = Replace(result, "\n", Chr(10))   ' Line feed
result = Replace(result, "\r", Chr(13))   ' Carriage return
result = Replace(result, "\t", Chr(9))    ' Tab
result = Replace(result, "\\", Chr(92))   ' Backslash
result = Replace(result, "\""", Chr(34))  ' Double quote

ProcessEscapeSequences = result
End Function

Error Handling

Function SafeChr(charcode As Long) As String
On Error GoTo ErrorHandler

If charcode < 0 Or charcode > 255 Then
Err.Raise 5, , "Invalid character code: " & charcode
End If

SafeChr = Chr(charcode)
Exit Function

ErrorHandler:
MsgBox "Error in Chr: " & Err.Description
SafeChr = ""
End Function

Common Errors

• Error 5 (Invalid procedure call or argument): Character code is outside the range 0-255
• Error 13 (Type mismatch): Argument is not numeric

Performance Considerations

• Chr is a fast function with minimal overhead
• For building long strings with many Chr calls, consider using a StringBuilder pattern
• Avoid repeated Chr calls for the same character code (use a constant instead)
• For Unicode support beyond 255, use ChrW or ChrB functions

VB6 String Constants vs Chr

VB6 provides built-in constants for common characters:

' Prefer constants over Chr for readability
vbCr        ' Chr(13) - Carriage return
vbLf        ' Chr(10) - Line feed
vbCrLf      ' Chr(13) & Chr(10) - Carriage return + line feed
vbTab       ' Chr(9) - Tab
vbNullChar  ' Chr(0) - Null character
vbNullString ' Empty string ""

Limitations

• Limited to character codes 0-255 (single-byte characters)
• For Unicode beyond 255, use ChrW instead
• Character interpretation depends on system code page
• Control characters (0-31) may not display in UI controls
• Extended ASCII (128-255) may vary across systems

Related Functions

• Asc: Returns the character code of the first character in a string (inverse of Chr)
• ChrW: Returns Unicode character for character codes 0-65535
• ChrB: Returns a byte containing the character code
• AscW: Returns the Unicode character code
• AscB: Returns the byte value