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