Left Function

Returns a String containing a specified number of characters from the left side of a string.

Syntax

Left(string, length)

Parameters

string (Required): String expression from which leftmost characters are returned
If string contains Null, Null is returned
length (Required): Long indicating how many characters to return
If 0, empty string ("") is returned
If greater than or equal to number of characters in string, entire string is returned
Must be non-negative (negative values cause error)

Return Value

Returns a String (or Variant containing String): - Contains the specified number of characters from the left side of the string - Returns empty string if length is 0 - Returns entire string if length >= Len(string) - Returns Null if string argument is Null - Always returns String type (Left$ variant returns String, not Variant)

Remarks

The Left function extracts characters from the beginning of a string: - Returns leftmost characters up to specified length - Complements Right function (which returns rightmost characters) - Works with Mid function for complete substring extraction - Zero-based extraction: Left("ABC", 2) returns "AB" - Safe with lengths exceeding string length (returns full string) - Null propagates through the function - Negative length raises Error 5 (Invalid procedure call or argument) - Common for extracting prefixes, file names, codes, etc. - More efficient than Mid(string, 1, length) for left extraction - Left$ variant returns String type (not Variant) for slight performance gain - Cannot extract from right side (use Right for that) - Cannot skip characters (use Mid for that) - Does not modify original string (strings are immutable)

Typical Uses

Extract Prefix: Get first N characters of string
Parse Codes: Extract code prefixes from identifiers
Truncate Text: Limit string length for display
File Extensions: Extract drive letter or path prefix
Validation: Check string starts with specific pattern
Data Parsing: Extract fixed-width field data
Formatting: Create abbreviations or short forms
Pattern Matching: Compare string prefixes

Basic Usage Examples

' Example 1: Basic left extraction
Dim text As String
text = "Hello World"
Debug.Print Left(text, 5)            ' "Hello"
Debug.Print Left(text, 3)            ' "Hel"
Debug.Print Left(text, 1)            ' "H"
' Example 2: Length exceeds string length
Debug.Print Left("ABC", 10)          ' "ABC" - entire string
Debug.Print Left("Test", 4)          ' "Test" - exact length
' Example 3: Zero length
Debug.Print Left("Hello", 0)         ' "" - empty string
' Example 4: Extract file extension check
Dim fileName As String
fileName = "C:\Data\file.txt"
If Left(fileName, 3) = "C:\" Then
    Debug.Print "File on C: drive"
End If

Common Patterns

' Pattern 1: Extract first N characters
Function GetPrefix(text As String, length As Long) As String
    If length <= 0 Then
        GetPrefix = ""
    Else
        GetPrefix = Left(text, length)
    End If
End Function
' Pattern 2: Truncate with ellipsis
Function Truncate(text As String, maxLength As Long) As String
    If Len(text) <= maxLength Then
        Truncate = text
    Else
        Truncate = Left(text, maxLength - 3) & "..."
    End If
End Function
' Pattern 3: Check if string starts with prefix
Function StartsWith(text As String, prefix As String) As Boolean
    StartsWith = (Left(text, Len(prefix)) = prefix)
End Function
' Pattern 4: Extract first word
Function GetFirstWord(text As String) As String
    Dim spacePos As Long
    spacePos = InStr(text, " ")
    If spacePos > 0 Then
        GetFirstWord = Left(text, spacePos - 1)
    Else
        GetFirstWord = text
    End If
End Function
' Pattern 5: Extract initials
Function GetInitials(fullName As String) As String
    Dim parts() As String
    Dim i As Long
    Dim initials As String
    parts = Split(Trim(fullName), " ")
    initials = ""
    For i = LBound(parts) To UBound(parts)
        If Len(parts(i)) > 0 Then
            initials = initials & UCase(Left(parts(i), 1))
        End If
    Next i
    GetInitials = initials
End Function
' Pattern 6: Safe Left with Null check
Function SafeLeft(value As Variant, length As Long) As String
    If IsNull(value) Then
        SafeLeft = ""
    Else
        SafeLeft = Left(value, length)
    End If
End Function
' Pattern 7: Extract drive letter
Function GetDriveLetter(path As String) As String
    If Len(path) >= 2 And Mid(path, 2, 1) = ":" Then
        GetDriveLetter = Left(path, 2)
    Else
        GetDriveLetter = ""
    End If
End Function
' Pattern 8: Pad left to fixed width
Function PadLeft(text As String, width As Long, Optional padChar As String = " ") As String
    If Len(text) >= width Then
        PadLeft = Left(text, width)
    Else
        PadLeft = String(width - Len(text), padChar) & text
    End If
End Function
' Pattern 9: Extract area code from phone
Function GetAreaCode(phone As String) As String
    Dim digitsOnly As String
    Dim i As Long
    Dim char As String
    ' Extract digits only
    digitsOnly = ""
    For i = 1 To Len(phone)
        char = Mid(phone, i, 1)
        If char >= "0" And char <= "9" Then
            digitsOnly = digitsOnly & char
        End If
    Next i
    ' Get first 3 digits as area code
    If Len(digitsOnly) >= 3 Then
        GetAreaCode = Left(digitsOnly, 3)
    Else
        GetAreaCode = ""
    End If
End Function
' Pattern 10: Create abbreviation
Function Abbreviate(text As String, maxLength As Long) As String
    If Len(text) <= maxLength Then
        Abbreviate = text
    Else
        ' Take first letter of each word
        Dim words() As String
        Dim i As Long
        Dim abbr As String
        words = Split(text, " ")
        abbr = ""
        For i = LBound(words) To UBound(words)
            If Len(words(i)) > 0 Then
                abbr = abbr & UCase(Left(words(i), 1))
                If Len(abbr) >= maxLength Then Exit For
            End If
        Next i
        Abbreviate = abbr
    End If
End Function

Advanced Usage Examples

' Example 1: Fixed-width file parser
Public Class FixedWidthParser
    Private m_fieldLengths() As Long
    Public Sub SetFieldLengths(ParamArray lengths() As Variant)
        Dim i As Long
        ReDim m_fieldLengths(LBound(lengths) To UBound(lengths))
        For i = LBound(lengths) To UBound(lengths)
            m_fieldLengths(i) = CLng(lengths(i))
        Next i
    End Sub
    Public Function ParseLine(line As String) As Variant
        Dim fields() As String
        Dim i As Long
        Dim pos As Long
        ReDim fields(LBound(m_fieldLengths) To UBound(m_fieldLengths))
        pos = 1
        For i = LBound(m_fieldLengths) To UBound(m_fieldLengths)
            If pos <= Len(line) Then
                fields(i) = Trim(Mid(line, pos, m_fieldLengths(i)))
            Else
                fields(i) = ""
            End If
            pos = pos + m_fieldLengths(i)
        Next i
        ParseLine = fields
    End Function
    Public Function GetField(line As String, fieldIndex As Long) As String
        Dim pos As Long
        Dim i As Long
        pos = 1
        For i = LBound(m_fieldLengths) To fieldIndex - 1
            pos = pos + m_fieldLengths(i)
        Next i
        If pos <= Len(line) Then
            GetField = Trim(Mid(line, pos, m_fieldLengths(fieldIndex)))
        Else
            GetField = ""
        End If
    End Function
End Class
' Example 2: Text preview/truncation utility
Public Class TextPreview
    Public Function CreatePreview(text As String, maxLength As Long, _
                                  Optional ellipsis As String = "...") As String
        If Len(text) <= maxLength Then
            CreatePreview = text
            Exit Function
        End If
        ' Try to break at word boundary
        Dim truncated As String
        Dim lastSpace As Long
        truncated = Left(text, maxLength - Len(ellipsis))
        lastSpace = InStrRev(truncated, " ")
        If lastSpace > maxLength \ 2 Then
            ' Break at word if space found in second half
            CreatePreview = Left(truncated, lastSpace - 1) & ellipsis
        Else
            ' Break at character
            CreatePreview = truncated & ellipsis
        End If
    End Function
    Public Function WordWrap(text As String, lineWidth As Long) As String
        Dim result As String
        Dim remaining As String
        Dim line As String
        Dim spacePos As Long
        result = ""
        remaining = text
        Do While Len(remaining) > lineWidth
            ' Try to break at word
            line = Left(remaining, lineWidth)
            spacePos = InStrRev(line, " ")
            If spacePos > 0 Then
                result = result & Left(line, spacePos - 1) & vbCrLf
                remaining = Mid(remaining, spacePos + 1)
            Else
                result = result & line & vbCrLf
                remaining = Mid(remaining, lineWidth + 1)
            End If
        Loop
        result = result & remaining
        WordWrap = result
    End Function
End Class
' Example 3: Code prefix analyzer
Public Class CodeAnalyzer
    Private m_prefixes As Collection
    Private Sub Class_Initialize()
        Set m_prefixes = New Collection
    End Sub
    Public Sub RegisterPrefix(prefix As String, description As String)
        m_prefixes.Add Array(prefix, description), prefix
    End Sub
    Public Function GetCodeType(code As String) As String
        Dim i As Long
        Dim prefix As Variant
        Dim info As Variant
        For i = 1 To m_prefixes.Count
            info = m_prefixes(i)
            prefix = info(0)
            If Left(code, Len(prefix)) = prefix Then
                GetCodeType = info(1)
                Exit Function
            End If
        Next i
        GetCodeType = "Unknown"
    End Function
    Public Function ExtractPrefix(code As String, prefixLength As Long) As String
        ExtractPrefix = Left(code, prefixLength)
    End Function
    Public Function StripPrefix(code As String, prefixLength As Long) As String
        If Len(code) > prefixLength Then
            StripPrefix = Mid(code, prefixLength + 1)
        Else
            StripPrefix = ""
        End If
    End Function
End Class
' Example 4: String comparison helper
Public Class StringComparer
    Public Function StartsWith(text As String, prefix As String, _
                               Optional ignoreCase As Boolean = False) As Boolean
        Dim textPrefix As String
        Dim comparePrefix As String
        If Len(prefix) = 0 Then
            StartsWith = True
            Exit Function
        End If
        If Len(text) < Len(prefix) Then
            StartsWith = False
            Exit Function
        End If
        textPrefix = Left(text, Len(prefix))
        If ignoreCase Then
            StartsWith = (LCase(textPrefix) = LCase(prefix))
        Else
            StartsWith = (textPrefix = prefix)
        End If
    End Function
    Public Function GetCommonPrefix(str1 As String, str2 As String) As String
        Dim i As Long
        Dim minLen As Long
        minLen = IIf(Len(str1) < Len(str2), Len(str1), Len(str2))
        For i = 1 To minLen
            If Left(str1, i) <> Left(str2, i) Then
                If i = 1 Then
                    GetCommonPrefix = ""
                Else
                    GetCommonPrefix = Left(str1, i - 1)
                End If
                Exit Function
            End If
        Next i
        GetCommonPrefix = Left(str1, minLen)
    End Function
    Public Function RemovePrefix(text As String, prefix As String, _
                                 Optional ignoreCase As Boolean = False) As String
        If StartsWith(text, prefix, ignoreCase) Then
            RemovePrefix = Mid(text, Len(prefix) + 1)
        Else
            RemovePrefix = text
        End If
    End Function
End Class

Error Handling

Left handles several special cases:

' Empty string
Debug.Print Left("", 5)              ' "" - empty string
' Zero length
Debug.Print Left("Hello", 0)         ' "" - empty string
' Length exceeds string
Debug.Print Left("Hi", 10)           ' "Hi" - entire string
' Null propagates
Dim value As Variant
value = Null
Debug.Print IsNull(Left(value, 3))   ' True
' Negative length causes error
' Debug.Print Left("Test", -1)       ' Error 5: Invalid procedure call
' Safe pattern with error handling
Function SafeLeft(text As Variant, length As Long) As String
    On Error Resume Next
    If IsNull(text) Then
        SafeLeft = ""
    ElseIf length < 0 Then
        SafeLeft = ""
    Else
        SafeLeft = Left(text, length)
    End If
    On Error GoTo 0
End Function

Performance Considerations

Fast Operation: Left is a very fast intrinsic function
String Creation: Creates new string (strings are immutable)
Left$ Variant: Use Left$ for String return type (slightly faster)
Repeated Calls: Cache result if using same substring multiple times Performance tips:

' Efficient for single use
If Left(fileName, 2) = "C:" Then
' Cache if used multiple times
Dim prefix As String
prefix = Left(code, 3)
If prefix = "ABC" Or prefix = "DEF" Then

Best Practices

Validate Length: Ensure length is non-negative
Null Safety: Check for Null before calling Left if needed
StartsWith Pattern: Use Left for prefix checking
Truncation: Consider word boundaries when truncating display text
Use Left$: For String variables, use Left$ for type safety
Combine with Len: Check string length before extracting
Fixed-Width Data: Use Left for fixed-width field extraction
Path Manipulation: Use Left for drive/path prefix extraction

Function	Purpose	Parameters	Use Case
`Left`	Extract from left	`(string, length)`	Get prefix/first N chars
`Right`	Extract from right	`(string, length)`	Get suffix/last N chars
`Mid`	Extract from middle	`(string, start, [length])`	Get substring from any position
`InStr`	Find substring	`([start,] string1, string2)`	Locate substring position
`Len`	Get string length	`(string)`	Measure string

Left vs Mid

Dim text As String
text = "Hello World"
' Left - simpler for leftmost characters
Debug.Print Left(text, 5)            ' "Hello"
' Mid - equivalent but more verbose
Debug.Print Mid(text, 1, 5)          ' "Hello"
' Use Left for clarity when extracting from start
' Use Mid when start position is not 1

Left, Right, and Mid Together

Dim text As String
text = "ABCDEFGH"
' Left - first 3 characters
Debug.Print Left(text, 3)            ' "ABC"
' Right - last 3 characters
Debug.Print Right(text, 3)           ' "FGH"
' Mid - middle characters
Debug.Print Mid(text, 3, 4)          ' "CDEF"
' Combine for complex extraction
Dim part As String
part = Left(Right(text, 5), 2)       ' "DE"

Platform and Version Notes

Available in all VB6 versions
Part of VBA core functions
Returns Variant containing String (Left$ returns String type)
Maximum string length is approximately 2GB (theoretical)
Practical limit is much lower due to memory constraints

Limitations

Cannot extract from right side (use Right function)
Cannot extract from middle with offset (use Mid function)
Negative length raises error (not treated as 0)
Creates new string (cannot modify in place)
No option for character vs byte extraction
No built-in word boundary awareness

Right: Extract characters from right side of string
Mid: Extract substring from any position
Len: Get length of string
InStr: Find position of substring
Trim/LTrim/RTrim: Remove whitespace