Vb6 utilities

VB6 Utilities Catalog

VB6 codebases typically maintain a shared utility module (commonly named modUtils, modFuncoes, modCommon, or similar) that accumulates helpers over years of development. Before writing a utility function from scratch, check whether one already exists.

This catalog describes the functions you are most likely to find. Names and exact signatures vary per project; the names below are representative of the patterns to look for.

Conventions

fg_ prefix — "function global"

Many codebases use the fg_ prefix for stateless utility functions exposed project-wide. Examples: fg_isNull, fg_Coalesce, fg_InIDE. When you see this prefix, treat the function as part of the utility layer — reusable, side-effect-free, safe to call from anywhere.

Dialog wrappers — MsgBoxXxx

Most projects wrap MsgBox to integrate with logging, theming, and consistent button layouts. Typical names: MsgBoxCritical, MsgBoxInfo, MsgBoxWarning, MsgBoxQuestion, MsgBoxOption. Use the wrapper, not raw MsgBox.

1. NULL handling

fg_isNull(value, defaultValue) As Variant

Returns defaultValue when value is Null, otherwise returns value. Equivalent to SQL's ISNULL or COALESCE with one fallback.

strName = fg_isNull(rs("custName").Value, "")
lngCount = fg_isNull(rs("total").Value, 0)

fg_Coalesce(value1, value2, ...) As Variant

Returns the first non-Null value in the list, or Null if all are Null.

strContact = fg_Coalesce(strPhone, strMobile, strEmail, "no contact")

fg_NullIf(value, valueIfEqual) As Variant

Returns the string "Null" (for SQL literal use) when value matches valueIfEqual, otherwise returns value. Used when building SQL strings manually.

fg_NullIfDB(value, valueIfEqual) As Variant

Returns actual Null (not the string "Null") when value matches valueIfEqual, otherwise returns value. Used when assigning to ADO parameter values.

2. SQL literal formatting (legacy)

ToSQL(value, [ForceString], [MaxChars]) As String

Formats any Variant as a SQL literal: dates as 'dd/mm/yyyy', numbers with . decimal separator, strings with apostrophes doubled, Null as Null.

strSQL = "INSERT INTO Customer (custName, custBirth) VALUES (" & _
         ToSQL(strName) & ", " & ToSQL(dtmBirth) & ")"

Modern code prefers parameters over ToSQL. See vb6-ado-late-binding. ToSQL remains useful for:

• Building diagnostic display SQL (e.g., ShowADOCommand output)
• Structural SQL where a single literal is concatenated for legitimate reasons
• Maintenance of existing code that uses it

SanitizeSqlString(s As String) As String

Doubles apostrophes (' → '') to prevent SQL literal breakage. Called internally by ToSQL. Direct use is mainly for backward compatibility with older code paths.

Note: sanitization is a fallback. Parameters are the correct solution.

3. String manipulation

RemoveAccents(sText As String) As String

Strips diacritical marks (á → a, ç → c, etc.) for accent-insensitive search and matching.

TrimAll(sText As String) As String

Strips all whitespace including non-breaking spaces, tabs, and CRLF — beyond what built-in Trim does.

TrimLeadingZeros(value As String) As String

Removes leading zeros from a numeric string. "00012345" → "12345".

PadLeft(sText, [sChar], [iLen]) As String

PadRight(sText, [sChar], [iLen]) As String

String padding to a target length with a fill character (default space).

strInvoiceNum = PadLeft(CStr(lngID), "0", 9)    ' "000012345"

RemoveDup(sText, sChar) As String

Collapses consecutive occurrences of sChar into one. "a,,b,,,c" → "a,b,c".

RemoveDuplicates(pText, [Delimiter]) As String

Removes duplicate entries from a delimited list. "a,b,a,c,b" → "a,b,c".

RemoveEnd(sText, [iQtChar]) As String

Removes the last N characters. Useful for trailing separators after a loop: PathBuild = PathBuild & dir & "\" then RemoveEnd(PathBuild, 1).

MidFirst(sText, sChar) As String

Returns the substring after the first occurrence of sChar.

MidLast(sText, sChar) As String

Returns the substring after the last occurrence of sChar.

SubstringBetween(sString, markStart, markEnd, [StartEnd]) As String

Returns the substring between two markers. SubstringBetween("Hello [World]!", "[", "]") → "World".

SubstringLeft(sString, markEnd) As String

Returns the substring left of the marker.

CountOccurrences(sText, sStringToCount) As Integer

Counts non-overlapping occurrences of a substring.

ReplaceBetween(Expression, FindIni, FindEnd) As String

Replaces everything between two markers (inclusive of the markers).

4. Validation

IsValidCNPJ(CNPJ As String) As Boolean

Validates a Brazilian company tax ID (CNPJ): format, length, and check digits. Accepts formatted ("12.345.678/0001-90") or unformatted ("12345678000190") input.

IsValidCPF(CPF As String) As Boolean

Validates a Brazilian personal tax ID (CPF): format, length, and check digits.

IsValidEmail(mailAddress As String) As Boolean

Validates email address format via regex.

IsNumericPad(KeyCode As Integer) As Boolean

Returns True if the key code corresponds to a numeric input (0-9, decimal, backspace, arrows). Used in KeyDown/KeyPress handlers for numeric-only text fields.

5. Format conversion

ToHour(sec As Single, [IncludeSeconds]) As String

Converts seconds to HH:MM:SS or HH:MM format.

fg_NumberToWords(nValue As Double, CurrencySingular, CurrencyPlural) As String

Renders a numeric value as written-out currency ("one hundred and twenty-three reais and forty-five cents").

Trunc(value, DecimalPlaces As Byte) As Currency

Truncates a number to N decimal places (no rounding).

RoundOrTrunc(value, DecimalPlaces As Byte) As Currency

Truncates or rounds based on a project-wide setting (gParameters.RoundOrTruncate).

ApplyFiscalRounding(dblTotalValue, [decimalPlaces]) As Double

Applies fiscal rounding rules (banker's rounding or specific Brazilian fiscal conventions).

6. Encryption (lightweight, not for security)

Encrypt(Input As String) As String

Decrypt(Input As String) As String

Symmetric scrambling for storing low-stakes values (window position, recent file list) in INI files. Not cryptographically secure — do not use for passwords or sensitive data.

fg_EncryptKey(sKey As String) As String

Project-specific key encoding for connection strings stored in config files.

7. Dialog wrappers

MsgBoxCritical(Text As String)

Critical error dialog. Always logged with Force = True.

MsgBoxInfo(Text As String)

Informational dialog. Logged at normal level.

MsgBoxWarning(Text As String, [returnValue], [YesNoButtons]) As VbMsgBoxResult

Warning dialog with optional OK-only or Yes/No buttons.

MsgBoxQuestion(Text, [DefaultButton], [YesNoButtons], ...) As VbMsgBoxResult

Yes/No confirmation dialog.

MsgBoxOption(Text, Option1, Option2, ...) As Byte

Two-button choice dialog with custom button captions.

Rule: new code never calls MsgBox directly. Always use the wrapper.

8. Environment detection

fg_InIDE() As Boolean

Returns True when running inside the VB6 IDE, False when running as a compiled EXE. Classic implementation triggers Debug.Print 1/0 which raises in IDE but is removed by the compiler.

Public Function fg_InIDE() As Boolean
    On Error GoTo erro
    Static blnCached As Boolean
    Static blnComputed As Boolean
    
    If blnComputed Then
        fg_InIDE = blnCached
        Exit Function
    End If
    
    Debug.Print 1 / 0           ' raises in IDE, removed by compiler
    blnCached = False
    blnComputed = True
    fg_InIDE = False
    Exit Function
erro:
    blnCached = True
    blnComputed = True
    fg_InIDE = True
End Function

9. UI helpers

CenterObject(o As Object)

Centers a form or control within its container.

FocusOn(ctl As Object, [SelectText As Boolean])

Sets focus to a control with optional auto-selection of contents.

PopulateCombo(cbo As ComboBox, rs As Object, [defaultID])

Populates a ComboBox from a Recordset (column 0 as value, column 1 as display).

LV_ColumnSort(ListView, ...)

Generic ListView column sort handler.

ListViewLineColor(lvw, ItemIndex, ToColor)

Sets a row's background color in a ListView.

ListViewToJson(lvw, [useItemKey]) As String

Exports a ListView's contents as JSON for persistence or transport.

LoadListViewFromJson(lvw, sJSON As String)

Imports a ListView from a JSON string previously produced by ListViewToJson.

10. Serialization (for logging/debugging)

Serialize(Fields As Variant) As String

Generic serializer that handles arrays, Dictionaries, Recordsets, and Field collections. Returns a delimited string for logging.

SerializeForm(frm As Object, [HumanReadable]) As String

Iterates a form's controls and serializes their current values. Useful in error handlers to capture the UI state at the moment of failure.

SerializeListItem(lstView, lstItem) As String

SerializeListGrid(lstView, [lRow]) As String

ListView and grid row serialization.

11. Date helpers

LastDayOfMonth(iMonth, iYear) As Integer

Returns the last day of a given month.

12. File system

CreateFolder(DestDir As String) As Boolean

Creates a directory tree (recursive), returning True on success.

13. Regex

RegExp(sPattern As String, sText As String, ...) As ...

Wraps VBScript.RegExp (late-bound) for regex matching. Useful when the project does not want a reference to the Regex type library.

14. Other

EvaluateVBCode(Scode As String)

Late-bound MSScriptControl.ScriptControl evaluation. Use cautiously — this is eval for VB6 and carries the same risks.

GetSeqNumber() As String

Returns a project-wide unique sequence number (timestamp-based or counter-based depending on implementation).

Soundex(sText As String) As String

Phonetic encoding for fuzzy name matching.

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Pre-flight check before writing a new utility

Before adding a new helper function, look for an existing one:

• Searched for fg_<thing> in the utility module
• Searched for <Thing> (PascalCase) in the utility module
• Searched for the operation by description (e.g., "remove accent", "validate cnpj", "format hour")
• Asked whether the codebase has a consistent place for this kind of helper (modUtils, modFuncoes, modString, etc.)

If the helper does not exist, follow the project's naming conventions (fg_ prefix or not, English or Portuguese, the file the helper belongs in) when adding it.