Reference Page: Comparison Rules

Automatic Comparison Rules

Relationship: One-to-One / Rule: Is Value Equal Or Less

Definitions

Supported data types: String, Number, Date

Comparison of values of different data types always returns False.
Comparison of values of unsupported data types always returns False.

Data type: String

Strings are compared based on total length and encoding of each character.

Two strings are considered equal if they have equal length (same number of characters) AND all characters, compared one by one, were equal.

A string of shorter length is always considered lesser. Comparison of two strings is performed character by character up to the first character that differs. The string with the lesser character in that position is considered lesser.

Data type: Number

Numeric values are considered equal if there is no difference (near-zero-difference) between them (matters for floating point numbers with precision loss). 

A lesser value is considered lesser than a bigger one. All negative numbers are less than zero and all positive numbers. Thus, -1 is less than 100; -100 is less than -1.

The floating-point value NaN (not a number) is greater than any other numeric value and is equal to itself.

Data type: Date

Date/time values are compared per component values: Year, Month, Day, Hour, Second.

Two dates are considered equal if there is zero seconds difference between them.

A later date is considered greater than an earlier one. A date with a greater month but lesser year is considered less, and so forth.

Implementation

Public Function isValueEqualOrLess(ByVal sActualValue, ByVal sExpectedValue, ByVal sFormat)
  Dim intRC

  If Not isSameFormat(sActualValue, sExpectedValue, sFormat) Then
    isValueEqualOrLess = False
    Exit Function
  End If
 
  Select Case UCase(sFormat)
    Case "NUMBER"
     If CDbl(sActualValue) <= CDbl(sExpectedValue) Then
       isValueEqualOrLess = True
    Else
       isValueEqualOrLess = False
     End If
    Case "DATE"  
      If DateDiff("s", CDate(sActualValue), CDate(sExpectedValue)) >= 0 Then
      isValueEqualOrLess = True
     Else
      isValueEqualOrLess = False
     End If
   Case "STRING"
      intRC = StrComp(sActualValue, sExpectedValue)
      If (intRC = 0) OR (intRC = -1) Then
      isValueEqualOrLess = True
      Else
      isValueEqualOrLess = False
      End If
    Case Else 
      isValueEqualOrLess = False
  End Select
End Function

Test Code

  Log.Message("1-1 Comparison: isValueEqualOrLess")
 
  boolRC = isValueEqualOrLess(1, 1.0, "Number")
  If Not boolRC Then
    Log.Error("isValueEqualOrLess failed")
  End If
  boolRC = isValueEqualOrLess("1.0", "1", "String")
  If boolRC Then
    Log.Error("isValueEqualOrLess failed")
  End If
  boolRC = isValueEqualOrLess(1, 1.0, "Double")
  If boolRC Then
    Log.Error("isValueEqualOrLess failed")
  End If

  sValue1 = 1
  sValue2 = 1+dblNearlyZero
  boolRC = isValueEqualOrLess(sValue1, sValue2, "Number")
  If Not boolRC Then
    Log.Error("isValueEqualOrLess failed")
  End If

  sValue1 = 1
  sValue2 = 1+dblNearlyZero/10
  boolRC = isValueEqualOrLess(sValue1, sValue2, "Number")
  If Not boolRC Then
    Log.Error("isValueEqualOrLess failed")
  End If
 
  sValue1 = CDate("01/01/01")
  sValue2 = CDate("01/01/2001")
  boolRC = isValueEqualOrLess(sValue1, sValue2, "DATE")
  If Not boolRC Then
    Log.Error("isValueEqualOrLess failed")
  End If
     
  sValue1 = CDate("01/01/01")
  sValue2 = CDate("1/1/2001")
  boolRC = isValueEqualOrLess(sValue1, sValue2, "DATE")
  If Not boolRC Then
    Log.Error("isValueEqualOrLess failed")
  End If

  boolRC = isValueEqualOrLess("aaaazzzz", "zzzzaaaa", "String")
  If Not boolRC Then
    Log.Error("isValueEqualOrLess failed")
  End If
  boolRC = isValueEqualOrLess("ab", "abc", "String")
  If Not boolRC Then
    Log.Error("isValueEqualOrLess failed")
  End If
  boolRC = isValueEqualOrLess("ab ", "abc", "String")
  If Not boolRC Then
    Log.Error("isValueEqualOrLess failed")
  End If

  boolRC = isValueEqualOrLess(0, 1, "Number")
  If Not boolRC Then
    Log.Error("isValueEqualOrLess failed")
  End If
  boolRC = isValueEqualOrLess(0, dblNearlyZero, "Number")
  If Not boolRC Then
    Log.Error("isValueEqualOrLess failed")
  End If
  boolRC = isValueEqualOrLess(-1, 0, "Number")
  If Not boolRC Then
    Log.Error("isValueEqualOrLess failed")
  End If
  boolRC = isValueEqualOrLess(-10, -1, "Number")
  If Not boolRC Then
    Log.Error("isValueEqualOrLess failed")
  End If

  sValue1 = CDate("01/01/01")
  sValue2 = CDate("1/1/2002")
  boolRC = isValueEqualOrLess(sValue1, sValue2, "DATE")
  If Not boolRC Then
    Log.Error("isValueEqualOrLess failed")
  End If

  sValue1 = CDate("31/12/2050")
  sValue2 = CDate("1/1/2050")
  boolRC = isValueEqualOrLess(sValue1, sValue2, "DATE")
  If boolRC Then
    Log.Error("isValueEqualOrLess failed")
  End If