How to resolve the algorithm Strip control codes and extended characters from a string step by step in the FreeBASIC programming language

Published on 12 May 2024 09:40 PM
#Freebasic

How to resolve the algorithm Strip control codes and extended characters from a string step by step in the FreeBASIC programming language

Table of Contents

Problem Statement

Strip control codes and extended characters from a string.

The solution should demonstrate how to achieve each of the following results:

In ASCII, the control codes have decimal codes 0 through to 31 and 127. On an ASCII based system, if the control codes are stripped, the resultant string would have all of its characters within the range of 32 to 126 decimal on the ASCII table. On a non-ASCII based system, we consider characters that do not have a corresponding glyph on the ASCII table (within the ASCII range of 32 to 126 decimal) to be an extended character for the purpose of this task.

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Strip control codes and extended characters from a string step by step in the FreeBASIC programming language

Source code in the freebasic programming language

' FB 1.05.0 Win64

Function stripControlChars(s As Const String) As String
  If s = "" Then Return ""
  Dim count As Integer = 0
  Dim strip(0 To Len(s) - 1) As Boolean
  For i As Integer = 0 To Len(s) - 1
    For j As Integer = 0 To 31
      If s[i] = j OrElse s[i] = 127 Then 
        count += 1
        strip(i) = True
        Exit For 
      End If
    Next j
  Next i

  Dim buffer As String = Space(Len(s) - count)
  count  = 0  
  For i As Integer = 0 To Len(s) - 1
    If Not Strip(i) Then
      buffer[count] = s[i]
      count += 1
    End If
  Next
  Return buffer
End Function

Function stripExtendedChars(s As Const String) As String
  If s = "" Then Return ""
  Dim count As Integer = 0
  Dim strip(0 To Len(s) - 1) As Boolean
  For i As Integer = 0 To Len(s) - 1
    For j As Integer = 128 To 255
      If s[i] = j Then 
        count += 1
        strip(i) = True
        Exit For 
      End If
    Next j
  Next i

  Dim buffer As String = Space(Len(s) - count)
  count  = 0  
  For i As Integer = 0 To Len(s) - 1
    If Not Strip(i) Then
      buffer[count] = s[i]
      count += 1
    End If
  Next
  Return buffer
End Function

Dim s  As String = !"\v\001The\t quick\255 \vbrown\127\f fox\156" 
Dim s1 As String = stripControlChars(s)
Dim s2 As String = stripExtendedChars(s)
Dim s3 As String = stripExtendedChars(s1)

' Under Windows console, code page 850 :
' "vertical tab" displays as ♂
' "form feed" displays as ♀ 
' Chr(1) displays as ☺
' Chr(127) displays as ⌂
' the other control characters do what it says on the tin 
' Chr(156) displays as £
' Chr(255) displays as space
 
Print "Before stripping   :" , s
Print "Ctl chars stripped :" , s1
Print "Ext chars stripped :" , s2
Print "Both sets stripped :" , s3
Print
Print "Before stripping"   ,  "Length => " ; Len(s)
Print "Ctl chars stripped" ,  "Length => " ; Len(s1)
Print "Ext chars stripped" ,  "Length => " ; Len(s2)
Print "Both sets stripped" ,  "Length => " ; Len(s3)
Print
Print "Press any key to quit"
Sleep

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