How to resolve the algorithm Strip whitespace from a string/Top and tail step by step in the Oberon-2 programming language

Published on 12 May 2024 09:40 PM
#Oberon-2

How to resolve the algorithm Strip whitespace from a string/Top and tail step by step in the Oberon-2 programming language

Table of Contents

Problem Statement

Demonstrate how to strip leading and trailing whitespace from a string. The solution should demonstrate how to achieve the following three results:

For the purposes of this task whitespace includes non printable characters such as the space character, the tab character, and other such characters that have no corresponding graphical representation.

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Strip whitespace from a string/Top and tail step by step in the Oberon-2 programming language

Source code in the oberon-2 programming language

MODULE Trim;
IMPORT Out,Strings,SYSTEM;

CONST
	(* whitespaces *)
	HT = 09X;	VT = 0BX;	FF = 0CX;	GS = 1DX;	US = 1FX;
	LF = 0AX;	CR = 0DX; 	FS = 1CX;	RS = 1EX;	SPC = 20X;
	
PROCEDURE LTrim(VAR s: ARRAY OF CHAR);
VAR 
	j : INTEGER;
BEGIN
	j := 0;
	WHILE (s[j] = HT) OR (s[j] = LF) OR (s[j] = VT) OR (s[j] = CR) OR 
		(s[j] = FF) OR (s[j] = FS) OR (s[j] = FS) OR (s[j] = GS) OR
		(s[j] = RS) OR (s[j] = US) OR (s[j] = SPC) DO INC(j) END;
	SYSTEM.MOVE(SYSTEM.ADR(s[j]),SYSTEM.ADR(s[0]),LEN(s) - j);
END LTrim;

PROCEDURE RTrim(VAR s: ARRAY OF CHAR);
VAR
	j : INTEGER;
BEGIN
	j := LEN(s) - 1;
	WHILE (j >= 0) & (s[j] = 0X) DO DEC(j) END;
	WHILE (j >= 0) & ((s[j] = HT) OR (s[j] = LF) OR (s[j] = VT) OR (s[j] = CR) OR 
		(s[j] = FF) OR (s[j] = FS) OR (s[j] = FS) OR (s[j] = GS) OR
		(s[j] = RS) OR (s[j] = US) OR (s[j] = SPC)) DO 
		s[j] := 0X;
 		DEC(j)
	END
END RTrim;

PROCEDURE Trim(VAR s: ARRAY OF CHAR);
BEGIN 
	LTrim(s);
	RTrim(s)
END Trim;

VAR
	s: ARRAY 100 OF CHAR;
	
BEGIN
	s := "   A AAA";
	Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);LTrim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln;
	s := "AAA A    ";
	Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);RTrim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln;
	s := "   A AA A   ";
	Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);Trim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln;
	s := "    ";
	Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);Trim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln;
	s := "    ";
	Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);RTrim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln;
	s := "    ";
	Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);LTrim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln;
	Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);RTrim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln;
	Out.Char("[");Out.String(s);Out.String("]=");Out.Char(HT);LTrim(s);Out.Char("[");Out.String(s);Out.Char("]");Out.Ln;
END Trim.

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