How to remove space around a character? - string

Question

Say I have the following string:
s := 'This , is, the Delphi , World!';
I would like the following output:
Result := 'This,is,the Delphi,World!';
Basically I need a routine that strips ALL occurrences of spaces ONLY if they appears before or after the comma char (which is my delimiter), leaving intact spaces between other words.
Any help is much appreciated.
What do you think of this solution?
function RemoveSpacesAroundDelimiter(var aString: string; aDelimiter:
string): string;
begin
while AnsiContainsText(aString, aDelimiter + ' ') do
begin
aString := StringReplace(aString, ', ', aDelimiter, [rfReplaceAll, rfIgnoreCase]);
end;
while AnsiContainsText(aString, ' ' + aDelimiter) do
begin
aString := StringReplace(aString, ' ' + aDelimiter, aDelimiter, [rfReplaceAll, rfIgnoreCase]);
end;
Result := aString;
end;
thanks
fabio

Answer 1

Sounds like a task for TStringList.
function UltraTrim(Value: string): string;
var
sl: TStringList;
i: Integer;
begin
sl := TStringList.Create;
try
// Prevent the stringlist from using spaces as delimiters too.
sl.StrictDelimiter := True;
// Set the comma separated text.
sl.CommaText := Value;
// Trim each item.
for i := 0 to sl.Count -1 do
sl[i] := Trim(sl[i]);
// Concat back to comma separated string.
Result := sl.CommaText;
finally
sl.Free;
end;
end;

Answer 2

A fast version could be:
function RemoveSpacesAroundDelimiter(const aString: string; aDelimiter: char = ','): string;
var S, D, D2: PChar;
begin
SetLength(result,length(aString));
if aString<>'' then
begin
S := pointer(aString);
D := pointer(result);
while S^<>#0 do
begin
if S^=' ' then
begin
D2 := D;
repeat
inc(S);
D^ := ' ';
inc(D);
until S^<>' ';
if S^=#0 then
break;
if S^=aDelimiter then
D := D2; // trim spaces before comma
end;
D^ := S^;
if (S[0]=aDelimiter) and (S[1]=' ') then
repeat inc(S) until S^<>' ' else // trim spaces after comma
inc(S);
inc(D);
end;
SetLength(result,D-pointer(result));
end;
end;
Some test code:
assert(RemoveSpacesAroundDelimiter('one two,three')='one two,three');
assert(RemoveSpacesAroundDelimiter('one two , three')='one two,three');
assert(RemoveSpacesAroundDelimiter('one,two,three')='one,two,three');
assert(RemoveSpacesAroundDelimiter('one , two, three')='one,two,three');

Answer 3

Copy characters one-by-one into the destination buffer, but look for spaces and delimiters, and remember the last location you copied a non-space character into. If you see a space and the last non-space you copied was the delimiter, then skip the space. If it's a space and the last character you copied wasn't the delimiter, then copy it to the destination, but remember the last non-space you added. That way, if you see a delimiter later, you can go back and overwrite it.
function RemoveSpacesAroundDelimiter(const AString: string; ADelimiter: Char): string;
var
c: Char;
dest: Integer;
LastNonSpace: Integer;
HaveDelimiter: Boolean;
begin
Assert(ADelimiter <> ' ');
SetLength(Result, Length(AString));
dest := 1;
LastNonSpace := 0;
HaveDelimiter := False;
for c in AString do begin
if (c = ' ') and HaveDelimiter then
continue; // Skip this character
if c = ADelimiter then begin
dest := LastNonSpace + 1;
HaveDelimiter := True;
end else
HaveDelimiter := False;
Result[dest] := c;
if c <> ' ' then
LastNonSpace := dest;
Inc(dest);
end;
SetLength(Result, dest - 1);
end;

Answer 4

If you are using Delphi XE or above you can do this trivially in a single line of code, using a regular expression.
program regex;
{$APPTYPE CONSOLE}
uses
RegularExpressions;
const
Input = 'This , is, the Delphi , World!';
begin
Writeln(TRegEx.Replace(Input, ' *, *', ','));
Readln;
end.
Naturally this is not the fastest running of the solutions on offer, but maybe that doesn't matter to you.

Answer 5

You can use regular expressions. You want to find the delimiter preceded or followed by any number of spaces, and replace it all with a single copy of the delimiter.
function RemoveSpacesAroundDelimiter(const AString: string; const ADelimiter: string): string;
var
re: TPerlRexEx;
begin
re := TPerlRegEx.Create;
try
re.RegEx := '\s*' + TPerlRegEx.EscapeRegExChars(ADelimiter) + '\s*';
re.Subject := AString;
re.Replacement := TPerlRegEx.EscapeRegExChars(ADelimiter);
re.ReplaceAll;
Result := re.Subject;
finally
re.Free;
end;
end;
Newer Delphi versions can use the built-in RegularExpressionCore unit. Older versions can use the equivalent PerlRegEx unit from Jan Goyvaerts.
Mick previously posted an answer demonstrating this, but he deleted it because he got the regular expression wrong (deleting all spaces instead of just the ones abutting the delimiter).

Answer 6

The simpler and easiest way is to use regular expressions. The last thing you would need is a huge complicated code block to solve such a simple problem. Unfortunatly I don't have Delphi with me right now, I can't test this code, but if it's nothing exactly like this, it's very very close:
s := 'This , is, the Delphi , World!';
RegEx := TRegEx.Create('[ ]*,[ ]*');
CleanStr := RegEx.Replace(s, ',');

Answer 7

I have this solution:
slValores.DelimitedText := StringReplace(sListSummary,' ','',[rfReplaceAll]);

Answer 8

I thought this was worth adding because it will work with early versions of Delphi, which the stringlist solution (which I liked) does not.
It is alo reasonably quick, I believe, and fairly simple to read and understand.
function TForm1.UltraTrim(const InString : String; Delim : Char) : String;
var
Buf : String;
i : Integer;
Token : String;
begin
Result := '';
if Trim(InString) <> '' then begin
i := 1;
Buf := StringReplace(InString, Delim, #0, [rfReplaceAll]) + #0;
while i < Length(Buf) do begin
Token := StrPas(#Buf[i]);
i := i + Length(Token) + 1;
Result := Result + Delim + Trim(Token);
end;
Result := Copy(Result,2,Length(Result));
end;
end;

Answer 9

Using Jedi Code Library, answer by #GolezTrol can be reformulated using one-liner.
function UltraTrim(Value: string): string;
begin
Result := JclStringList.Split(Value, ',').Trim.Join(',')
end;
http://en.wikipedia.org/wiki/Fluent_interface
http://wiki.delphi-jedi.org/wiki/JCL_Help:JclStringList

Answer 10

with this function :
function MBTrim(iStr :string):string;
const CTc= 3{Conditions Count};
CT :array[0..(CTc-1),0..1]of string= ( (' ,', ','), (', ', ','), (' ', ' ') );
var i :Integer;
begin
for i := 0 to CTc-1 do while Pos(CT[i,0], iStr) > 0 do
iStr:= StringReplace(iStr, CT[i,0], CT[i,1], [rfReplaceAll, rfIgnoreCase]);
Result:= Trim(iStr);
end;
you can add other conditions simply.
for example i add (' ', ' ') to convert space between words like :
'This , is, the Delphi , World!'

Answer 11

Changed, one more time.
while (pos(', ',s)>0) or (pos(' ,',s)>0) do begin
s := StringReplace(s, ', ', ',', [rfReplaceAll]);
s := StringReplace(s, ' ,', ',', [rfReplaceAll]); end;
OK for all the Delphi versions.