Delphi extracts a number from a character

Function Setstring (cstring:string): string; {Extract Number}
Var
I:integer;
str:string;
Begin
Str:= ";
For i:=1 to Length (cString) does
Begin
If Pos (Cstring[i], ' 0123456789. ') <=0 Then
Break
Else
Case Cstring[i] of
'. ': str:=str+ '. ';

' 0 ': str:=str+ ' 0 '; ' 1 ': str:=str+ ' 1 '; ' 2 ': str:=str+ ' 2 ';
' 3 ': str:=str+ ' 3 '; ' 4 ': str:=str+ ' 4 '; ' 5 ': str:=str+ ' 5 ';
' 6 ': str:=str+ ' 6 '; ' 7 ': str:=str+ ' 7 ';
' 8 ': str:=str+ ' 8 '; ' 9 ': str:=str+ ' 9 ';
End
End
SETSTRING:=STR;
End

If 121545adfdf.121 is extracted after the break command is removed from the 121545 function, the result is: 121545.121

Delphi extracts a number from a character