Author: William Egge
I am sure every one at some time has wanted to use a case structure with strings
but that is not possible with delphi case structures. So this is my solution which
I have used over and over...
Answer:
I created a function called string index that returns the index of a string within
an array of strings. The function returns -1 if the string was not found and is
not case sensitive.
Usage:
Simply use like this
1
2 case StringIndex('Edit', ['Post', 'Edit', 'Cancel']) of
3 0: ; // Do somthing for Post "command"
4 1: ; // Do somthing for Edit "command"
5 2: ; // Do somthing for Cancel "command"
6 end;
7 {. }
8 {. }
9 {. }
10 or
11
12 if StringIndex('Edit', ['a', 'ab', 'rth']) = -1 then
13 // something
14 else
15 // something
StringIndex returns -1 if the string does not exist. This function is not case
sensitive.
Of course the first string 'Edit' would be some variable.
Happy Coding!
Source:
16 unit Fn_StringIndex;
17
18 interface
19 uses
20 SysUtils;
21
22 function StringIndex(const SearchString: string; StrList: array of string): Integer;
23
24 implementation
25
26 function StringIndex(const SearchString: string; StrList: array of string): Integer;
27 var
28 I: Integer;
29 begin
30 Result := -1;
31 for I := 0 to High(StrList) do
32 if CompareText(SearchString, StrList[I]) = 0 then
33 begin
34 Result := I;
35 Break;
36 end;
37 end;
38
39 end.
SOME EXAMPLES OF USAGE
I decided it would be good for me to show all the places where I have used this
function, so it is clearer the purpose I made it.
These are cuts directly from live code.
I hope this helps and maybe spark some ideas.
In this case I used it to determine my action if the OrdProp was Boolean or
WordBool
40 EnumVal := GetOrdProp(Instance, PropInfo);
41 if StringIndex(PropInfo^.PropType^^.Name, ['Boolean', 'WordBool']) <> -1 then
42 begin
43 { ... }
44 // to much to explain here
45 { ... }
46 end
47 else
48 { ... }
Here I am determining what kind of text to return based on the float type name
49
50 tkFloat: case StringIndex(Info.PropInfo^.PropType^^.Name,
51 ['Currency', 'TDateTime']) of
52 0:
53 begin
54 Result := CurrToStr(GetFloatProp(Instance, PropInfo));
55 end;
56 1: Result := DateTimeToStr(GetFloatProp(Instance, PropInfo));
57 else
58 Result := FloatToStr(GetFloatProp(Instance, PropInfo));
59 end;
60
61 //This converts a text string S to a boolean value.
62
63 function TRTTIModifier.TextToBool(S: string): Boolean;
64 begin
65 Result := StringIndex(S, ['', 'F', 'False', '0', 'No']) = -1;
66 end;
Taken from a web server application, to replace the passed tag "TagString" with
whatever its suppose to. This I think would be a must for anyone using borlands
web server architech.
67
68 procedure TSite.StateHTMLTag(Sender: TObject; Tag: TTag;
69 const TagString: string; TagParams: TStrings; var ReplaceText: string);
70 begin
71 case StringIndex(TagString,
72 ['UserID', 'UserCreationDate', 'UserSiteAccessTime', 'APPCreationDate',
73 'UserList', 'Host'])
74 of
75 0: ReplaceText := IntToStr(User.ID);
76 1: ReplaceText := DateTimeToStr(User.CreationDateTime);
77 2: ReplaceText := DateTimeToStr(User.LastUserAccess);
78 3: ReplaceText := DateTimeToStr(App.CreationDateTime) + ' RefCount=' +
79 IntToStr(App.ReferenceCount);
80 4: ReplaceText := 'User List has been disabled';
81 5: ReplaceText := App.Host;
82 end;
83 end;
Another snip from a web server app where the command was passed on the url. I am
only giving a small snip of it, but I think you get the idea.
84 else
85 case StringIndex(Command,
86 ['EDITOBJECT', 'MODIFY', 'GENFORM', 'DELETE',
87 'PREVIEW', 'EDIT', 'CREATESITE', 'Reload',
88 'CreateSubSite', 'LogOut', 'HistoryBack', 'HistoryForward',
89 'PublishSite', 'Copy']) of
90 0:
91 begin
92 Response.Content := EditObject(PassedObject, SubCommand);
93 end;
94 1:
95 begin
This is taken from a some laser controler software I wrote.... You can see that I
am determining what method to call based on the file extension.
96 procedure TBoneEditorData.LoadAnyFile(const FileName: string);
97 var
98 Ext: string;
99 begin
100 Ext := ExtractFileExt(FileName);
101 case StringIndex(Ext, ['.fmc', '.ild', '.fbz', '.fgp', '.fif']) of
102 0: LoadMotionFile(FileName);
103 1: LoadIldaFile(FileName);
104 2: LoadBonesFile(FileName);
105 3: LoadCombo(FileName);
106 4: LoadImageFile(FileName);
107 else
108 raise Exception.CreateFmt('Cannot load files of this type extension "%s"',
109 [Ext]);
110 end;
111 end;
This takes a code from a database field and converts it to an ord type
112 function TMDBSchedule.GetFrequency: TFrequency;
113 const
114 FreqArray: array[0..4] of string = ('Y', 'M', 'W', 'D', 'N');
115 var
116 FreqInput: string;
117 FreqOrd: integer;
118
119 begin
120 FreqInput := UpperCase(DataSet.FieldByName('Frequency').AsString);
121
122 FreqOrd := StringIndex(FreqInput, FreqArray);
123
124 case FreqOrd of
125 0: Result := frYearly;
126 1: Result := frMonthly;
127 2: Result := frWeekly;
128 3: Result := frDaily;
129 4: Result := frNone;
130 else
131 Result := frNone;
132 end;
133 end;
Thats all the most important stuff.... have fun!
Component Download: http://www.baltsoft.com/files/dkb/attachment/fn_stringindex.zip
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