Find and Count Words in a String in Delphi? - string

Question

I have a string comprising numerous words. How do I find and count the total amount of times that a particular word appears?
E.g "hello-apple-banana-hello-pear"
How would I go about finding all the "hello's" in the example above?
Thanks.

Answer 1

In Delphi XE you can use StrUtils.SplitString.
Something like this
var
Words: TstringDynArray;
Word: string;
WordCount: Integer;
begin
WordCount := 0;
Words := SplitString('hello-apple-banana-hello-pear', '-');
for Word in Words do
begin
if Word = 'hello' then
inc(WordCount);
end;

Answer 2

This would depend entirely on how you define a word and the text from which you wish to pull the words. If a "word" is everything between spaces, or "-" in your example, then it becomes a fairly simple task. If, however, you want to deal with hyphenated words, abbreviations, contractions, etc. then it becomes a lot more difficult.
More information please.
EDIT: After rereading your post, and if the example you give is the only one you want, then I'd suggest this:
function CountStr(const ASearchFor, ASearchIn : string) : Integer;
var
Start : Integer;
begin
Result := 0;
Start := Pos(ASearchFor, ASearchIn);
while Start > 0 do
begin
Inc(Result);
Start := PosEx(ASearchFor, ASearchIn, Start + 1);
end;
end;
This will catch ALL instances of a sequence of characters.

Answer 3

I'm sure there is plenty of code around to do this sort of thing, but it's easy enough to do it yourself with the help of Generics.Collections.TDictionary<K,V>.
program WordCount;
{$APPTYPE CONSOLE}
uses
SysUtils, Character, Generics.Collections;
function IsSeparator(const c: char): Boolean;
begin
Result := TCharacter.IsWhiteSpace(c);//replace this with whatever you want
end;
procedure PopulateWordDictionary(const s: string; dict: TDictionary<string, Integer>);
procedure AddItem(Item: string);
var
Count: Integer;
begin
if Item='' then
exit;
Item := LowerCase(Item);
if dict.TryGetValue(Item, Count) then
dict[Item] := Count+1
else
dict.Add(Item, 1);
end;
var
i, len, Start: Integer;
Item: string;
begin
len := Length(s);
Start := 1;
for i := 1 to len do begin
if IsSeparator(s[i]) then begin
AddItem(Copy(s, Start, i-Start));
Start := i+1;
end;
end;
AddItem(Copy(s, Start, len-Start+1));
end;
procedure Main;
var
dict: TDictionary<string, Integer>;
pair: TPair<string, Integer>;
begin
dict := TDictionary<string, Integer>.Create;
try
PopulateWordDictionary('hello apple banana Hello pear', dict);
for pair in dict do
Writeln(pair.Key, ': ', pair.Value);
finally
dict.Free;
end;
end;
begin
try
Main;
except
on E: Exception do
Writeln(E.ClassName, ': ', E.Message);
end;
end.
Output:
hello: 2
banana: 1
apple: 1
pear: 1
Note: I'm working with Delphi 2010 and don't have SplitString() available.

Answer 4

A very clever implementation I saw somewhere on the web:
{ Returns a count of the number of occurences of SubText in Text }
function CountOccurences( const SubText: string;
const Text: string): Integer;
begin
if (SubText = '') OR (Text = '') OR (Pos(SubText, Text) = 0) then
Result := 0
else
Result := (Length(Text) - Length(StringReplace(Text, SubText, '', [rfReplaceAll]))) div Length(subtext);
end; { CountOccurences }