Title: Counting occurrences in a string
Question: A function that returns the number of times a substring occurs in a string. There's also an ANSI version.
Answer:
Counting occurrences in a string
The following functions return the number of occurrences of a char or a substring within a string or ANSI string:
interface
function Occurs(const str: string; c: char): integer; overload;
function Occurs(const str: string; const substr: string): integer;
overload;
function AnsiOccurs(const str: string; const substr: string): integer;
implementation
uses sysutils;
function Occurs(const str: string; c: char): integer;
// Returns the number of times a character occurs in a string
var
p: PChar;
begin
Result := 0;
p := PChar(Pointer(str));
while p nil do begin
p := StrScan(p, c);
if p nil then begin
inc(Result);
inc(p);
end;
end;
end;
function Occurs(const str: string; const substr: string): integer;
// Returns the number of times a substring occurs in a string
var
p, q: PChar;
n: integer;
begin
Result := 0;
n := Length(substr);
if n = 0 then exit;
q := PChar(Pointer(substr));
p := PChar(Pointer(str));
while p nil do begin
p := StrPos(p, q);
if p nil then begin
inc(Result);
inc(p, n);
end;
end;
end;
function AnsiOccurs(const str: string; const substr: string): integer;
// Returns the number of times a substring occurs in a string
// ANSI version
var
p, q: PChar;
n: integer;
begin
Result := 0;
n := Length(substr);
if n = 0 then exit;
q := PChar(Pointer(substr));
p := PChar(Pointer(str));
while p nil do begin
p := AnsiStrPos(p, q);
if p nil then begin
inc(Result);
inc(p, n);
end;
end;
end;