Count Number of Letters in a String - Delphi

Question

I am creating a program where it will be necessary to show the amount of letters (A, b, C ..Z; a..z, à,â,ã) present in a String.

I’m using the following code:

function ContarLetras(Str: String): Integer;
var
    Ret, i: Integer;
begin
  Ret:=0;
  Str:= AnsiUpperCase(Str);
    for i:=1 to length(str) do
    if Str[i] in ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'] then
       begin
       Inc(Ret);
       ContarLetras:=Ret;
       end;
end;

But when running the program a number is displayed that has nothing to do with counting (e.g.: 79649600).

I wonder where the mistake might be?

Answer 1

To solve your problems with the special characters, you can declare Unit "System.Character" and change its function to:

function ContarLetras(Str: String): integer;
var
  umChar: char;
begin
  result := 0;
  for umChar in Str do
    if IsLetter(umChar) then
      Inc(result);
end;

Answer 2

There are many unnecessary variables in your code when you declare a function is required to determine the type of return (in your case is Integer). The Delphi automatically creates a variable in the scope of function calling for Result and its type is the same as the return. So you only need this variable and one more to make the increment in the for.

Ansiuppercase:

This function causes all characters to be replaced by their uppercase version. When you do Str[1] is returned a Char and the comparison between Char is key sensitive, ie will differentiate uppercase and lowercase.

Inc:

This function sums and assigns the new value to the variable passed, when you do not pass the second parameter that is the number that will be added, it assumes that this number is 1. I have a certain schism with this function I’ve had problems with it, but when I solve it uses itthere I make a point to pass the second parameter even if it is 1, to avoid problems.

Below is an example that worked well:

uses
  SysUtils;

function ContarLetras(Str: String): Integer;
var
  i: Integer;
begin
  Result := 0;
  for i:=1 to length(str) do
    if Str[i] in ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'] then
      Inc(Result);
end;

begin
  Writeln(IntToStr(ContarLetras('aa11')));
  Readln;
end.

Answer 3

Well, two things I think are not right (1) is you convert to uppercase and compare with lowercase characters, and (2) the return should be set out of the loop.

Since I haven’t worked with Delphi in years, I can’t test it, but see if that’s it:

function ContarLetras(Str: String): Integer;
var
    Ret, i: Integer;
begin
  Ret:=0;
  Str:= AnsiUpperCase(Str);
  for i:=1 to length(str) do
  begin
    if Str[i] in ['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'] then
    begin
      Inc(Ret);
    end;
  end;
  ContarLetras:=Ret;
end;