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Pascal and Delphi Discussion Thread
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Mar 18th, 2009

Parsing a string. Need help

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Hello,
I am new to delphi. I have a problem. I have a string which can be of any length. Sometimes with delimiter characters for printing in new line.
Now I need to distinguish whether the received string is a number (both -ve and +ve) or any other alpha numeric value. Based on that I need to proceed further.
Any built in function to check this? or how to parse and find out its a number?

regards,
Anand

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anandkrishnantc

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Mar 18th, 2009

Re: Parsing a string. Need help

There are a number of conversion functions the sysutils.pas unit that can test this for you and check out extractstrings in the Classes unit for a basic parsing function.

jsosnowski

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Mar 19th, 2009

Re: Parsing a string. Need help

I'm not good in delphi...but I want to help you
I looked for you problem on the web,and there was a good idea for your problem.They say:Try to convert that string into number.The StrToIntDef takes an extra argument that is returned, if the string could not be converted to int successfully.

Last edited by FlamingClaw; Mar 19th, 2009 at 10:28 am.

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Mar 19th, 2009

Re: Parsing a string. Need help

Or a simple try... except...end block such as

Pascal and Delphi Syntax (Toggle Plain Text)
function IsInteger(MyString:string):boolean;
begin
  try
    Result:=true;
    strtoint(MyString);
  except
    Result:=false;
  end;
end;
function IsInteger(MyString:string):boolean;
begin
  try
    Result:=true;
    strtoint(MyString);
  except
    Result:=false;
  end;
end;

IntToStrDef sounds easier.

Last edited by m610; Mar 19th, 2009 at 1:32 pm.

m610

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Mar 19th, 2009

Re: Parsing a string. Need help

By the way, I had not known about the StrToIntDef function until reading this thread. I checked with Help in my copy of Delphi 6, which is where I have learned most of my Delphi programming, and it did not list it. Then I looked in SysUtils.pas and found it, along with some other nice functions I wish I had known about, such as:

function StrToFloatDef(const S: string; const Default: Extended): Extended;

and

function TryStrToFloat(const S: string; out Value: Extended): Boolean;

I'll be digging around in there a bit more for other things I have missed, like the string-to-int function that converts strings, including hex-formatted strings, to integers.

m610

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Mar 23rd, 2009

Re: Parsing a string. Need help

Hello, thanks for the replies. I have a text (Widestring). Which need to be checked (no need or converting it ), if its a float or not. When I tried TexttoFloat, the program behaves worgly. No proper ending of the method.
and I see all the text ends with #0 . should I remove this trailing #0 ?

anandkrishnantc

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Mar 23rd, 2009

Re: Parsing a string. Need help

Click to Expand / Collapse Quote originally posted by m610 ...

Or a simple try... except...end block such as
Pascal and Delphi Syntax (Toggle Plain Text)
function IsInteger(MyString:string):boolean;
begin
  try
    Result:=true;
    strtoint(MyString);
  except
    Result:=false;
  end;
end;
function IsInteger(MyString:string):boolean; begin try Result:=true; strtoint(MyString); except Result:=false; end; end;
IntToStrDef sounds easier.

It worked. thanks.

anandkrishnantc

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