Clearing a csv-File

phi nuts 2012.10.25 04:08 #1

sunshineh:

Hi,

I am using this functions:

https://www.mql5.com/en/articles/1540

How should I clear the text in my csv-File?

Should I delete it and create it new, or is there a better way?

Write without read ?

sunshineh 2012.10.25 04:51 #2

I tried it that way:

int ClearFile (string path) 
  { 
    int result;
    int handle=_lopen (path,OF_WRITE);
    result=_llseek (handle,0,0);
    result=_lwrite (handle," ",1); 
    result=_lclose (handle);              
    if(result<0)  
    {
        return(-1);
    }
    return(1);
  }

But this does only overwrite the first letter.

Does it works, when I delete the file an create it.

What is, when another expert advisor want's to read the file just at this moment?

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phi nuts 2012.10.25 05:22 #3

sunshineh:

I tried it that way:

But this does only overwrite the first letter.

Does it works, when I delete the file an create it.

What is, when another expert advisor want's to read the file just at this moment?

Of course it works if you delete it first then create a new one, though other EA will have error "file not exist" when trying to open it, so other EA will have to wait for awhile and retry again later.

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sunshineh 2012.10.25 05:34 #4

Silly question, but how can I delete it??

phi nuts 2012.10.25 05:42 #5

sunshineh:
Silly question, but how can I delete it??

Silly answer : I dunno.

Sorry :(

Simon Gniadkowski 2012.10.25 06:30 #6

sunshineh:
Silly question, but how can I delete it??

How can you delete the file ? FileDelete() ?

The old trick to handling 2 applications or EAs looking at the same file was to write the file with a name of xxxx and when the file is complete to rename it to yyyyy rather than creating it with the correct name in the first place. You can't rename using standard mql4 functions but maybe you can with a kernel32 call . . . or similar.

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phi nuts 2012.10.25 06:47 #7

RaptorUK:

How can you delete the file ? FileDelete() ?

The old trick to handling 2 applications or EAs looking at the same file was to write the file with a name of xxxx and when the file is complete to rename it to yyyyy rather than creating it with the correct name in the first place. You can't rename using standard mql4 functions but maybe you can with a kernel32 call . . . or similar.

Sunshineh, was using this article https://www.mql5.com/en/articles/1540 . The file may be created outside experts/file folder.

Sunshineh, I prefer to use what you have tried there, but I guess you have to write a lot of lines :(

Simon Gniadkowski 2012.10.25 06:54 #8

phi.nuts:

Sunshineh, was using this article https://www.mql5.com/en/articles/1540 . The file may be created outside experts/file folder.

Ah . . OK :-)