FileWrite - does not add text into the end of file, but replaces the content of CSV file, why?

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I need to add some information into the end of CSV or TXT file, but every time I open the file with FileOpen and write the text there, it erases all information and write a new text..

But I need to add the new information into the end of the file, while keeping the previous text as well. Kind of incremental approach.

I need to keep previous text after closing file with FileClose and opening again with FileOpen.

Any idea? How to get a file with increasing volume in every writing there?

Look forward to hearing from you.

Thanks.

Bahman

 
bahmanasgerov: I need to add some information into the end of CSV or TXT file, but every time I open the file with FileOpen and write the text there, it erases all information and write a new text.. But I need to add the new information into the end of the file, while keeping the previous text as well. Kind of incremental approach. I need to keep previous text after closing file with FileClose and opening again with FileOpen. Any idea? How to get a file with increasing volume in every writing there? Look forward to hearing from you. Thanks. Bahman

File Opening Flags - Input/Output Constants - Constants, Enumerations and Structures - MQL5 Reference - Reference on algorithmic/automated trading language for MetaTrader 5

One or several flags can be specified when opening a file. This is a combination of flags. The combination of flags is written using the sign of logical OR (|), which is positioned between enumerated flags. For example, to open a file in CSV format for reading and writing at the same time, specify the combination FILE_READ|FILE_WRITE|FILE_CSV.

Example:

   int filehandle=FileOpen(filename,FILE_READ|FILE_WRITE|FILE_CSV);

There are some specific features of work when you specify read and write flags:

  • If FILE_READ is specified, an attempt is made to open an existing file. If a file does not exist, file opening fails, a new file is not created.
  • FILE_READ|FILE_WRITE – a new file is created if the file with the specified name does not exist.
  • FILE_WRITE –  the file is created again with a zero size.
 
Vinicius Pereira De Oliveira #:

File Opening Flags - Input/Output Constants - Constants, Enumerations and Structures - MQL5 Reference - Reference on algorithmic/automated trading language for MetaTrader 5

Is it the answer? I caannot get the answer here)), I need some option to use to open the file with addition, not replacement or deletion.

I use this code, that does not work...

int f=FileOpen("WriteString.csv",FILE_READ|FILE_WRITE|FILE_CSV);     FileWriteString(f,"1111111....\r\n");


Thanks for your kind answer.

Maybe Fernando Carreiro?

As usual, his answers are useful))

Fernando Carreiro
Fernando Carreiro
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bahmanasgerov #: Is it the answer? I caannot get the answer here)), I need some option to use to open the file with addition, not replacement or deletion. I use this code, that does not work... int f=FileOpen("WriteString.csv",FILE_READ|FILE_WRITE|FILE_CSV);     FileWriteString(f,"1111111....\r\n"); [ . . . ]

Would you like a water or coffee while you wait?... Ask someone who knows how to read for help and see the article below... There's even the code ready:

Articles

MQL5 Programming Basics: Files

Dmitry Fedoseev, 2016.11.04 15:19

This practice-oriented article focuses on working with files in MQL5. It offers a number of simple tasks allowing you to grasp the basics and hone your skills.
See too:  File Functions - MQL5 Reference - Reference on algorithmic/automated trading language for MetaTrader 5
 
Vinicius Pereira De Oliveira #:

Would you like a water or coffee while you wait?... Ask someone who knows how to read for help and see the article below... There's even the code ready:

Thanks Viicius, I will have a look now. However, I have not transitioned to MT5 yet, I am still in MT4, let me see, if I can apply it for codes in MQL4.

Regards

Bahman

 
bahmanasgerov #: Thanks Viicius, I will have a look now. However, I have not transitioned to MT5 yet, I am still in MT4, let me see, if I can apply it for codes in MQL4. Regards Bahman

OK, if the error persists, please post your code (using the CODE button - Alt+S) so we can identify why it isn't working.

 
Vinicius Pereira De Oliveira #:

OK, if the error persists, please post your code (using the CODE button - Alt+S) so we can identify why it isn't working.

dear Vinicicus, 


Thanks for your idea, it looks now I can understand your point of view. I mean if I include READ and WRITE options, then I can read the content of the file, 

save it into a string variable and then when I need to save the file, I can add it onto the beginning of newly added text and save them into a file together?

I hope, you meant this, it was a good idea, and thanks a lot for this. It looks my problem gets solved.

Regards

Bahman

 
bahmanasgerov #:

dear Vinicicus, 


Thanks for your idea, it looks now I can understand your point of view. I mean if I include READ and WRITE options, then I can read the content of the file, 

save it into a string variable and then when I need to save the file, I can add it onto the beginning of newly added text and save them into a file together?

I hope, you meant this, it was a good idea, and thanks a lot for this. It looks my problem gets solved.

Regards

Bahman

The following function I have made to add new text onto the end of the CSV file... Thanks a lot:

LineAdd(f,"1,2,3"); //function calling...

void LineAdd(int f,string s) {while(!FileIsEnding(f))FileReadString(f); FileWriteString(f,s+"\n");return;}



 
bahmanasgerov #: The following code was enough to add new portion of text, onto the end of the CSV file... Thanks a lot: [ . . . ]

You're welcome, good luck!!

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