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Posted: **21 Dec 2010, 20:02**

Hi,
Okay, I know how to write multiple lines into a file on the NXT, and it's proven very helpful in creating readable .txt datalogs. What my question is, is it possible for the NXT to retrieve information from a file in any of the written lines instead of just the last recorded line? And also, is it possible to accurately retrieve data from a .txt file? Thanks
Botmaster

Posted: **21 Dec 2010, 20:51**

Well, with NXC, Yes, and Yes.

Posted: **21 Dec 2010, 21:33**

Matt, I think that the OP was also asking "how".

Assuming it's in string format, you may want to check out ReadLnString().

Posted: **21 Dec 2010, 21:43**

I can't edit my post...

Anyways, here it is again:

@Matt, I think that the OP was also asking "how".

Assuming it's in string format, you may want to check out ReadLnString().

I believe it works like this:

Code: Select all

void ReadLines(string &out[], string filename)
{
    byte handle;
    unsigned int fsize;

    ArrayInit(out, "", 0);

    if(OpenFileRead(filename, fsize, handle) == LDR_SUCCESS)
    {
        // Yes, I know I'm becoming more and more like the guys at IOCCC
        for(string szBuf; (ReadLnString(handle, szBuf) == LDR_SUCCESS); ArrayBuild(out, out, szBuf));

        CloseFile(handle);
    }
}

Posted: **21 Dec 2010, 21:53**

I suppose you are likely right. Here is an example of the method I use.

Code: Select all

if(OpenFileRead("File.txt", size, handle) == NO_ERR)
{
  until (Sdone == true)  // read the text file till the end
  {
    if(ReadLnString(handle,message) != NO_ERR) Sdone = true;
    //You need to grab the message and write it to another string(or whatever you need to do) all right here.
    //Base it on an increasing variable, like the following lines.
    TotalMessage[i]=message;
    i++
  }
}

Posted: **21 Dec 2010, 23:56**

[quotename=mattallen]

Code: Select all

if(OpenFileRead("File.txt", size, handle) == NO_ERR)
{
  until (Sdone == true)  // read the text file till the end
  {
    if(ReadLnString(handle,message) != NO_ERR) Sdone = true;
    //You need to grab the message and write it to another string(or whatever you need to do) all right here.
    //Base it on an increasing variable, like the following lines.
    TotalMessage[i]=message;
    i++
  }
}

[/quote]
I need to write this to the variable "Sen". Can you modify this
program to do this?

And how does muntoo do the "Show" thing????

Posted: **22 Dec 2010, 00:42**

One of these buttons contains the answer. Actually, they all do.

Anyways, enough fooling around before Xander gets tempted to remove the "Show button"

. Here's what you want, assuming that Sen is an array of strings:

Code: Select all

void ReadLines(string &out[], string filename)
{
    byte handle;
    unsigned int fsize;

    ArrayInit(out, "", 0);

    if(OpenFileRead(filename, fsize, handle) == LDR_SUCCESS)
    {
        // Yes, I know I'm becoming more and more like the guys at IOCCC
        for(string szBuf; (ReadLnString(handle, szBuf) == LDR_SUCCESS); ArrayBuild(out, out, szBuf));

        CloseFile(handle);
    }
}


task main()
{
    string Sen[];
    ReadLines(Sen, "File.txt");
}

Posted: **22 Dec 2010, 02:27**

Sen is a string (not array). I like your idea. Thanks... half

Posted: **23 Dec 2010, 04:23**

dudmaster wrote:Sen is a string (not array). I like your idea. Thanks... half

If Sen is JUST a string, I don't get why you don't just do this:

Code: Select all

OpenFileRead(fname, fsize, handle);
Read(handle, Sen);
//Or if that doesn't work:
ReadBytes(handle, fsize, Sen);
//Or
char cSen[];
ReadBytes(handle, fsize, cSen);
CloseFile(handle);

Posted: **28 Dec 2010, 22:41**

Thanks all, very interesting indeed.
Botmaster

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Reading from multiple lines in a File

Reading from multiple lines in a File

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Re: Reading from multiple lines in a File