Reading from multiple lines in a File

[logebotmaster]

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

[mattallen37]

Well, with NXC, Yes, and Yes.

[muntoo]

Hi,
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?

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

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

[muntoo]

I can't edit my post...

Anyways, here it is again:

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

Hi,
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?

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);
    }
}

[mattallen37]

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++
  }
}

[dudmaster]

[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????

[muntoo]

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????

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

Code: Select all

[spoiler][url=http://xkcd.com/109/][spoiler][img]http://imgs.xkcd.com/comics/spoiler_alert.png[/img][/spoiler][/url]

I use spoilers

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");
}

[dudmaster]

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

[muntoo]

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);

[logebotmaster]

Thanks all, very interesting indeed.
Botmaster