trouble reading from a file

akshay_satish · 10-16-2011, 01:18 AM

I need some suggestions here.
I have a file names abcd. Contents of the file are:

Raw File:
Unit: a1 channel:12 abcd
qwerty: 1234asdf revision:1
ver: nine rev:2

I need to read this into a string as a comma separated list;
eg:
a0: Unit: a1 channel:12 abcd, qwerty: 1234asdf, ver: nine

note that revision:1 and rev:2 are part of the final string and also note the prefix a0 in the final dest and also the Raw File: at the top of the file is not included in the final string;

As of now, I am able to read the entire contents into a string using ifstream and getline.. but yet to figure out how to add those commas. Thoughts pls.

Snark1994 · 10-16-2011, 04:22 AM

Do you want to post the code you do have? Then we can make suggestions on how to adapt that

akshay_satish · 10-16-2011, 05:17 AM

this doesnt make much of sense for my requirement, but... yet to improvise on it

Code:

int main() 
{
ifstream myfile("abcd");
string line;
if(myfile.is_open())
{
while(!myfile.eof())
{
getline(myfile, line);
while(!myfile.eof())
{
totalLine += line + ", ";
getline(myfile, line);
}
cout<<totalLine;
myfile.close();
}
else 
cout<<"unable to open file"<<endl;
}

Snark1994 · 10-16-2011, 05:31 AM

Firstly, it's best if you use (CODE)(/CODE) tags around your code (use square brackets [] not parentheses (), I only used them so it didn't think I was trying to write code

).

Secondly, you said

Quote:

As of now, I am able to read the entire contents into a string using ifstream and getline.. but yet to figure out how to add those commas. Thoughts pls.

Doesn't really look like you're doing that currently

you've still got pseudocode in your example. Take a look at this code example to see how to do the testing if your file has opened properly. You can then combine it with stringstream to put the commas in the correct places.

akshay_satish · 10-16-2011, 05:44 AM

Thanks, Kinda new to these concepts,getting my grip on it... any snippets u can share? which u can think of looking at the scenario.
I've worked a little further on my code and corrected the above one, I can now read from the file and insert commas at the right places now(except after last line which I dont want to). Can anyone tell me if theres a way to include revision:1 and rev:2 from my final string separated by only one space. Those two are screwing up my o/p

Snark1994 · 10-17-2011, 11:26 AM

You're getting closer, but you're still not posting compilable code. Well done for using the CODE tags, but if you also indented you'd be able to see where it's going wrong:

Code:

int main() {
    ifstream myfile("abcd");
    string line;
    if(myfile.is_open()) {
        while(!myfile.eof()) {
            getline(myfile, line);
            while(!myfile.eof()) {
                totalLine += line + ", ";
                getline(myfile, line);
            }
            cout<<totalLine;
            myfile.close();
    } else 
        cout << "unable to open file"<< endl;
}

You also need to add '#include's, 'using namepace std', and a bunch of variable declarations. If you post working code we'll be able to help you better 'cos we know what you're actually running, not what you think you might be running.

Finally, I don't quite understand your most recent question - do you mean you want to remove the "ver: nine" part of the file?

Hope this helps,

akshay_satish · 10-20-2011, 12:45 AM

Thank you very much for the reply.
This is my compiling code: works to a certain extent

Code:

#include<iostream>
#include<fstream>
#include<string>
using namespace std;

int main()
{
string line, totalLine = "scsi1: ";
ifstream myfile("scsiInfo");
long begin, end;
if(myfile.is_open())
{
begin = myfile.tellg();
myfile.seekg(0, ios::end);
end = myfile.tellg();

myfile.seekg(0, ios::beg);

getline(myfile, line);
line.clear();
        while(!myfile.eof())
        {
          getline(myfile, line);
          totalLine += line + ", ";
        }

size_t found1;
found1=totalLine.find('\t');
while(found1 != string::npos)
{
totalLine = totalLine.erase(found1, 2);
found1 = totalLine.find('\t', found1);
}

cout <<totalLine<< endl<< "Size is : "<< (end - begin)<< " bytes."<<endl;
myfile.close();
}
else cout<<"Unable to open file"<<endl;
return 0;
}

here my i/p file from which I have to read:

Code:

Attached devices:
Unit: a1 channel:12 abcd
qwerty: 1234asdf                     revision:1
ver: nine                            rev:2

o/p-->

Code:

scsi1: Unit: a1 channel:12 abcd, qwerty: 1234asdf revision:1, ver: nine rev:2, ,

o/p i want is->

Code:

scsi1: Unit: a1 channel:12 abcd, qwerty: 1234asdf revision:1, ver: nine rev:2

Snark1994 · 10-21-2011, 05:00 AM

Okay, there are two problems:

1) You're reading in a blank line at the end, which causes the second extra ","
2) You don't have a way of testing if you're at the last line of the file, so you don't know whether or not to add a "," at the end of the word you're adding.

(Also, I needed to change "totalLine.erase(found1,2)" into "totalLine.erase(found1,1)", but that could just be different whitespace formatting in the scsiInfo file)

The first one is easy to solve:

Code:

   ...
   while(!myfile.eof()) {
      getline(myfile, line);
      if(line != ""){      // NEW! - only adds the line if not empty
          totalLine += line + ", ";
      } 
   }
   ...

The second one is trickier. In my opinion, the best way to do it is to add the "," before you add 'line'. This way you will only ever have a comma if there is another term to add. However, you need to stop it putting a comma before the first line you add. So:

Code:

   ...
   bool firstLine = true;             //NEW 
   while(!myfile.eof()) {
      getline(myfile, line);
      if(line != ""){
          if(firstLine){             //NEW from here...  
              firstLine = false;     //so next time we'll start adding ","
          } else {
              totalLine += ", ";
          }
          totalLine += line;         //...up to here
      } 
   }
   ...

Hope this helps,

akshay_satish · 10-24-2011, 07:35 AM

Quote:

Originally Posted by Snark1994

Okay, there are two problems:

1) You're reading in a blank line at the end, which causes the second extra ","
2) You don't have a way of testing if you're at the last line of the file, so you don't know whether or not to add a "," at the end of the word you're adding.

(Also, I needed to change "totalLine.erase(found1,2)" into "totalLine.erase(found1,1)", but that could just be different whitespace formatting in the scsiInfo file)

The first one is easy to solve:

Code:

   ...
   while(!myfile.eof()) {
      getline(myfile, line);
      if(line != ""){      // NEW! - only adds the line if not empty
          totalLine += line + ", ";
      } 
   }
   ...

The second one is trickier. In my opinion, the best way to do it is to add the "," before you add 'line'. This way you will only ever have a comma if there is another term to add. However, you need to stop it putting a comma before the first line you add. So:

Code:

   ...
   bool firstLine = true;             //NEW 
   while(!myfile.eof()) {
      getline(myfile, line);
      if(line != ""){
          if(firstLine){             //NEW from here...  
              firstLine = false;     //so next time we'll start adding ","
          } else {
              totalLine += ", ";
          }
          totalLine += line;         //...up to here
      } 
   }
   ...

Hope this helps,

Hey thanks a bunch... I did a few mod's to this however as it did not work as expected. I removed the last line:
[CODE]
totalLine += line;
[CODE]
as that did not give me the right o/p and it kind of jumbled my output and did not put commas at the right place....At the end, I just go ahead and remove any trailing commas which works..

akshay_satish · 10-24-2011, 07:39 AM

I would like to ask one last thing here. If you can see below:

Code:

Unit: a1 channel:12 abcd
qwerty: 1234asdf                     revision:1
ver: nine                            rev:2

You can see fields like Unit, channel, qwerty, revision, ver and rev. Now Is there any possible way I can validate them (i.e., even if one of the above menitoned fields are not present or dont have any value associated with them, then I just need to store and empty string in totalLine). I've got every other bit in my code except for this.. Any clues pls?
Appreciated..

Snark1994 · 10-25-2011, 04:19 AM

Unless I've misunderstood your question, adding an empty string to totalLine

Code:

totalLine += ""

does absolutely nothing except perhaps use up some computer time (unless it's compiled out). Do you want to give me an example which doesn't work as you'd expect, along with expected and actual output?

akshay_satish · 10-25-2011, 04:39 AM

Quote:

Originally Posted by Snark1994

Unless I've misunderstood your question, adding an empty string to totalLine

Code:

totalLine += ""

does absolutely nothing except perhaps use up some computer time (unless it's compiled out). Do you want to give me an example which doesn't work as you'd expect, along with expected and actual output?

Thanks, I got almost what I wanted. All I wanted to know is, if theres any way I can validate those fields i mentioned above if there are any?

Snark1994 · 10-26-2011, 05:19 AM

I still don't understand what you mean by "validate those fields". Can you give an example?

akshay_satish · 10-26-2011, 11:52 PM

Quote:

Originally Posted by Snark1994

I still don't understand what you mean by "validate those fields". Can you give an example?

Like i need to check for the existense of Unit, Channel and revision and if any of them are missing or even their contents then i need to store an empty string in totalLine.

Snark1994 · 10-28-2011, 05:22 AM

So... If your input were:

Code:

Attached devices:
Unit: a1 channel:12 abcd
qwerty: 1234asdf                     revision:1
ver:                                 rev:2

you would want your output to be

Code:

scsi1: Unit: a1 channel:12 abcd, qwerty: 1234asdf revision:1, ver: rev:2

?

Is the issue that (depending on the whitespace) you get extra spaces in between 'ver' and 'rev'? If so, you just need to loop through (like you did for the tab characters) and replace 2 spaces with 1 space. If not, I can't see the problem with your output, as that is what I get when I run the code on the input...