Help me to find out what is wrong with this code

[vermarajeev]

Hello everybody,
This is my second query in this post. Firstly thankx to Banfa, for helping me solve my first query.

Here is the code which I have written.

#include<iostream>
#include<fstream>
using namespace std;
 
class myClass
{
public:
    myClass(){}
    friend std::istream& operator>>(std::istream& i, myClass& ct);
    std::istream& extractor(std::istream& i);
};
 
std::istream& myClass::extractor(std::istream& i)
{
    char line[256];
    char keyword[64];
    char origKeyword[64];
    int  p;
    char cp;
    bool finished = false;
    bool endct = false;    
 
    while( i && !finished )
        {
            if( (p = i.peek()) == ';' || p == '#' )
            {
            // read the comment line and discard it
            i.getline( line, 255 );
            continue;
            }        
            // check for eof or error
            if( !i )
                continue;
            while( i && isspace( p = i.peek() ) )
            {
            i.get(cp);
            }
            // check for error or eof
            if( !i )
                continue;
 
            if( !endct )
            {
            // check for a digit, and if we don't get one it means we
            // are done with tablecounting
                if( ( p = i.peek() ) != EOF && isdigit( p ) )
                {
                    i.getline(line, sizeof(line));    
                    continue;
                }
                else
                {
                // this is the end of the connection table proper
                endct = true;
                }
            }
 
            if( ( p = i.peek() ) != EOF && isalpha( p ) )
            {
            // read the keyword, and deal with the input
            i >> origKeyword;
            // make a copy of the keyword, in case we need to put it back in the stream
            strcpy( keyword, origKeyword );
            // change to lower case
            for( char *lp = keyword; *lp; ++lp )
            {
            *lp = tolower( *lp );
            }
            if( i )
                {
                    if( !strncmp( keyword, "cis", 3 ) )
                    {
                        i.getline(line, sizeof(line));
                    }
                    else if( !strncmp( keyword, "trans", 5 ) )
                    {
                        i.getline(line, sizeof(line));
                    }
                    else if( !strncmp( keyword, "entgegen", 8 ) )
                    {
                        i.getline(line, sizeof(line));
                    }
                    else if( !strncmp( keyword, "zusammen", 8 ) )
                    {
                        i.getline(line, sizeof(line));
                    }
                    else if( !strncmp( keyword, "chiral", 6 ) )
                    {
                        i.getline(line, sizeof(line));
                    }
                    else if( !strncmp( keyword, "donttouch", 9 ) )
                    {
                        i.getline(line, sizeof(line));
                    }
                    else if( !strncmp( keyword, "startwith", 9 ) )
                    {
                        i.getline(line, sizeof(line));
                    }
                    else if( !strncmp( keyword, "keybond", 7 ) )
                    {
                        i.getline(line, sizeof(line));
                    }
                    else if( !strncmp( keyword, "planetrans", 10 ) )
                    {
                        i.getline(line, sizeof(line));
                    }
                    else if( !strncmp( keyword, "planecis", 8 ) )
                    {
                        i.getline(line, sizeof(line));
                    }
                    else if( !strncmp( keyword, "available", 9 ) )
                    {
                        i.getline(line, sizeof(line));
                    }
                    else
                    {
                        int len = strlen( origKeyword );
                        for(char c = origKeyword[len-1]; len>0; --len)
                        {
                            c = origKeyword[len - 1];                            
                            i.putback(c);
                        }
                        finished = true;
                    }
                }//if i
                continue;
            }
 
        if( EOF == i.peek() )
            break;
        }//while
        return i;
}
 
std::istream& operator>>(std::istream& i, myClass& ct)
{
    return ct.extractor( i );
}
 
bool loadFile( std::istream &i )
{
    if(i)
    {
        int ii = 1;
        char line[256];
        int  p;
        char cp;        
        bool finished = false;
        int  routesw = 2;        // routesw == 2 means the beginning of the file
 
        int  ctsw = 0;
        int  infosw = 0;        
        myClass* ct = NULL;
 
        while( i && !finished )
            {
                if( (p = i.peek()) == ';' || p == '#' )
                {
                // read the comment line and discard it
                i.getline( line, sizeof() );
                continue;
                }
 
                // check for eof or error
                if( !i )
                    continue;
 
                // If we haven't reached EOF, read the line, and parse.
                // Otherwise break the loop and finish.
                // The getline() function reads to the '\n' (or sizeof(line) - 1),
                // discards it, and appends a '\0' to the line.
                if( ( p = i.peek() ) != EOF )
                {
                    i.getline( line, sizeof(line) );
                    cout<<line<<endl;    
                    if(ii == 4017)
                    {
                        cout<<ii<<endl;
                    }
                    ii++;
                }
                else
                    break;
                if(i)
                {
                    if( strstr(line,"CONNECTION TABLE") )
                    {
                        // The connection table starts on the next line,
                        // and so we read it here. 
                        // skip blank space at the beginning of the line
                        while( i && isspace( p = i.peek() ) )
                        {
                            i.get(cp);
                        }
 
                        // check for error or eof
                        if( !i )
                            continue;
 
                        // Check for a digit, meaning we are about to read a 
                        // ConnectionTable.  Only allocate a new ct if we
                        // are not at EOF and the next line begins with a digit.
                        if( ( p = i.peek() ) != EOF && isdigit( p ) )
                        {
                            // Allocate a new connection table
                            ct = new myClass;                                        
                             i >> *ct;                                        
                        }
                        i.clear();
                        // if we are at EOF then break
                        if( EOF == i.peek() )
                        {
                            finished = true;
                            break;
                        }
                    }                    
                } //if(i)
                // check whether we are at the end of the file
            if( EOF == i.peek() )
                break;
            }//while
    return true;
    }//if(i)
    return false;
}
 
int main(int argc, char* argv[])
{
    ifstream t("eugene.ct.syn", std::ios::in );
    if(t)
    {
        t.seekg( 0, std::ios::beg );
        if(loadFile( t ))
        {
            cout<<"File loaded completely"<<endl;
        }
        else
            cout<<"File failed to load"<<endl;
    }
    t.close();
 
    return 0;
}

Please dont get scared with the size of the code. I'm trying to read a file called "eugene.ct.syn" (given below as attached file). Now I want to read the entire file from starting till end. When I run this code on Visual C++ Editor, the program doesnt read the entire file, but I get the message "File loaded completely" written in main. Finally the program throws an exception at the end. I want to read the entire file. If you open the file with Microsoft word you can see some text contents in it. My target is to read the file till "THE PROGRAM HAS NOW FINISHED THE PROBLEM." (which you can see in the file(eugene.ct. syn) given below as attchment after you open it). I'm attaching the program too for you easiness.
Also I'm not able to guess why this program throws an exception.

Thankx in advance,
Rajeev

[MrJay]

I'm still waiting for any suggestions.

Thanks

[Banfa]

My thoughts, without getting into too much detail, is that the structure of your code is wrong. You clearly can not unget so many characters so you will need to re-write the code so that this is not required for it to work.

I would not give control of reading a file to a sub-object if that sub-object is not able to detect the end of it's own data and instead ends up reading the data for the start of the next object. I would leave control in the main loop when the start of a new object can be handled correctly.

[MrJay]

Please elaborate, I'm unable to get what you meant.

[vermarajeev]

Hi,
Please help me to solve that problem.

I'm in a big trouble.

[Banfa]

Sorry this must have slipped through the net.

What I mean is at the moment you code effective trys this

OPEN FILE
 
LOOP
  LOAD DATA
  IF OBJECT FOUND CALL OBJECT LOAD DATA FUNCTION
UNTIL NO MORE DATA
 
CLOSE FILE
 

and OBJECT LOAD DATA FUNCTION does this

LOOP
  LOAD DATA
  IF PART OF THIS OBJECT
    STORE DATA
  ELSE
    PUT DATA BACK   // This is not working
  ENDIF
UNTIL START OF NEXT OBJECT FOUND
 

The problem is that the PUT DATA BACK section of your code is not working and this is not necessarily because the code is wrong but because the underlying system just can not do what you are asking.

You need to change this structure to something that does not rely on being able to put back the data, more like this

OPEN FILE
 
LOOP
  LOAD DATA
 
  IF DATA START OF OBJECT
    CREATE NEW OBJECT
    STORE DATA IN OBJECT
  ELSE IF DATA PART OF CURRENT OBJECT
    STORE DATA IN OBJECT
  ELSE
    DISCARD DATA  // or do something else with it
  ENDIF
UNTIL NO MORE DATA
 
CLOSE FILE
 

This code structure does not try to PUT BACK DATA and therefore will not run into the same problem. I don't think it is good practice to have an object read it's own data unless it can reliably detect the end of it's own data without having to read the next object.

[vermarajeev]

Thankx Banfa,
I'll start my implementation very soon. If any problem I'll let you know.

Rajeev

[vermarajeev]

After a long thinking, I partially got what you are talking about.
As per my understanding, I need to create an object of class istream, assign value of original istream into this newly created one and then read the first keyword then check all the "if else" blocks then finally return the original istream in the else block which in code seems to be like this

OPEN FILE
 
LOOP
  LOAD DATA
 
  IF DATA START OF OBJECT
    CREATE NEW OBJECT
    STORE DATA IN OBJECT
  ELSE IF DATA PART OF CURRENT OBJECT
    STORE DATA IN OBJECT
  ELSE
    DISCARD DATA  // or do something else with it
  ENDIF
UNTIL NO MORE DATA
 
CLOSE FILE

OPEN FILE //eg. istream i("filename");
 
LOOP
  LOAD DATA    //eg. i>>keyword;
 
  IF DATA START OF OBJECT 
    CREATE NEW OBJECT    //eg.istream& iss = i;
    STORE DATA IN OBJECT //eg. iss>>keyword;
  ELSE IF DATA PART OF CURRENT OBJECT
    STORE DATA IN OBJECT  //eg iss>>keyword
  ELSE
                   //eg. return i; //which will return original object of istream
    DISCARD DATA  // or do something else with it
  ENDIF
UNTIL NO MORE DATA
 
CLOSE FILE

If this is what you are talking about then bad luck, it still doesnt work. And if you are thinking something else please use (eg.) to give example of each step.

thanks.

[vermarajeev]

Can you guys help????

Thankx

[Banfa]

OPEN FILE //eg. istream i("filename");
 
LOOP
  LOAD DATA    //eg. i>>keyword;
 
  IF DATA START OF OBJECT 
    CREATE NEW OBJECT    //eg.istream& iss = i;
    STORE DATA IN OBJECT //eg. iss>>keyword;
  ELSE IF DATA PART OF CURRENT OBJECT
    STORE DATA IN OBJECT  //eg iss>>keyword
  ELSE
                   //eg. return i; //which will return original object of istream
    DISCARD DATA  // or do something else with it
  ENDIF
UNTIL NO MORE DATA
 
CLOSE FILE

If this is what you are talking about then bad luck, it still doesnt work.

No that is quite what I was thinking of, you have too many istreams. Using the 2 classes

istream - the input stream
myClass - class to hold the data in the file (defined in your original code)

then this is more what I had in mind

OPEN FILE //eg. istream i("filename");
 
LOOP
  LOAD DATA FROM FILE   //eg. i>>keyword;
 
  IF DATA START OF OBJECT 
    CREATE NEW OBJECT OF myClass   //eg. myObj = new myClass
    STORE DATA IN OBJECT OF myClass //eg. keyword >> myObj
  ELSE IF DATA PART OF CURRENT OBJECT
    STORE DATA IN OBJECT OF myClass //eg keyword >> myObj
  ELSE
    DISCARD DATA  // or do something else with it forget data in keyword
  ENDIF
UNTIL NO MORE DATA
 
CLOSE FILE  //eg. close i