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Nov 25th, 2008

Re: fstream problem.

Still can't figure it out.

imput1234

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Nov 25th, 2008

Re: fstream problem.

What about..this...

c++ Syntax (Toggle Plain Text)
//...
fin.open(ifile);
if(fin.fail())
   std::cout<<"does not exist";
//...
//...
fin.open(ifile);
if(fin.fail())
   std::cout<<"does not exist";
//...

cikara21

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Solved Threads: 69

Posting Whiz

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340 posts
since Jul 2008

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Nov 25th, 2008

Re: fstream problem.

every text should cover this

C++ Syntax (Toggle Plain Text)
fin.open ( "somefile.txt" );
if( !fin )  // or   if( fin.fail( ) )
{
     //error handler  goes here
}
else
{
    //file opened successfully, start reading
}
fin.open ( "somefile.txt" );
if( !fin )  // or   if( fin.fail( ) )
{
     //error handler  goes here
}
else
{
    //file opened successfully, start reading
}

vmanes

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Posting Virtuoso

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since Aug 2007

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Nov 25th, 2008

Re: fstream problem.

Click to Expand / Collapse Quote originally posted by imput1234 ...

Nevermind, weird it works now. I havent;' made any changes.

But I do have another problem.

I'm trying to make the program so that, if the user does not enter a valid file name, it will output that and clsoe the program.

This is what I have so far, and no matter what the user enters, the console will go in to a failstate. Anyone know why

Thanks.
(Toggle Plain Text)
	ifstream fin;

	cout << "Enter filename: ";
	getline(cin, ifile);	

    
	if ( !ifile.size() == 0 )
	{	
		cout << "No file found." << endl;
		system ("PAUSE");
		return 1;
	}

	fin.open(ifile.c_str());
ifstream fin; cout << "Enter filename: "; getline(cin, ifile); if ( !ifile.size() == 0 ) { cout << "No file found." << endl; system ("PAUSE"); return 1; } fin.open(ifile.c_str());

just try this one...........................

(Toggle Plain Text)

	ifstream fin;

	cout << "Enter filename: ";
	getline(cin, ifile);	
        fin.open(ifile.c_str());
       
	 if(fin.fail())
	{	
		cout << "No file found." << endl;
		system ("PAUSE");
		return 1;
	}

	fin.open(ifile.c_str());

rajenpandit

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Dec 9th, 2008

Re: fstream problem.

Hey guys,

I'm working on another program, and have run in to another problem.

Basically for this program, I read and extract information from a file. I do not know when the file is going to end, so I used a while loop to get my data.

This is all I have done, haven't proceeded since the loop doesn't work.
Hey guys,

I'm working on another program, and have run in to another problem.

Basically for this program, I read and extract information from a file. I do not know when the file is going to end, so I used a while loop to get my data.

This is all I have done, haven't proceeded since the loop doesn't work.

(Toggle Plain Text)

void extract ( string file_name, ifstream& fin )
{
	int i = 0;
	string temp;

	
	fin.open( file_name.c_str( ) );
	fin >> temp;
	cout << temp;
	
	while ( !fin.eof( ) )//THIS PART DOES NOT WORK I've also tried while (fin) while (!fin.fail( )) can't seem to get it to work
	{
		//STUFF
	
	}

What I want it to do is end the program, when there is no more info in the file.

Thanks.

imput1234

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Dec 10th, 2008

Re: fstream problem.

alright I figured that out.

It seems as though that method will only work when followed by

fin >> somevariable;

is there anyway I can use getline (fin, string);

instead?

Thanks.

imput1234

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Dec 10th, 2008

Re: fstream problem.

while ( getline ( fin, str ) )
{
//do any other processing
}

If the read action is successful, you enter the loop body. If the read action fails, loop ends.

vmanes

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Solved Threads: 228

Posting Virtuoso

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1,895 posts
since Aug 2007

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Dec 10th, 2008

Re: fstream problem.

I'm seem to have a LOT of problems with this program.
The loop issue is fixed, now it will not read all the numbers that exist.

The Main:

(Toggle Plain Text)

	string file1, temp[1000];
	float n1[1000], n2[1000];
	int i = 1, t;

	ifstream fin;
	ofstream out;
	
	cout << "\t\t Welcome to Grade Calculator!\n\n";
	cout << "What file has your scores on it: ";
	getline( cin, file1 );
	
	fin.open( file1.c_str( ) );
	out.open( "results.html" );

	if ( fin.fail( ) ||  file1.size( ) == 0 )
	{
		cout << "No file was found or entered." << endl;
		system ("PAUSE");
		return 1;
	}

	out << "<html>" << endl;
	out << "<body>" << endl;
	out << "<pre>"  << endl;
	out << "\t\tGrade Report" << endl;
	out << "Activity     Your Grade       Possible" << endl;

	while ( getline ( fin, temp[i] ) )
	{
		fin >> n1[i] >> n2[i];
		i++;
	}

	while ( i != 0 )
	{
		if (temp[i] == "end")
		{
			out << "Percentage" << setw(13) << getpart(fin, temp[i-1].substr(0, ' ')) << endl;
		}
		else if ( n1[i] != -1 || n2[i] != -1 )
		{
			out << setw(11) << temp[1] << setw(14) << n1[i] << setw(16) << n2[i] << endl;
		}

		i--;
	}

	out << "</html>" << endl;
	out << "</body>" << endl;
	out << "</pre>" << endl;

	fin.close( );
	out.close( );

	system ("PAUSE");

	return 0;

The getpart function

(Toggle Plain Text)

float getpart (ifstream& fin, string label)
{
	string temp;
	float score = 0, total = 0, average, tem, n1, n2; 
	
	while (getline ( fin, temp ) ) 
	{
		if (temp != "end")
			if (temp.substr( ) == label)
			{
				fin >> n1 >> n2;
				score = score + n1;
				total = total + n2;
			}
	}

	average = score / total;
	
	return average;
}

The file it is reading from

(Toggle Plain Text)

Quiz 1
3 5
Quiz 2
4 10
Attd. 11-23
10 10
Quiz 3
5 5
end
-1 -1
Lab 1
10 100
Lab 2
20 20
Lab 3
30 130
end
-1 -1
Test 1
145 150
Test 2
200 210
end
-1 -1
Program 1
40 50
Program 2
90 100
Program 3
100 100
Program 4
90 100
end
-1 -1
Lab Test 1
35 50
Lab Test 2
25 50
end
-1 -1
Final Exam
234 400
end
-1 -1

Basically what the program does is organize the grades in another file .html
ie
Quiz 1 score total
and then calculate the percent in the end of each section
Percent: 100

Last edited by imput1234; Dec 10th, 2008 at 9:11 pm.

imput1234

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Dec 10th, 2008

Re: fstream problem.

I ran some tests, and it looks like the array is only storing 2 variables, of which the first one is correct the second is wrong.

this is the part where I actually store information, anyone know whats wrong?

Thanks.

(Toggle Plain Text)

	while ( getline ( fin, temp[i] ) )
	{
		fin >> n1[i] >> n2[i];
		i++;
	}

imput1234

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