Thread: File Reading Errors

When I run this code:

Code:

#include <stdio.h>
#include <stdlib.h>
#include <fstream.h> 
#include <iostream.h> 
#include <time.h> 
#include <string.h>


int main()
{
	srand((unsigned)time(NULL));
	int x=rand()%9;
	ofstream value("xvalue.txt", ios::ate | ios::in, filebuf::sh_write );
	if(!value.is_open())
	{
	   cout<<"Could not open file...  Error.... Quitting\n";
	   system("PAUSE");
	   return 0;
	}
	value<<x<<";";
	value.close();
	char yes;
	cout<<"Would you like to view contents of file (up to 200 characters in)?\n y for yes, anything else for quit\n";
	cin>>yes;
	if (yes=='y' || yes== 'Y')
	{
		char text[200];
		ifstream read_value("xvalue.txt", ios::out | ios::nocreate);
		if (!read_value.is_open())
		{
			printf("Error opening file\n");
			system("PAUSE");
			return 0; 
		}
        read_value>>text;
		for (int i=0; i<=200; i++)
		printf("%c", text[i]);
		printf("\n\n");
		read_value.close();
        system("PAUSE");	
		printf("\n\nWould you like to delete the contents of the file?");
		cin>>yes;
        if (yes== 'y' || yes=='Y')
       read_value.clear(0);
 	}
	return 0;
}

I get what I want, but if I have any spaces in the file it stops reading there. Also, if I read a file it reads what's in it, and then adds some various characters. How can I fix both of these problems?

You are mixing C and C++ I/O. This is not good practice. The function printf from the stdio library is a C function. Use cout instead. The declaration of read_value(file, ios::in) to open a file is also a C type function. Use read_value.open(file, ios::in) instead.

Secondly, your app quits reading at whitespaces because the >> operator treats them as a delimiter. To avoid this use either the file.getline() or file.get() function.

Here is the reason you're getting garbage for output:

Code:

for (int i=0; i<=200; i++)
printf("%c", text[i]);

You're telling printf to output 199 chars when you have only 2 (or however many are stored in your file) stored in the array. The rest of the chars you're outputting are null characters.

Lastly, fstream.clear() doesn't delete the contents of a file like you might think it would. The clear function is actually used to clear the filestream buffer.

Take a close look at the code below. It's well commented.

Code:

//include our headers using the standard namespace
#include <cstdlib>
#include <fstream> 
#include <iostream>//exclude <stdio.h> since we're using <iostream>
#include <ctime> 
using namespace std;
//the std namespace also includes some basic 
//string functions like stricmp() and stcmp()

int main()
{	
	ofstream value;//declare our output stream
        ifstream read_value;//declare our input stream
	char yes[1];//set aside an array for yes
	int x;//for our random number

	srand((unsigned)time(NULL));
                x = rand()%9;

	value.open("xvalue.txt", ios::out | ios::app );
        //use the open function, app is preferred to ate

	if(!value.is_open())
	{
	   cout << "Could not open file...  Error.... Quitting\n";
	   exit(0);//exit if our file doesn't open
	}

	value << x << ";";

	value.close();

	cout << "Would you like to view contents of file " 
		 << "(up to 200 characters in)?\n\nY for yes, "
		 << " anything else for quit: ";

	cin >> yes;
	cin.get();
        //cin leaves the \n character in the buffer, 
        //so we call cin.get to remove it
	cout << "\n";

	if (stricmp(yes, "Y") == NULL)
        //"stricmp()" compares two character strings. 
        //Case is ignored as opposed to "strcmp()," 
        //which is case sensitive. It returns 
        //NULL or 0 if the two strings are equal.
	{	
		char text[200];
		read_value.open("xvalue.txt", ios::in );
		if (!read_value.is_open())
		{
			cout << "Error opening file\n";
			exit(0); 
		}
        read_value.getline(text, 200);
        //here we pass our character array and its size to
        //read_value.getline(). This will read characters into
        //the array until it reaches the delimiter. The delimiter
        //is set to "\n" by default but can be changed by 
        //overloading the function.

	cout << text << "\n\n";
        //output the text to the screen and we are done.
        //Good work!

	read_value.close();
	}
	
	return 0;
}

OK, that works...
But there is still one problem...
A runtime error....
After it displays the file, I get:
Run-Time Check Failure #2 - Stack around the variable 'yes' was corrupted.

And then it freezes for a while and exits.

[EDIT]
I'm am using VC++ .NET. It's being run in debug mode. When I do it in release it works just fine...

[/EDIT]

It sounds like you're exceeding the bounds of your array. Tell me if I'm wrong, but and array of size[1] has two members [0] and [1] right? So the "Y" the user enters gets stored in [0] and [1] is reserved for the null char.

Did you change the size of the "yes" array?

Perhaps try increasing the variable size of "yes" to yes[2]. Or bigger, just in case the user tries to enter garbage. Say yes[20].

Let me know if that doesn't work.

It worked, but before I was just just typing y and I got that error. Oh well, it works now. Also how would I make a sub-directory?

ex:

the .exe is at C:\MyProgs\Prog00\

and I want the text file at C:\MyProgs\Prog00\Saves

How would I do that?

It's simple

value.open("saves/xvalue.txt", ios::in | ios::app);

That's all there is to it.

To my knowledge, but don't quote me, compilers are created in assembly yes. The only langauges that are based on other langauges are called scripts. Again don't quote me.

Are you using a double forward slash like you did in the your example above? Or were you just trying to escape to back-slash in that example? It is one forward-slash between the directory and the file surrounded in quotes. At least on my compiler and system. Using VS6 on XP.

Either way, did you create a folder called "saves" and put your file in it?

The syntax for using the system command is different from opening a file, in this case you do use the escape character. You must also specify the directory where the exec is located. Unless it's in the same folder as the one you're running I think.

system("C:\\Games\\StarWarsJK2\\JediOutcast.exe");