Why do I have an OBOB error?

Code:

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void get_numbers(char *data_array, int& num_amount, ifstream& fin){
        int num; //used for temporary storage of a number obtained through the input stream
        int index = 1;  //this is to be used to begin storing data into data_array[1] below
        char comma_discard;  //used to disregard commas in the code file
        clrscr();
       
        while (!fin.eof()){
                fin >> num;
                cout << num;
                //*(data_array + index) = num;
                //cout << int(*(data_array + index)) << " ";
                num_amount++;
                index++;
                fin.get(comma_discard);
                cout << comma_discard;
               
        }
        getch();
       
} //end void get_numbers

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Contents of what the input stream is connected to:

Code:

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115,73,24,807,37,52,49,17,31,62,647,22,7,15,140,47,29,107,79,84,56,239,10,26,811,5,196,308,85,52,160,136,59,211,36,9,46,316,554,122,106,95,53,58,2,42,7,35,122,53,31,82,77,250,196,56,96,118,71,40,287,28,353,37,1005,65,147,807,24,3,8,12,47,43,59,807,45,316,101,41,78,154,1005,122,138,191,16,77,49,102,57,72,34,73,85,35,371,59,196,81,92,191,106,273,60,394,620,270,220,106,388,287,63,3,6,191,122,43,234,400,106,290,314,47,48,81,96,26,115,92,158,191,110,77,85,197,46,10,113,140,353,48,120,106,2,607,61,420,811,29,125,14,20,37,105,28,248,16,159,7,35,19,301,125,110,486,287,98,117,511,62,51,220,37,113,140,807,138,540,8,44,287,388,117,18,79,344,34,20,59,511,548,107,603,220,7,66,154,41,20,50,6,575,122,154,248,110,61,52,33,30,5,38,8,14,84,57,540,217,115,71,29,84,63,43,131,29,138,47,73,239,540,52,53,79,118,51,44,63,196,12,239,112,3,49,79,353,105,56,371,557,211,505,125,360,133,143,101,15,284,540,252,14,205,140,344,26,811,138,115,48,73,34,205,316,607,63,220,7,52,150,44,52,16,40,37,158,807,37,121,12,95,10,15,35,12,131,62,115,102,807,49,53,135,138,30,31,62,67,41,85,63,10,106,807,138,8,113,20,32,33,37,353,287,140,47,85,50,37,49,47,64,6,7,71,33,4,43,47,63,1,27,600,208,230,15,191,246,85,94,511,2,270,20,39,7,33,44,22,40,7,10,3,811,106,44,486,230,353,211,200,31,10,38,140,297,61,603,320,302,666,287,2,44,33,32,511,548,10,6,250,557,246,53,37,52,83,47,320,38,33,807,7,44,30,31,250,10,15,35,106,160,113,31,102,406,230,540,320,29,66,33,101,807,138,301,316,353,320,220,37,52,28,540,320,33,8,48,107,50,811,7,2,113,73,16,125,11,110,67,102,807,33,59,81,158,38,43,581,138,19,85,400,38,43,77,14,27,8,47,138,63,140,44,35,22,177,106,250,314,217,2,10,7,1005,4,20,25,44,48,7,26,46,110,230,807,191,34,112,147,44,110,121,125,96,41,51,50,140,56,47,152,540,63,807,28,42,250,138,582,98,643,32,107,140,112,26,85,138,540,53,20,125,371,38,36,10,52,118,136,102,420,150,112,71,14,20,7,24,18,12,807,37,67,110,62,33,21,95,220,511,102,811,30,83,84,305,620,15,2,108,220,106,353,105,106,60,275,72,8,50,205,185,112,125,540,65,106,807,188,96,110,16,73,32,807,150,409,400,50,154,285,96,106,316,270,205,101,811,400,8,44,37,52,40,241,34,205,38,16,46,47,85,24,44,15,64,73,138,807,85,78,110,33,420,505,53,37,38,22,31,10,110,106,101,140,15,38,3,5,44,7,98,287,135,150,96,33,84,125,807,191,96,511,118,440,370,643,466,106,41,107,603,220,275,30,150,105,49,53,287,250,208,134,7,53,12,47,85,63,138,110,21,112,140,485,486,505,14,73,84,575,1005,150,200,16,42,5,4,25,42,8,16,811,125,160,32,205,603,807,81,96,405,41,600,136,14,20,28,26,353,302,246,8,131,160,140,84,440,42,16,811,40,67,101,102,194,138,205,51,63,241,540,122,8,10,63,140,47,48,140,288,

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Problem is, an extra "288," is being read in at the very end and I do not know why. Technically once that last fin.get() eats that last comma shouldn't that be eof?

what's the other function do?

also, try just removing the extra comma

>>while (!fin.eof()){
classic problem, I believe. You be better off checking the return code from the reading function to see if you're at the end of the file. Or at least checking the file status after each read.

The problem is some systems don't recognise EOF until they've hit it, which in your code is too late.

It makes no sense... there is no reason why it should be getting that value twice

it's becuase it doesn't get read in the second time...and just keeps the value. instead of an error when the program tries to read nothing, it just keeps the same value for the variable, and it's printed twice thusly

Why won't it read the eof?

Quote:

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Originally posted by Nakeerb
It makes no sense... there is no reason why it should be getting that value twice

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Code:

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while (!fin.eof()){
                fin >> num;
                cout << num;

---

Say the stream has just read the last lot of input from the file, enough to satisfy the fin.get(comma_discard); call. It goes to the top of the loop and says am I at EOF? Well, I haven't got there yet, so continue with the loop. fin>>num then attempts a read and finds there's no input left, and this is when EOF is set. Next, you blindly cout<<num for the second time and so on. I've seen this work two different ways on two compilers...

Try adding a test after the fin>>num line, and if the file stream is at EOF, break out of the loop.

fix: remove the last comma :)

This is a school assignment and the text must remain untouched

To Hammer: I see, so technically it must "read the eof marker" first? Hmmm, perhaps I should reverse my loop a bit and perhaps put the fin >> stuff at the end and put one extra fin >> BEFORE the loop?

Code:

---

void get_numbers(char *data_array, int& num_amount, ifstream& fin){
        int num; //used for temporary storage of a number obtained through the input stream
        int index = 1;  //this is to be used to begin storing data into data_array[1] below
        char comma_discard;  //used to disregard commas in the code file
        clrscr();
       
        fin >> num;
       
        while (!fin.eof()){
                cout << num;
                //*(data_array + index) = num;
                //cout << int(*(data_array + index)) << " ";
                num_amount++;
                index++;
                fin.get(comma_discard);
                cout << comma_discard;
                fin >> num;
               
        }
        getch();
       
} //end void get_numbers

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Thanks Hammer! That explanation really helped me

Of course, now I get access violation errors when I remove the comments for the *data_array stuff

*(data_array + index) = num;
is bad

should be
variable = statement...

not
variable + variable = something

if you want num assigned to data_array + index then...
num = data_array + index;

i think you want

data_array[index] = num;

>*(data_array + index) = num;
is a problem, but not because of the addition. Remember that data_array is a char pointer, so adding index to it is valid. A problem will come about when trying to store the int num variable into a one character element of the array.

Code:

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void get_numbers(char (*data_array)[2], int& num_amount, ifstream& fin){
        int num; //used for temporary storage of a number obtained through the input stream
        int index = 1;  //this is to be used to begin storing data into data_array[1] below
        char comma_discard;  //used to disregard commas in the code file
        clrscr();
       
        fin >> num;  //get first data item
       
        while (!fin.eof()){  //while the eof marker has not yet been read
                *(*(data_array + index)) = num;
                cout << int(*(*(data_array + index))) << " ";
                getch();
                num_amount++;
                index++;
                fin.get(comma_discard);  //"eats" the commas after the integer values in the code file
                fin >> num;              //get next data item
               
        }
       
        getch();
       
} //end void get_numbers

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Works to an extent but then it becomes garbled and I get access violation errors

What are you trying to do? You cannot store an int in a char (unless you want to loose a load of data).

It wants me to use a two-dimensional array of chars and then use pointers to traverse the list.

I need to be able to read in every number into one row of an array, and the other row must contain the first letter of every word in another file.

However, I *could* use two arrays, an int array for the numbers and a char array for the letters, but the teacher had mentioned something about using a two-dimensional, so :/

what crazy teacher would assign such a thing requiring such strange datastructures.

ok so for numbers and characters....

in C++ i know this:

if ('A' == 65)

will evaluate to true

I *think* you can set
char bleh = 65;
and
cout<<bleh;

and have it print 'A'

but I don't remember (summer makes me forget everything :) )

That is true, but I need it the other way around. Putting integers into char arrays

doesn't this work?

char bleh[2];

bleh[0] = 65;
bleh[1] = 66;
cout<<bleh<<endl;


should print AB no?

RE: Putting integers into char arrays...

You're best served doing it the other way around. Don't put a larget data type into a smaller data type. It is bad design. If your teacher marks you down for it, tell them it's bad form and is error prone.

Assuming your integer values are never greater than 127, sure, use a char array. Otherwise, just do:

int array[N][2]; /*or*/
int array[2][N]; /* it's a matter of personal preference */

Where N is the number of elements you want in the array.

Use array[][0] for characters and array[][1] entries for integers (or the other way around).

Simply do:

array[SOMETHING][SOMETHING] = 'a';
or...
array[SOMETHING][SOMETHING] = 123456;

Vola.

Quzah.

Quote:

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Originally posted by Diamonds
doesn't this work?

char bleh[2];

bleh[0] = 65;
bleh[1] = 66;
cout<<bleh<<endl;


should print AB no?

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No. It shouldn't. You're treating it like a string. This not a string. It isn't null terminated. If you want it to print correctly you should do:

cout << bleh[0] << bleh[1] << endl;

Specify the cells of the array so it prints the characters seperately, or add another element to your array and have it hold the NULL so it is a valid string.

Quzah.