reading in a text file containing hex values

hi all, thankyou once agian for your help the other day, but once agian i have been banging my head against a brick wall and need to call on your wisdom.

I have a text file containing hex values of the form

12 3
24 7
23 78
10 98

(maxium of 2 hex values per colum, 8 bits but sometimes there is only one!)

where the first colum contains an address and the second a data value to be written to that address. I need to read the file into an array of the form

address[2014]
data[2014]

as their are 2014 lines of code.

my attempt so far is :-

Code:

#include <stdio.h>


void display(int a, int v)  ;

int main()

{

	FILE *file_ptr;
	int address[2014], value[2014], i, j;
	
	file_ptr = fopen("C:\\Documents and Settings\\Owner\\Desktop\\sta013.txt","rt");
	if (file_ptr !=NULL)
	{
		printf("settings file found\n");
		
		
		i=0;
		while (i<1024)
			{
				i++;
				fscanf(file_ptr,"%0x",&address[i]);
				fscanf(file_ptr,"%0x",&value[i]);
			}
			
		printf("total number of values read %d\n",i);
		for (j=0; j<i-1;j++)
			{
			
			
			display(address[j],value[j]);
			
			
			
			
			}
		fclose(file_ptr);
		return 0;
	}
	else
		printf("file not found\n");
		return 0;
}


void display(int a,int v)
{
	printf("%x	%x\n", a,v);

}

however this gives the following results

Code:

settings file found
total number of values read 2014
e7ff0010	                e7ff0010
e800e800	e800e800
e7ff0010	                e7ff0010
e800e800	e800e800
etc ...                       etc...

would really appreciate any help! this little problem is stopping my completing vital code for my thesis and i am really stressed. Unfortunately code is not my strongest point so i may have dont something silly. but please point it out.

Thankyou all.

Code:

i=0;
while (i<1024)
{
	i++;
	fscanf(file_ptr,"%0x",&address[i]);
	fscanf(file_ptr,"%0x",&value[i]);
}

You're indexing is off by one. Assuming you want to fill address[0..n] and value[0..n] try this:

Code:

i=0;
while (i<1024)
{
	fscanf(file_ptr,"%0x",&address[i]);
	fscanf(file_ptr,"%0x",&value[i]);
                i++;
}

Well, I'm pretty sure %0x means "read a hexadecimal value, but for heaven's sake don't read more than 0 characters". Does it work without the 0?

>i++;
Are you sure you want to skip the first element of the array?

>fscanf(file_ptr,"%0x",&address[i]);
>fscanf(file_ptr,"%0x",&value[i]);
This should be %x rather than %0x.

You might also note that this is essentially a for loop:

Code:

i=0;
while (i<1024)
{
	fscanf(file_ptr,"&#37;0x",&address[i]);
	fscanf(file_ptr,"%0x",&value[i]);
	i++;
}

Code:

for (i = 0; i < 1024; i++)
{
	fscanf(file_ptr,"%0x",&address[i]);
	fscanf(file_ptr,"%0x",&value[i]);
}

Hi, thanks for quick reply.

have removed the 0 from %0x, aslo have changed the location of i++; but still getting erounus output.

Code:

settings file found
total number of values read 2014
e7ff0010	e7ff0010
e800e800	e800e800
e7ff0010	e7ff0010
e800e800	e800e800

any further ideas? thankyou

Can you define the input file better please, in hex? like this:

1st pair: 0x01234568 0x0000007
2nd pair: 0x00123434 0x0000008

etc, as this format illustrates how many bytes are used by each field. Once we know the file format, we can direct you on how to structure your code.

Also, I suggest you open the file in binary mode, not text mode.

Todd

EDIT - nevermind - you already said you have a TEXT file.

Finally, you may want to decide whether you are reading 2014 or 1024 values from the file.

Also, if you know how many values there are, why are you doing this:

Code:

for (j=0; j<i-1;j++)

Which, by the way, will end up with one value less than the number in i - so if you read 1024 values, you will print only the first 1023 of them.


--
Mats

Check fscanf for success. It returns the number of items converted, so if both calls don't return 1, you've got an invalid file format.

Check whether fscanf succeeds:

Code:

	line_count = fscanf(file_ptr,"%x",&address[i]);
	line_count += fscanf(file_ptr,"%x",&value[i]);
	printf("Did I get two numbers this time? %s\n", line_count==2?"Yes":"No");

Note that once you get a non-hex value wedged into the input, all the remaining attempts at reading will fail on the same non-hex value -- so maybe check your input file too.

Originally Posted by Todd Burch

Also, I suggest you open the file in binary mode, not text mode.

Todd

Originally Posted by Original post

I have a text file containing hex values of the form...

Doesn't it make more sense to open it as a text-file if it's a text file? Opening files in binary mode should be the correct thing if the file is a non-text file.

--
Mats

Hohoho, my aren't we active today?

It is 2014 values i need to read, had been playing with a different file hecne the typo in the code sorry.

The file is of the following format:-

Code:

3A	1
2A	4
28	0
29	0
20	0
21	0
22	0
23	0
24	0
25	0
26	0
27	8F

so its 2 hex digits, 8 bits in each colum as a maxium. no row is empty.

cheers

hi,

tabstop and prelude, have tried your method. unfortunately the answer is NO each time,

thanks for the replies everyone

Hm. Well, that means that the very first thing in the file can't be converted to %x format, so that should be easy to find.