convert binary file to txt file

[xiao]

Can I fullfill this task? Using fred and fwrite?

[Barry Schwarz]

On Wed, 23 Jul 2008 19:40:54 +0000, Richard Heathfield
<rj*@see.sig.in validwrote:

>xiao said:

<snip>

> Here is my program: I just want to converted the input file to see
the content of it. But seems something wrong with opnning the file.

I'll give you six.

>#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#define MAX_PATH_LENGTH 100000000

/* Define the data structure for the file header information */
typedef struct
{
short num;

} HEADER;

typedef struct
{

short x;

} DATA;

int main(void)
{

short xx,numn;
char disp[MAX_PATH_LENGTH];

1) You're asking for an object 100,000,000 bytes in size. C only guarantees
you an object 32,767 bytes in size (65,535 if you have a C99
implementation , which you probably don't).

>int i;
FILE *in, *out;
HEADER nscrdh;
DATA nscrd;

/* Determine the file names to be read from and written to */

/* Open the files to be read from and written to*/
in = fopen("CldTotal Stats_8.dat","r ");

2) You don't check that this call succeeded. If it fails, the behaviour of
your program is undefined.

3) If you wanted to open this file in binary mode, you should specify "rb"
as the mode, not just "r".

>out = fopen("newstats .txt","wt");

4) You don't check that this call succeeded. If it fails, the behaviour of
your program is undefined.

5) The fopen function has no "wt" mode. If you mean you want a text file,
specify "w".

>>
/* Read necessary header data into local variables & confirm file
format */
for (i=0; i<84; i++)
{
fread(&nscrdh, sizeof(short),1 ,in);

6) Here, you show confusion about whether you're reading a HEADER (you're
passing a pointer to a HEADER object) or a short (you use sizeof(short) in
the call). Clearer: fread(&nscrdh, sizeof nscrdh, 1, in);

In this case, using sizeof nscrdh can cause data to be skipped if the
compiler was perverse enough to put padding after the last (only)
member of the structure.

To me the real question is why bother with a struct if you only have
one scalar member?
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[Barry Schwarz]

On Wed, 23 Jul 2008 12:32:55 -0700 (PDT), xiao <li*********@gm ail.com>
wrote:

snip

Here is my program: I just want to converted the input file to see
the content of it. But seems something wrong with opnning the file.
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#define MAX_PATH_LENGTH 100000000

/* Define the data structure for the file header information */
typedef struct
{
short num;

} HEADER;

typedef struct
{

short x;

} DATA;

int main(void)
{

short xx,numn;
char disp[MAX_PATH_LENGTH];
int i;
FILE *in, *out;
HEADER nscrdh;
DATA nscrd;

/* Determine the file names to be read from and written to */

/* Open the files to be read from and written to*/
in = fopen("CldTotal Stats_8.dat","r ");
out = fopen("newstats .txt","wt");

/* Read necessary header data into local variables & confirm file
format */
for (i=0; i<84; i++)
{
fread(&nscrdh, sizeof(short),1 ,in);

Does the header contain 84 shorts or 84 char?

numn=nscrdh.num ;

Why not read directly in numn?

sprintf(disp, "%d \n", numn);

Here you almost invoke undefined behavior. %d expects an int; you are
attempting to pass a short. Fortunately, for a variadic function, an
"unspecifie d" short will be promoted to int. Did you really plan on
this or were you just lucky?

Do you really intend to memorize the binary representation of at least
65,536 different possible short values. Most people try to decode
binary data in 8 bit chunks which only requires memorizing 256
representations .

In either case, wouldn't it be easier to print the data in hex?

>/* Write header, ray information into output file */
fputs(disp, out);
}
for (i=0; i <8960000; i++)

Are you sure your file contains this much data.

{
fread(&nscrd,1, sizeof(short),i n);
xx= nscrd.x;
sprintf(disp, "%d \n", xx);
fputs(disp, out);
}
fclose(in);
fclose(out);

return 0;
}

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[Barry Schwarz]

On Wed, 23 Jul 2008 18:10:41 -0700 (PDT), xiao <li*********@gm ail.com>
wrote:

snip 44 lines of obsolete discussion

>haha .thank you~ i changed my mind here , If I define it like this:

short xx[800][800];
or
typedef struct
{
short x[800][800];
} NSC_RAY_DATA
how can I access the data in fread and fprintf?
I tried this:

fread(xx,sizeof (xx),14,in);

What is the size of xx? Literally, how many bytes does it occupy? How
many objects of that size did you define? How many did you request
fread to process? What happens when you try to read more data than
your buffer will hold?

for(i=0; i<14 ;i++)
{ fprintf(out,"%h d", xx[i]);}

What is the type of the expression xx[i]? What happens automatically
to expressions of this type when they are used in expressions where
they are evaluated? What is the type of the expression fprintf
receives? What type of expression did %hd promise fprintf? What
happens when you lie to fprint like this (hint - same as above)?

>
and
fread(&nscrd,si zeof(nscrd),14, in);

You introduced a new structure but never told us what nscrd is. Is it
the same as in your earlier post? If so, you have exactly the same
problem here as you do in the fread call using xx.

for(a=0; a<800 ;a++){
for(b=0; b<800 ;b++){
xx[a][b]=nscrd.x[a][b];

Nowhere in any of your code was nscrd.x an array. It was always a
short.

}
}
fprintf(out,"%h d", xx);

This fprintf call has the same problem as the one above.

>

And both of them remind me that :

warning: int format, pointer arg (arg 3)

As well they should. What type does %hd promise to provide? What
type do you actually provide? Are the two in any way compatible?
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