What the hell is going on??????????????????

[Jon Slaughter]

This has wasted about 4 hours of my time to narrow this stupid thing down
and I have no clue to why its screwing up. The problem is, I'm trying to
write a file and if I mess with the data array fwrite does not write the
exact size that I tell it to(even if I hard code it to write m bytes, it
write's n bytes)...

Heres example code that demonstrates the problem.... I'm using console under
VS.NET

#include <iostream>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

//using namespace std;

int Width()

{

return 640;

}

int Height()

{

return 480;

}

int Max_Color()

{

return 255;

}

int main(int argc, char *argv[])

{
unsigned char *Image3 = NULL;
printf("Allocating buffer...\n");

Image3 = new unsigned char[Width()*Height()];

if (Image3 == NULL) { printf("Cannot allocate memory!"); return 0; }

unsigned char max = 1;
printf("Doing loop...\n");

for(int j=0;j<Height();j++)

for(int i = 0;i<Width();i++)

{

// Here is the error, if I try to change the data, I get different file
sizes for the fwrite.... this makes no sense to me, as I would think that if
I tell fwrite to write m bytes, it should write m bytes(well, atleast not
more than m bytes)...

Image3[i+Width()*j] = i;

//Image3[i+Width()*j] = 0*i;
}


printf("Opening file...\n");

FILE *pgm = fopen("beta.tst","wt");

if (pgm == NULL) {printf("cannot write file"); return false; }

// Put pgm header

//fprintf(pgm, "P5\n#Test\n%d\n%d\n%d\n", Width(), Height(), Max_Color());

// Write data
printf("Writing Data...\n");

fwrite(Image3, 1, Width()*Height(), pgm);

/*

for(int j=0;j<Height();j++)

for(int i=0;i<Width();i++)

fputc(Get_Pixel(i,j), pgm);

*/
fclose(pgm);

printf("Press enter!");

char ch = getchar();

return true;

};

[Phlip]

Jon Slaughter wrote:

This has wasted about 4 hours of my time to narrow this stupid thing down
and I have no clue to why its screwing up. The problem is, I'm trying to
write a file and if I mess with the data array fwrite does not write the
exact size that I tell it to(even if I hard code it to write m bytes, it
write's n bytes)...

Heres example code that demonstrates the problem.... I'm using console under VS.NET

#include <iostream>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>
VS.NET and Outlook Express collude to screw up linefeeds.

You need to open Notepad, paste code into it, copy the code, and paste it
into Outlook Express.
//using namespace std; int Width()
{
return 640;
} int Height()
{
return 480;
}
Uh, making those static constants would be mostly harmless...
int Max_Color()
{
return 255;
}

int main(int argc, char *argv[])
{
unsigned char *Image3 = NULL;

printf("Allocating buffer...\n");

Image3 = new unsigned char[Width()*Height()];
Why not use vector?
if (Image3 == NULL) { printf("Cannot allocate memory!"); return 0; }
You need to read /Accelerated C++/, and not write "C-style C++". printf()
has different risks and benefits to std::cout, and 'new' throws an exception
if it fails.
// Here is the error, if I try to change the data, I get different file
sizes for the fwrite.... this makes no sense to me, as I would think that if I tell fwrite to write m bytes, it should write m bytes(well, atleast not
more than m bytes)... FILE *pgm = fopen("beta.tst","wt");
You opened the file for text, with a 't'.
fwrite(Image3, 1, Width()*Height(), pgm);

Remember when I said to copy your source into Notepad? fopen(...,"t") has a
related issue. Because MS (and IBM etc.) are superior to Unix, they end
linefeeds with \r\n. However, C and C++ come from Unix-land, where linefeeds
end with \n

The great thing about Standards is there are so many to choose from.

The tension between these utterly trivial conventions causes endless bugs
(mostly in MS-land). For example, Outlook Express inserted extra linefeeds
for no apparent reason when you pasted. The tension also causes bugs in C++
programs.

When you use fopen(...,"t"), you get "end-of-line text translation". Your
binary data contain a \x0A, which FILE translated into a \r\n, adding a
character.

You are waiting for me to stop pontificating and tell you the fix.
fopen(..., "wb") for binary.

--
Phlip
http://industrialxp.org/community/bi...UserInterfaces

[Mike Wahler]

"Jon Slaughter" <Jo***********@Hotmail.com> wrote in message
news:10*************@corp.supernews.com...

This has wasted about 4 hours of my time to narrow this stupid thing down
and I have no clue to why its screwing up. The problem is, I'm trying to
write a file and if I mess with the data array fwrite does not write the
exact size that I tell it to(even if I hard code it to write m bytes, it
write's n bytes)...
FILE *pgm = fopen("beta.tst","wt");

FILE *pgm = fopen("beta.tst","wb");

Read about 'text mode' and 'binary mode'.

-Mike