Thread: Huge string manipulation problem.

OK, I have a big problem, I don't know why this is happening to me. I'm trying to output a huge hex string to a FILE, but its not working for some reason it just gives me this in output.txt == ( MZ ) ??????

Code:

#include<stdio.h>
#include<string.h>
#include<stdlib.h>

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



unsigned char rawData[401408] = {
	0x4D, 0x5A, 0x90, 0x00, 0x03, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
	0xFF, 0xFF, 0x00, 0x00, 0xB8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
	0xF8, 0x00, 0x00, 0x00, 0x0E, 0x1F, 0xBA, 0x0E, 0x00, 0xB4, 0x09, 0xCD,
	0x21, 0xB8, 0x01, 0x4C, 0xCD, 0x21, 0x54, 0x68, 0x69, 0x73, 0x20, 0x70,
	0x72, 0x6F, 0x67, 0x72, 0x61, 0x6D, 0x20, 0x63, 0x61, 0x6E, 0x6E, 0x6F,
	0x74, 0x20, 0x62, 0x65, 0x20, 0x72, 0x75, 0x6E, 0x20, 0x69, 0x6E, 0x20,
	0x44, 0x4F, 0x53, 0x20, 0x6D, 0x6F, 0x64, 0x65, 0x2E, 0x0D, 0x0D, 0x0A,
	0x24, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xF9, 0xD2, 0x19, 0xBE,
	0xBD, 0xB3, 0x77, 0xED, 0xBD, 0xB3, 0x77, 0xED, 0xBD, 0xB3, 0x77, 0xED,
	0xAE, 0xBB, 0x1E, 0xED, 0xB0, 0xB3, 0x77, 0xED, 0xB8, 0xBF, 0x17, 0xED,
	0xBF, 0xB3, 0x77   /* it is to huge to put all the HEX  on this post,  its [401408] elements long   };    */



  	FILE* Binary_1 = fopen("output.txt","w");

  	fprintf(Binary_1,"%s",string1);

  	fclose(Binary_1);


return(0);
}

output.txt = ( MZ )










But when i try a smaller peace of string of Hex, it outputs correctly.

Code:

#include<stdio.h>
#include<string.h>
#include<stdlib.h>

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

char string1[5] = { 0x68, 0x65, 0x6C, 0x6C, 0x6F };

  	FILE* Binary_1 = fopen("output.txt","w");

  	fprintf(Binary_1,"%s",string1);

  	fclose(Binary_1);


return(0);
}

output.txt = ( hello )







I don't know what could be the problem, could someone help me out. Does string creation have a SIZE limit or something.

If you are going to handle your char's as a string - using %s for the print format, etc., you should add an end of string char, to the end of the string, as well: '\0'.

But your first problem is you've gone way over the limit for the stack, and need to use dynamic memory, as mentioned above.

Or try to use UNICODE representation instead of ANSI
ANSI:
char string1[5]
UNICODE:
char wstring1[5]
when representing data using UNICODE add L before the string

Originally Posted by anne03

Or try to use UNICODE representation instead of ANSI
ANSI:
char string1[5]
UNICODE:
char wstring1[5]
when representing data using UNICODE add L before the string

What does it change regarding the allocable stack memory?

Have you tried to declare it as static?

Isn't a binary file starting with MZ an executable? What exactly are you doing here? I sort of smell something bad.

Yeah, how interesting is the Google search for that file size?

Thanks for all the replies and yes it's a binary file ill try this with malloc() and see if it works

Originally Posted by zalezog

Actually, since OP used %s , the hex unsigned chars were interpreted as normal chars and written to the output stream where
0x4D = 'M',
0x5A = 'Z',
0x90 = it did print if you look closely, but actually may not be a printable character. ( so it seems to be a space )

The example program, which jadaces says prints it correctly may not have produced the desired result, since you wrote to file, you possibly missed 'something'.Try your own program using stdout.

Code:

#include<stdio.h>
#include<string.h>
#include<stdlib.h>

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

char string1[5] = { 0x68, 0x65, 0x6C, 0x6C, 0x6F };

  	FILE* Binary_1 = stdout;

  	fprintf(Binary_1,"%s",string1);

  	


return(0);
}

Finally, could you post an example of how the output file should be without printing implementation specific chars.

It should output to a .exe file and able to execute like normal.

Originally Posted by laserlight

jadaces, how do you explain rags_to_riches' observation?

Well am trying to incorporate wget.exe, it's exactly that about of bytes. Whats so wrong with trying to do that.