Show me the steps to solve Now, complete the code for the write$\_$data function. You can write your code in the same box above where I left the function stub $($the return $0$ in the write$\_$data function$).$ You will need to look up and learn how to use the fwrite$()$ function.

This function is given a filename, a number specifying the number of bytes to write, and a string of bytes. Why must we pass the number of bytes as a parameter? Why can't we simply find out the length from the string? Well, C doesn't have strings. What we have is a char$*,$ which is the address where the "string" starts. We can't ask the address how long it is $-$ it is just an address!

Modify the main function above so that it reads a file's contents into memory and then writes out a new file with the contents. Ensure that the two files are exactly the same $-$ byte for byte. To do this, you may want to check the size of the files, or use the hexdump command. This command will print out the contents of a file in hex. For instance:

$0000000048656$c $6$c $6$f $20776$f $726$c $642120204920|$Hello world! I $|$

$000000106$c $6$f $766520636$f $6$d $7075746572732$e $0$a $|$love computers..$|$

$00000020$

$\%\%$writefile file$\_$tools.c

#include "file$\_$tools.h$"$

#include

size$\_$t read$\_$data$($char$*$ filename, unsigned char$**$ data$)\{$

$//$ When we open a file, we keep that location

$//$ as a file pointer, so declare one.

FILE$*$ fp;

$//$ Open the file for reading.

fp $=$ fopen$($filename$,"$r$")$;

$//$ Go to the end of the file.

fseek$($fp$,0$L$,$ SEEK$\_$END$)$;

$//$ ftell says where we are in the file. Since we went to the

$//$ end, this will tell us how many bytes are in the file.

size$\_$t file$\_$size $=$ ftell$($fp$)$;

$//$ Go back to the beginning.

fseek$($fp$,0$L$,$ SEEK$\_$SET$)$;

$//$ Now, we know how many bytes we need. Ask for that much space,

$//$ and store the address.

$*$data $=$ malloc$($file$\_$size$)$;

$//$ Read the data and store it in our location.

fread$(*$data$,1,$ file$\_$size, fp$)$;

$//$ Close the file.

fclose$($fp$)$;

$//$ Return the number of bytes we found.

return file$\_$size;

$\}$

size$\_$t write$\_$data$($char$*$ filename, size$\_$t data$\_$size, unsigned char$*$ data$)\{$

return $0$;

$\}$

$\%\%$writefile reversal.c

#include

#include

#include "file$\_$tools.h$"$

int main$($int argc, char$**$ argv$)\{$

$//$ Create a variable that will hold the address of where

$//$ our data is loaded into.

unsigned char$*$ data;

$//$ Load the data into that area and get back the number of

$//$ bytes read.

size$\_$t file$\_$size $=$ read$\_$data$("./$shared$/$audio$/$backwards$.$wav", &data$)$;

printf$("$Size: $\%$lu bytes.

$",$ file$\_$size$)$;

printf$("$

$")$;

return $0$;

$\}$