How to split a text file bit by bit into two files - c

Question

How can I split a text file into two other files bit by bit. I need all the even numbered bits in file A and all the odd ones in B. In other words, if File X is:
0101010111110000
Then File A would be: 00001100
and B would be: 11111100
Then I need to save those as .txt files. After that, I will need to merge them back together to get X again.
I am using c.
The code I have so far is as follows:
#include <stdio.h>
void printchar( unsigned char to_print )
{
unsigned char mask = 0x80;
for( int i = 0; i < 8; ++i )
{
if( (mask & to_print) > 0 )
{
printf( "%d", 1 );
}
else
{
printf( "%d", 0 );
}
mask = mask >> 1;
}
printf( "\n" );
}
void split( unsigned char * left, unsigned char * right, unsigned char input1, unsigned char input2 )
{
unsigned char mask = 0x80;
for( int i = 0; i < 4; ++i )
{
(*left) |= ( (input1 & mask) << i );
(*left) |= ( (input2 & mask) >> (4-i) );
mask = mask >> 1;
(*right) |= ( (input1 & mask) << (i+1) );
(*right) |= ( (input2 & mask) >> (3-i) );
mask = mask >> 1;
}
}
int main (int argc, const char * argv[])
{
unsigned char left = 0;
unsigned char right = 0;
unsigned char input1 = 0xA6;
unsigned char input2 = 0xB5;
split( &left, &right, input1, input2 );
printchar( left );
printchar( right );
return 0;
}

Answer 1

read char by char
in youre code build two buffer chars one with even and other with odd bits
to fully build 2 chars you need to read 2 chars from file
when you have read 4 chars from input file you can write 2 chars you have built
and so one
for part to same approach but in reverse.
You should be careful with the order of reading /writing even/odd bits