#include <stdio.h>
 
char buffer[9] = {};
 
char* atob(char ch, char *buffer) {
  // Check for lowercase alphabets (a-z) and valid buffer
  if (ch < 'a' || ch > 'z') {
    return NULL; // Indicate error
  }
 
  // Convert ASCII value to binary
  int ascii_value = ch;
  int i;
 
  // Build the binary string in the provided buffer (reverse order)
  for (i = 0; i < 8; i++) {
    buffer[i] = (ascii_value & (1 << (7 - i))) ? '1' : '0';
  }
 
  // Add null terminator at the end (overwrite buffer[8] if provided)
  buffer[8] = '\0';
 
  return buffer;
}
 
int main(void) {
	printf("%c -> atob -> %s", 'd', atob('d',&buffer));
	return 0;
}
 

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