Sometimes fixing a bit twiddling or other low level bug comes down to showing the individual bits. printf does not support printing an integer in radix 2, despite originating from times when code was closer to the metal. The code in reprint is as follows:

/* Print 42 as binary */
reprintf("\f&r", 42);

/* Print 42 as hex */
reprintf("\f$r", 42);

/* Print 42 as octal */
reprintf("\f%r", 42);

These use of '$', '%', and '&' are not entirely arbitrary, as the three characters are sequential in value:

1. '$' is 0x24 and selects hexadecimal
2. '%' is 0x25 and selects octal
3. '&' is 0x26 and selects radix 2 (binary)
4. Default output is in decimal