Does Posix supply format string macros for printf/scanf?

Question

The printf and scanf families of functions in C consume a handful of primitive format specifiers that correspond to the fundamental data types –

Answer 1

The sfio package (part of AT&T Labs' open source AST software) has functions analogous to printf and scanf which let you specify the size of the numeric value (typically using sizeof()) as an additional parameter. Some examples:

sfprintf(sfstdout, "%I*d", sizeof(intval), intval);
sfscanf(sfstdin, "%I*f", sizeof(fltval), &fltval);

USENIX paper: Extended Data Formatting Using Sfio .

Answer 2

Posix guarantees that sys/types.h values are an "arithmetic type of appropriate length" with a few others as being further specified as unsigned or signed 'extended length'. The only standards-acceptable way to output those would be to transfer it via cast in the largest appropriate language type (u)intmax_t and then output that.

Inputting them would be more dangerous (i.e., not possible in a standards-compliant fashion) as it would be difficult to guarantee your conversion to the base type didn't overflow something.