The register keyword is still useful in compiler specific contexts. e.g., for GCC-ish compilers like gcc, clang:

    long result;
    register long nr __asm__("rax") = __NR_close;
    register long rfd __asm__("rdi") = fd;
    __asm__ volatile ("syscall\n" : "=a"(result) : "r"(rfd), "0"(nr) : "rcx", "r11", "memory", "cc");

The above is basically how you might implement the close(int) syscall on x86-64.

You don't need to be doing embedded programming to find it useful to dip down into assembly like that (though syscalls are perhaps a bad example, even for a syscall not provided by your C library -- that library probably provides a `syscall` function/macro that does all this in a platform agnostic way).

Also, "%.*" is extremely useful with strings, i.e., "%.*s". Your code base should be using length delimited strings (basically `struct S { int len; char* str; };`) throughout, in which case you can do `printf("%.*s\n", s.len, s.str);`