Justification

The use of non-standard output specifiers or non-standard flags is not portable.

Example

printf("%#i", i); /* WRONG */
printf("%Lo", i); /* WRONG */
printf("%#u", i); /* WRONG */
printf("%Lx", i); /* WRONG */
printf("%LX", i); /* WRONG */
printf("%hf", f); /* WRONG */
printf("%he", f); /* WRONG */
printf("%hE", f); /* WRONG */
printf("%hg", d); /* WRONG */
printf("%hG", d); /* WRONG */
printf("%#c", c); /* WRONG */
printf("%#%"); /* WRONG */
printf("%#s", p); /* WRONG */
printf("%#n", p); /* WRONG */
printf("%#p", v); /* WRONG */
fprintf(stderr, "error occurred: %m\n”); /* WRONG */