c - Implementation of printf -

can please explain me implementation of printf prints string correctly?

version 1:

printf(const char * s) {      while(*s != '\0') {           write(s, 1, f);           s++;      } } 

version 2:

printf(const char *s) {      write(s, strlen(s), f); } 

both print "a string correctly". print given string in argument correctly.

if question better implementation suggest depends on implementation of write.

option 1 slower if write call has large enough overhead or can buffer characters before committing write.

option 2 slower if write unoptimized. example puts character character on serial connection. here pay additional iteration of string strlen.

note write call takes file descriptor first argument, not last.