print-all.o is a so called C object file. It is the result of partial compilation of the instructor's print-all.c program. The printall executable is print-all.c compiled together with the instructor's version of all Lab 4 functions.
print-all.o was compiled without adding grove.c code. Thus, it is not a complete executable. But you can compile it together with your grove.c file to create an executable that will print all your code. The compilation command is
$ gcc -ansi -Wall -Werror -lm -o myPrintall print-all.o grove.c
To compare the results of your work to the instructor's results you can do this:
$ chmod u+x printall $ ./printall > alex-output $ ./myPrintall > my-output $ diff my-output alex-outputIf the last command produces NO visible output, your code produces exactly the same output as the instructor's code.