Question

I can link my example.o using this command with no problem

gcc example.o -o example.exe

but if I manually link it using ld, I get many errors:

ld example.o -o example.exe
example.o:example.c:(.text+0x1d7e5): undefined reference to `strcmp'
example.o:example.c:(.text+0x1d9b6): undefined reference to `_ftime'
example.o:example.c:(.text+0x1dcbd): undefined reference to `strchr'
example.o:example.c:(.text+0x1df7f): undefined reference to `strtoul'
...

How does gcc invoke the linker and link the object file into an executable?

Answer 1

The answer is more complex than you imagine.

Run

gcc -v example.o -o example.exe

to understand what is happening

The gory details are operating system specific. On Linux, it silently loads crt*.o objects (containing the _start assembly code calling your main etc etc…) and the C library. I have no idea of what your platform is doing; I never compiled on Windows.