Linker returns “relocation has an invalid symbol at symbol index…”

Question

I am trying out some code on Ubuntu. I\'m trying to run the following code

#include 
#include 

        

Answer 1

Interestingly, I get the same error if I try to compile a .h file instead of a .c file, and link against a library, all in one step.

Here is a greatly reduced example:

$ echo 'int main () {}' > test.h
$ g++ test.h -ltommath && echo success
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status

In this case, the solution is to rename the file to end with .c:

$ echo 'int main () {}' > test.c
$ g++ test.c -ltommath && echo success
success