What does the compiler error “missing binary operator before token” mean?

Question

I recently got the following error when trying to compile with gcc:

error: missing binary operator before token \"(\"

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Answer 1

If you are on Linux, make sure that you do not have a header named features.h inside your project files. I had one with this name, which resulted in:

/usr/include/x86_64-linux-gnu/bits/huge_val.h:25: error: function pointer expected

or

/usr/include/bits/huge_val.h:26:18: error: missing binary operator before token "("

That is because some system headers like huge_val.h use macros like __GNUC_PREREQ that are defined by /usr/include/features.h (learn more about this header in this SO question).

In my case I first saw this error when I started to use gcc's -I option which suddenly made gcc select my project include directory before the default system include directories.