Using VLFeat from C

Question

I am trying to use VLFeat in my C code on Ubuntu 16.04.3. Following the official instructions, I created a test file:

extern "C"
{
#include <vlfeat/vl/svm.h>
}

int main (int argc, const char * argv[]) {
  VL_PRINT ("Hello world!") ;
  return 0;
}

From the command line, I can confirm that svm.h is in vlfeat/vl. I then try

gcc main.cpp

but get the error message

main.cpp:3:27: fatal error: vlfeat/vl/svm.h: No such file or directory

Any advice on how to correctly use VLFeat in C code? Thanks.