rdmNumGen error

g++   -c /Users/brandonobriant/CS161_C++/week5/Projects/rndGen.cpp -o /Users/brandonobriant/CS161_C++/week5/Projects/rndGen.o
g++  -o /Users/brandonobriant/CS161_C++/week5/Projects/rndGen /Users/brandonobriant/CS161_C++/week5/Projects/rndGen.o
Undefined symbols for architecture x86_64:
  "rand_int(int const&, int const&, int&)", referenced from:
      _main in rndGen.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Process terminated with status 1 (0 minute(s), 0 second(s))
0 error(s), 0 warning(s) (0 minute(s), 0 second(s))