You just can''t compile multiple targets with one invocation of gcc that way. You might be able to hack it using ''xargs'' (this is a unix thing and I don''t know enough about it to really help), but I think what you really need is something more like:

PROGS = frequencies huffman encode
OBJS = frequencies.o huffman.o encode.o
all: $(PROGS)
frequencies: frequencies.o
g++ -o frequencies frequencies.o
frequencies.o: frequencies.cpp
g++ -c frequencies.cpp
huffman: huffman.o
g++ -o huffman huffman.o
huffman.o: huffman.cpp
g++ -c huffman.cpp
encode: encode.o
g++ -o encode encode.o
encode.o: encode.cpp
g++ -c encode.cpp
clean:
rm -f $(PROGS) $(OBJS)

(I can''t type tabs apparently. But you know where they go )

Basically, I made a target for each individual app, and set up "all" recursively to build those targets.