Makefile pattern rule fails?

Question

While using GNU-make, my Makefile has some pattern rule as:

%.o:%.c
    gcc $< -o:$@

This rule is added by me.

But when I do mak

Answer 1

If you put only this in a Makefile and call make:

%.o: %.cpp
  g++ -g -o $@ -c $<

It tells: make: *** No targets. Stop.

Because it's not a target. It's a rule.

It will work if your another target needs a .o file.

main.exe: main.o add.o
  g++ -g -o $@ $^

%.o: %.cpp
  g++ -g -o $@ -c $<