what are the differences between = and := in a Makefile?

[meili100]

I have

OBJ = $(wildcard *.c)

and

OBJ := $(wildcard *.c)

Seems the effects are the same. What are their differences? I have seen many people adopt := ?!

[tabstop]

Have you read the manual? (As I recall, := means expand now, and = means expand later, but I might have that backwards.)

[meili100]

Yes, according to manual, you are right. But I did a test and it shows that

OBJ = $(wildcard *.c)

expends now.

Have you read the manual? (As I recall, := means expand now, and = means expand later, but I might have that backwards.)

[tabstop]

Did you look at the example on page 59 of the (gnu pdf) manual? Does that not work for you when you tested it?