- Inference rules
- Inference rule = a generalized rule that can be applied to a group of files with similar file names
- Special notations
used to formulate inference rules:
% = wildcard character - match 0 or more characters $< = first item in the list of dependent filenames $^ = all items in the list of dependent filenames $@ = current target name including the extension $* = current target name not including the extension
Summary: main.o: file1.o file2.o file3.o ---- ------- $* $< ====== ========================= $@ $^
- Example: inference rule
%.o: %.c func5b.h gcc -c $<Meaning:
- The character % is
the wildcard character
% matches 0 or more characters in a file name
- Any file
with name "*.o" depends
on a file with same prefix but ends
in
".c" (and also on
the header file
func5b.h)
Example:
%.o: %c func5b.h gcc -c $< Will generate all these dependencies: file1.o: file1.c func5b.h gcc -c file1.c file2.o: file2.c func5b.h gcc -c file2.c file3.o: file3.c func5b.h gcc -c file3.c .... anyFilename.o: sameFileName.c func5b.h gcc -c sameFileName.c
- The character % is
the wildcard character
- Previously, we used the following
Makefile:
main: func5a.o func5b.o gcc -o main func5a.o func5b.o func5a.o: func5a.c func5b.h gcc -c func5a.c func5b.o: func5b.c func5b.h gcc -c func5b.c
- We can replace the
last 2 rules with
one inference rule:
main: func5a.o func5b.o gcc -o main func5a.o func5b.o %.o: %.c func5b.h gcc -c $<
- Note: this Makefile is even better
main: func5a.o func5b.o gcc -o $@ $^ # $@ = current target name including the extension (= main) # $^ = all items in the list of dependent filenames (= func5a.o func5b.o) %.o: %.c func5b.h gcc -c $<
- Example Program:
(Demo above code)
- The func5a.c Prog file: click here
- The func5b.c Prog file: click here
- The func5b.h header file: click here
- The Makefile: click here
How to run the program:
- Right click on link and
save in a scratch directory
- To compile: make
- To run: main