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Makefile Utility SinhVienZone.com https://fb.com/sinhvienzonevn Motivation  Small program  Single file  “Not so small” programs  Many lines of code  Multiple components  More than one programmer SinhVienZone.com https://fb.com/sinhvienzonevn Faculty of Computer Science and Engineering - HCMUT Motivation (cont.)  Problems  Long files are harder to manage (for both programmers and machines)  Every change requires long compilation  Many programmers can not modify the same file simultaneously Division to components is desired SinhVienZone.com https://fb.com/sinhvienzonevn Faculty of Computer Science and Engineering - HCMUT Program Compiling  Manual  Efforts  Shell script  Time  Makefile  Convenient  Compiling time SinhVienZone.com https://fb.com/sinhvienzonevn Faculty of Computer Science and Engineering - HCMUT Makefile  Text file  make  *NIX systems  Build, install, and uninstall programs  Avoid re-building targets which are up-to-date  Not limited to C/C++ programs SinhVienZone.com https://fb.com/sinhvienzonevn Faculty of Computer Science and Engineering - HCMUT Example Project: main.c, sum.c, sum.h sum.h is included in main.c & sum.c executable file: sum SinhVienZone.com https://fb.com/sinhvienzonevn Faculty of Computer Science and Engineering - HCMUT Example (cont.)  Compile $ gcc –o sum main.c sum.c or $ gcc –c main.c $ gcc –c sum.c $ gcc –o sum main.o sum.o => What happens if file main.c is modified SinhVienZone.com https://fb.com/sinhvienzonevn Faculty of Computer Science and Engineering - HCMUT Project Structure sum sum.o sum.c SinhVienZone.com main.o sum.h main.c https://fb.com/sinhvienzonevn Faculty of Computer Science and Engineering - HCMUT Makefile content # This is an example of Makefile CC=gcc sum: main.o sum.o $(CC) –o sum main.o sum.o main.o: main.c sum.h $(CC) –c main.c sum.o: sum.c sum.h Rule $(CC) –c sum.c TAB Target Dependency SinhVienZone.com Action https://fb.com/sinhvienzonevn Faculty of Computer Science and Engineering - HCMUT Built-in Macros sum: main.o sum.o gcc –o $@ $^ c.o: gcc –c $< main.o sum.o: sum.h gcc –c $*.c SinhVienZone.com https://fb.com/sinhvienzonevn Faculty of Computer Science and Engineering - HCMUT 10 Built-in Macros (cont.) $@ - The name of the target of the rule $< - The name of the first dependency $^ - The names of all the dependencies $? - The names of all dependencies that are newer than the target $* - The name of the target of the rule without extension SinhVienZone.com https://fb.com/sinhvienzonevn Faculty of Computer Science and Engineering - HCMUT 11 Make Operation  Project dependencies tree is constructed  Target of first rule should be created  We go down the tree to see if there is a target that should be recreated This is the case when the target file is older than one of its dependencies  In this case we recreate the target file according to the action specified, on our way up the tree Consequently, more files may need to be recreated  If something is changed, linking is usually necessary SinhVienZone.com https://fb.com/sinhvienzonevn Faculty of Computer Science and Engineering - HCMUT 12 Make Operation (cont.) File sum main.o sum.o main.c sum.c sum.h SinhVienZone.com Last Modified 10:03 09:56 09:35 10:45 09:14 08:39 https://fb.com/sinhvienzonevn Faculty of Computer Science and Engineering - HCMUT 13 Make Operation (cont.) sum sum.o 9:35 sum.c 9:14 SinhVienZone.com 10:03 main.o 9:56 sum.h 8:39 main.c 10:45 https://fb.com/sinhvienzonevn Faculty of Computer Science and Engineering - HCMUT 14 Make Operation (cont.)  Operations performed: gcc –c main.c gcc –o sum main.o sum.o  main.o should be recompiled (main.c is newer)  Consequently, main.o is newer than sum and therefore sum should be recreated (by re-linking) SinhVienZone.com https://fb.com/sinhvienzonevn Faculty of Computer Science and Engineering - HCMUT 15 Questions??? SinhVienZone.com https://fb.com/sinhvienzonevn ... 10: 03 09:56 09 :35 10:45 09:14 08 :39 https://fb.com/sinhvienzonevn Faculty of Computer Science and Engineering - HCMUT 13 Make Operation (cont.) sum sum.o 9 :35 sum.c 9:14 SinhVienZone.com 10: 03. .. first dependency $^ - The names of all the dependencies $? - The names of all dependencies that are newer than the target $* - The name of the target of the rule without extension SinhVienZone.com... Rule $(CC) –c sum.c TAB Target Dependency SinhVienZone.com Action https://fb.com/sinhvienzonevn Faculty of Computer Science and Engineering - HCMUT Built-in Macros sum: main.o sum.o gcc –o $@ $^