在 SRCEXTS 中指定程序中使用的文件类型。C/C++ 程序的扩展名一般有比较固定的几种形式:.c、.C、.cc、.cpp、.CPP、.c++、.cp、或者.cxx(参见 man gcc)。扩展名决定了程序是 C 还是 C++ 程序:.c 是 C 程序,其它扩展名表示 C++ 程序。一般固定使用其中的一种扩展名即可。但是也有可能需要使用多种扩展名,这可以在 SOURCE_EXT 中一一指定,各个扩展名之间用空格分隔。
虽然并不常用,但是 C 程序也可以被作为 C++ 程序编译。这可以通过在 Makefile 中设置 CC = $(CXX) 和 CFLAGS = $(CXXFLAGS) 两项即可实现。
这个 Makefile 支持 C、C++ 以及 C/C++ 混合三种编译方式:
如果只指定 .c 扩展名,那么这是一个 C 程序,用 $(CC) 表示的编译命令进行编译和连接。
如果指定的是除 .c 之外的其它扩展名(如 .cc、.cpp、.cxx 等),那么这是一个 C++ 程序,用 $(CXX) 进行编译和连接。
如果既指定了 .c,又指定了其它 C++ 扩展名,那么这是 C/C++ 混合程序,将用 $(CC) 编译其中的 C 程序,用 $(CXX) 编译其中的 C++ 程序,最后再用 $(CXX) 连接程序。
这些工作都是 make 根据在 Makefile 中提供的程序文件类型(扩展名)自动判断进行的,不需要用户干预。
############################################################################### # # Generic Makefile for C/C++ Program # # Author: whyglinux (whyglinux AT hotmail DOT com) # Date: 2006/03/04
# Description: # The makefile searches in directories for the source files # with extensions specified in , then compiles the sources # and finally produces the , the executable file, by linking # the objectives.
# Usage: # $ make compile and link the program. # $ make objs compile only (no linking. Rarely used). # $ make clean clean the objectives and dependencies. # $ make cleanall clean the objectives, dependencies and executable. # $ make rebuild rebuild the program. The same as make clean && make all. #==============================================================================
## Customizing Section: adjust the following if necessary. ##=============================================================================
# The executable file name. # It must be specified. # PROGRAM := a.out # the executable name PROGRAM :=
# The directories in which source files reside. # At least one path should be specified. # SRCDIRS := . # current directory SRCDIRS :=
# The source file types (headers excluded). # At least one type should be specified. # The valid suffixes are among of .c, .C, .cc, .cpp, .CPP, .c++, .cp, or .cxx. # SRCEXTS := .c # C program # SRCEXTS := .cpp # C++ program # SRCEXTS := .c .cpp # C/C++ program SRCEXTS :=
# The flags used by the cpp (man cpp for more). # CPPFLAGS := -Wall -Werror # show all warnings and take them as errors CPPFLAGS :=
# The compiling flags used only for C. # If it is a C++ program, no need to set these flags. # If it is a C and C++ merging program, set these flags for the C parts. CFLAGS := CFLAGS +=
# The compiling flags used only for C++. # If it is a C program, no need to set these flags. # If it is a C and C++ merging program, set these flags for the C++ parts. CXXFLAGS := CXXFLAGS +=
# The library and the link options ( C and C++ common). LDFLAGS := LDFLAGS +=
## Implict Section: change the following only when necessary. ##============================================================================= # The C program compiler. Uncomment it to specify yours explicitly. #CC = gcc
# The C++ program compiler. Uncomment it to specify yours explicitly. #CXX = g++
# Uncomment the 2 lines to compile C programs as C++ ones. #CC = $(CXX) #CFLAGS = $(CXXFLAGS)
# The command used to delete file. #RM = rm -f
## Stable Section: usually no need to be changed. But you can add more. ##============================================================================= SHELL = /bin/sh SOURCES = $(foreach d,$(SRCDIRS),$(wildcard $(addprefix $(d)/*,$(SRCEXTS)))) OBJS = $(foreach x,$(SRCEXTS), $(patsubst %$(x),%.o,$(filter %$(x),$(SOURCES)))) DEPS = $(patsubst %.o,%.d,$(OBJS))
.PHONY : all objs clean cleanall rebuild
all : $(PROGRAM)
# Rules for creating the dependency files (.d). #--------------------------------------------------- %.d : %.c @$(CC) -MM -MD $(CFLAGS) $<
%.d : %.C @$(CC) -MM -MD $(CXXFLAGS) $<
%.d : %.cc @$(CC) -MM -MD $(CXXFLAGS) $<
%.d : %.cpp @$(CC) -MM -MD $(CXXFLAGS) $<
%.d : %.CPP @$(CC) -MM -MD $(CXXFLAGS) $<
%.d : %.c++ @$(CC) -MM -MD $(CXXFLAGS) $<
%.d : %.cp @$(CC) -MM -MD $(CXXFLAGS) $<
%.d : %.cxx @$(CC) -MM -MD $(CXXFLAGS) $<
# Rules for producing the objects. #--------------------------------------------------- objs : $(OBJS)
%.o : %.c $(CC) -c $(CPPFLAGS) $(CFLAGS) $<
%.o : %.C $(CXX) -c $(CPPFLAGS) $(CXXFLAGS) $<
%.o : %.cc $(CXX) -c $(CPPFLAGS) $(CXXFLAGS) $<
%.o : %.cpp $(CXX) -c $(CPPFLAGS) $(CXXFLAGS) $<
%.o : %.CPP $(CXX) -c $(CPPFLAGS) $(CXXFLAGS) $<
%.o : %.c++ $(CXX -c $(CPPFLAGS) $(CXXFLAGS) $<
%.o : %.cp $(CXX) -c $(CPPFLAGS) $(CXXFLAGS) $<
%.o : %.cxx $(CXX) -c $(CPPFLAGS) $(CXXFLAGS) $<
# Rules for producing the executable. #---------------------------------------------- $(PROGRAM) : $(OBJS) ifeq ($(strip $(SRCEXTS)), .c) # C file $(CC) -o $(PROGRAM) $(OBJS) $(LDFLAGS) else # C++ file $(CXX) -o $(PROGRAM) $(OBJS) $(LDFLAGS) endif
-include $(DEPS)
rebuild: clean all
clean : @$(RM) *.o *.d
cleanall: clean @$(RM) $(PROGRAM) $(PROGRAM).exe
### End of the Makefile ## Suggestions are welcome ## All rights reserved ### ###############################################################################
下面提供两个例子来具体说明上面 Makefile 的用法。
例一 Hello World 程序
这个程序的功能是输出 Hello, world! 这样一行文字。由 hello.h、hello.c、main.cxx 三个文件组成。前两个文件是 C 程序,后一个是 C++ 程序,因此这是一个 C 和 C++ 混编程序。