2个cpp程序的一个makefile

Question

您好，我需要为一个目录中的2个独立的cpp程序创建一个makefile。 我有此代码，但无法正常工作。 .o文件未创建。谢谢

OBJS = a b
EXEC = first_run second_run

#------ constant definitions

ALL_OBJ = $(OBJS:%=%.o)

all: $(EXEC)

clean:
    $(RM) $(EXEC) $(OBJS) $(ALL_OBJ); make all

CC = g++

DO_OBJS = $(CC) -cpp -o $@.o $@.cpp; touch $@
DO_EXEC = $(CC) -s -o $@ $(ALL_OBJ)

#------ now compile

$(OBJS):    $(@:%=%.o)
        $(DO_OBJS)

$(EXEC):    $(OBJS)
        $(DO_EXEC)

Answer 1

您的文件有两个问题，但是主要的问题似乎是您尝试将两个源文件都链接到一个可执行文件。 您必须列出每个程序及其依赖项。

改试试这个简单的Makefile：

SOURCES = a.cpp b.cpp
OBJECTS = $(SOURCES:%.cpp=%.o)
TARGETS = first_run second_run

LD = g++
CXX = g++
CXXFLAGS = -Wall

all: $(TARGETS)

# Special rule that tells `make` that the `clean` target isn't really
# a file that can be made
.PHONY: clean

clean:
    -rm -f $(OBJECTS)
    -rm -f $(TARGETS)

# The target `first_run` depends on the `a.o` object file
# It's this rule that links the first program
first_run: a.o
    $(LD) -o $@ $<

# The target `second_run` depends on the `b.o` object file
# It's this rule that links the second program
second_run: b.o
    $(LD) -o $@ $<

# Tells `make` that each file ending in `.o` depends on a similar
# named file but ending in `.cpp`
# It's this rule that makes the object files    
.o.cpp:

Answer 2

吻：

all: first_run second_run

clean:
    rm -f first_run second_run

first_run: a.c
    $(LINK.cc) $^ $(LOADLIBES) $(LDLIBS) -o $@

second_run: b.c
    $(LINK.cc) $^ $(LOADLIBES) $(LDLIBS) -o $@

Answer 3

我建议这个Makefile：

EXEC = first_run second_run
OBJS_FIRST = a.o
OBJS_SECOND = b.o

all: $(EXEC)

first_run: $(OBJS_FIRST)
    $(CXX) -o $@ $(OBJS_FIRST)

second_run: $(OBJS_SECOND)
    $(CXX) -o $@ $(OBJS_SECOND)

您无需定义对象构建，因为make已经知道如何执行该操作。