如何创建并运行 C 的 make 文件？

Question

我有3个文件

hellomain.c
hellofunc.c
helloheader.h

我正在通过 GCC 编译器运行。通常我会输入：

gcc helloheader.h hellomain.c hellofunc.c -o results

一切都会运行。

如何将其转换为 makefile？我知道我必须给它起个标题

makefile

。我知道我必须通过在编译器中输入

make

来调用它。但不确定在 makefile 中实际输入什么。

Answer 1

对于像您这样的项目来说，最简单的 makefile 可能是这样的：

# The name of the source files
SOURCES = hellomain.c hellofunc.c

# The name of the executable
EXE = results

# Flags for compilation (adding warnings are always good)
CFLAGS = -Wall

# Flags for linking (none for the moment)
LDFLAGS =

# Libraries to link with (none for the moment)
LIBS =

# Use the GCC frontend program when linking
LD = gcc

# This creates a list of object files from the source files
OBJECTS = $(SOURCES:%.c=%.o)

# The first target, this will be the default target if none is specified
# This target tells "make" to make the "all" target
default: all

# Having an "all" target is customary, so one could write "make all"
# It depends on the executable program
all: $(EXE)

# This will link the executable from the object files
$(EXE): $(OBJECTS)
    $(LD) $(LDFLAGS) $(OBJECTS) -o  $(EXE) $(LIBS)

# This is a target that will compiler all needed source files into object files
# We don't need to specify a command or any rules, "make" will handle it automatically
%.o: %.c

# Target to clean up after us
clean:
    -rm -f $(EXE)      # Remove the executable file
    -rm -f $(OBJECTS)  # Remove the object files

# Finally we need to tell "make" what source and header file each object file depends on
hellomain.o: hellomain.c helloheader.h
hellofunc.o: hellofunc.c helloheader.h

它可以更简单，但是有了这个你就有了一些灵活性。

---

为了完整起见，这可能是最简单的 makefile：

results: hellomain.c hellofunc.c helloheader.h
    $(CC) hellomain.c hellofunc.c -o results

这基本上就是您已经在命令行上执行的操作。它不是很灵活，如果任何文件发生变化，它会重建所有内容。

Answer 2

这是带有硬编码文件名的

makefile

。它很容易理解，但当您添加/删除源文件和头文件时，更新可能会很乏味。

results: hellomain.o hellofunc.o
    gcc $^ -o results

hellomain.o: hellomain.c helloheader.h
    gcc -c $<

hellofunc.o: hellofunc.c helloheader.h
    gcc -c $<

确保在 makefile 中使用制表符进行缩进。

Answer 3

SRC：https://makefiletutorial.com/

blah: blah.o
    cc blah.o -o blah # Runs third

blah.o: blah.c
    cc -c blah.c -o blah.o # Runs second

# Typically blah.c would already exist, but I want to limit any additional required files
blah.c:
    echo "int main() { return 0; }" > blah.c # Runs first

然后

$ make