Makefile的致命错误：无法创建OBJ / calc.o [英] Makefile Fatal error: can't create obj/calc.o

问题描述

我试图做一个makefile一个简单的计算器为大专以上项目。我需要它做的，我在网​​上搜索了教程和我最终发现了这个code：

I'm trying to make a makefile for a simple calculator for a college project. I need it done, and I've searched the web for tutorials and I eventually found this code:

IDIR =include
CC=gcc
CFLAGS=-I$(IDIR)

ODIR=obj
LDIR=lib
SDIR=src

LIBS=-lm

_DEPS = calc.h
DEPS = $(patsubst %,$(IDIR)/%,$(_DEPS))

_OBJ = calc.o libcalc.o 
OBJ = $(patsubst %,$(ODIR)/%,$(_OBJ))


$(ODIR)/%.o: $(SDIR)/%.c $(DEPS)
    $(CC) -c -o $@ $< $(CFLAGS)

calc: $(OBJ)
    gcc -o $@ $^ $(CFLAGS) $(LIBS)

.PHONY: clean

clean:
    rm -f $(ODIR)/*.o *~ core $(INCDIR)/*~ 

make命令的输出是

The output of the make command is

gcc -c -o obj/calc.o calc.c -I../include
Assembler messages:
Fatal error: can't create obj/calc.o: No such file or directory
make: *** [obj/calc.o] Error 1

我的教授给了我们不含铅，也没有说明这一点，所以我真的失去了。

My professor gave us no lead nor instruction to this, so I'm really lost.

我的项目分为三个文件夹： LIB ，的src 和包含。 的src 包含项目，命名为 calc.c ，包括源包含名为标题 calc.h 和 LIB 包含名为库 libcalc .C 。

My project is divided in three folders: lib, src and include. src contains the source for the project, named calc.c, include contains the header named calc.h, and lib contains the library named libcalc.c.

编辑：我想通了这个错误，这是在的src 未创建 OBJ 目录。但是，它仍然没有工作。新的错误信息是：

I figured out this error, and it was that the obj directory under src wasn't created. However, it's still not working. The new error message is:

make: *** No rule to make target `obj/libcalc.o', needed by `calc'.  Stop.

编辑2：我刚刚搬进从lib中libcalc.c到obj它工作得很好。不理想，但它确实是我所需要的。

EDIT 2: I just moved the libcalc.c from lib to obj and it worked fine. Not ideal, but it does what I need.

推荐答案

的 OBJ 目录不存在，那么 GCC 无法写入输出文件存在。

The obj directory doesn't exist, so gcc cannot write the output file there.

您可以从Makefile中自动创建它，但是这取决于你想要做什么，一个简单的的mkdir OBJ 可能是你所需要的。

You could create it automatically from the Makefile, but depending on what you want to do, a simple mkdir obj might be all you need.

不过，它看起来像你从的src 目录中运行你的Makefile。有可能到头来你想从你的项目的根目录中运行它，并指定的src / 在需要的地方。你会希望为添加 SDIR 变量（或类似）;确保删除 ../ 在 LDIR ， IDIR 和 ODIR 在这种情况下。

However, it looks like you are running your Makefile from the src directory. Chances are you want to run it from your project's root directory and specify src/ where needed. You'd want to add an SDIR variable (or similar) for that; make sure to remove the ../ on LDIR, IDIR and ODIR in that case.

例如，您目前使用。％，C ，使用 $（SDIR）/。％，C 代替，并适当移动你的Makefile。

For example, where you currently use %.c, use $(SDIR)/%.c instead, and move your Makefile appropriately.

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