如何在Makefile中使用LDFLAGS [英] How to use LDFLAGS in makefile

问题描述

我是Linux操作系统的新手.我正在尝试使用makefile编译.c文件.数学库必须链接.我的makefile看起来像这样:

I am new to Linux OS. I am trying to compile a .c file using a makefile. The math library has to be linked. My makefile looks like this:

CC=gcc
CFLAGS=-Wall -lm

all:client

.PHONY: clean
clean:
    rm *~ *.o client

运行make时，出现以下错误:

When I run make, I get the following error:

"undefined reference to rint"

因此它无法链接数学库.

So it is not able to link the math library.

但是当我使用显式编译时

But when I compile explicitly using

gcc client.c -lm -o client

它可以成功编译.

那么我应该如何更改我的makefile使其起作用.我已经尝试添加LDFLAGS=-lm.但是我遇到了同样的错误.

So how should I change my makefile such that it works. I have already tried adding LDFLAGS=-lm. But I get the same error.

我还应该补充一点，当我运行make时，它会扩展为

I should also add that when I run make, it expands to

gcc -Wall -lm client.c -o client

(请注意，当我以-lm结尾时显式运行gcc时，它可以工作).

(notice that when I run gcc explicitly with -lm at the end, it works).

推荐答案

您的链接器(ld)显然不喜欢make排列GCC参数的顺序，因此您必须稍微更改Makefile:

Your linker (ld) obviously doesn't like the order in which make arranges the GCC arguments so you'll have to change your Makefile a bit:

CC=gcc
CFLAGS=-Wall
LDFLAGS=-lm

.PHONY: all
all: client

.PHONY: clean
clean:
    $(RM) *~ *.o client

OBJECTS=client.o
client: $(OBJECTS)
    $(CC) $(CFLAGS) $(OBJECTS) -o client $(LDFLAGS)

在定义 client 目标的行中，根据需要更改$(LDFLAGS)的顺序.

In the line defining the client target change the order of $(LDFLAGS) as needed.

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