[英]How to use external libraries and headers in C Makefile?
I have a header file myheader.h and a static library libmylib.a file in directory1. 我有一个头文件myheader.h和一个在directory1中的静态库libmylib.a文件。 In directory2, I'm writing a program which uses them. 在directory2中,我正在编写一个使用它们的程序。 Suppose I have main.c in directory2 which uses myheader.h and libmylib.a. 假设我在directory2中有main.c,它使用myheader.h和libmylib.a。 How do I create a Makefile to compile and link them? 如何创建Makefile来编译和链接它们?
Right now, in my main.c, I have added 现在,在我的main.c中,我补充说
#include "../directory1/myheader.h"
Here's my Makefile at the moment: 这是我的Makefile:
CC = gcc
INCLUDES = -I
CFLAGS = -g -Wall $(INCLUDES)
main: main.o ../directory1/libmylib.a
$(CC) main.o ../directory1/libmylib.a -o main
main.o: main.c ../directory1/myheader.h
$(CC) $(CFLAGS) -c main.c
I'm getting the following warning: 我收到以下警告:
gcc -g -Wall -I -c main.c
/home/me/directory2/main.c:72: undefined reference to `foo'
collect2: ld returned 1 exit status
make: *** [main.o] Error 1
where foo is one of the functions in the library. 其中foo是库中的一个函数。
Ok. 好。 Fixed it. 固定它。
I removed #include "../directory1/myheader.h"
and replaced it with #include "myheader.h"
. 我删除了#include "../directory1/myheader.h"
#include "myheader.h"
并将其替换为#include "myheader.h"
。
Then in the Makefile, I used: 然后在Makefile中,我使用了:
CC = gcc
INCLUDES = -I../directory1
CFLAGS = -g -Wall $(INCLUDES)
LDFLAGS = -L../directory1
main: main.o ../directory1/libmylib.a
$(CC) main.o $(LDFLAGS) -lmylib -o main
main.o: main.c ../directory1/myheader.h
$(CC) $(CFLAGS) -c main.c
Using -lmylib
will be a problem. 使用-lmylib
将是一个问题。 For non-static libraries you would need to fiddle with the variable LD_LIBRARY_PATH; 对于非静态库,您需要使用变量LD_LIBRARY_PATH; see Why do I have to define LD_LIBRARY_PATH with an export every time I run my application? 为什么每次运行我的应用程序时都必须使用导出定义LD_LIBRARY_PATH? . 。 You could fix your makefile by adding -L ../directory1
. 您可以通过添加-L ../directory1
来修复您的makefile。 But the simplest thing is just replace -lmylib
with ../directory1/libmylib.a
. 但最简单的事情是只需更换-lmylib
与../directory1/libmylib.a
。
For example: 例如:
directory1/mylib.c directory1中/ mylib.c
#include "../directory1/myheader.h"
void foo(void) {}
directory1/Makefile directory1中/ Makefile文件
libmylib.a: mylib.o
ar r $@ $?
directory1/main.c: directory1中/ main.c中:
#include "../directory1/myheader.h"
int main(void) {
foo();
return 0;
}
directory1/Makefile directory1中/ Makefile文件
main: main.o ../directory1/libmylib.a
gcc main.o ../directory1/libmylib.a -o main
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