gcc:-L和-l选项之间的区别以及如何提供库的完整路径 [英] gcc: Difference between -L and -l option AND how to provide complete path to a library

问题描述

我是makefile的新手.因此，如果我的问题很琐碎，请接受我的道歉.

I am new to makefile stuff; so, please accept my apology if my questions are trivials.

问题1 :-L和-l选项有什么区别.

Question 1: What is the difference between -L and -l option.

问题2 :您如何提供通往某些图书馆的完整路径?例如，以下makefile中提到的"libeng"和"libmx"位于{MATLABROOT}/bin/glnxa64

Question 2: How do you provide complete path to some library? For instance, "libeng" and "libmx", mentioned in following makefile,are located at {MATLABROOT}/bin/glnxa64

# root directory of MATLAB installation
MATLABROOT="/usr/local/MATLAB/R2011b"

all: engdemo

engdemo:
    g++ ${MATLABROOT}/extern/examples/eng_mat/engdemo.cpp -o engdemo \
        -I${MATLABROOT}/extern/include \
        -L${MATLABROOT}/extern/lib -llibeng -llibmx

clean:
    rm -f engdemo *.o

更新: 以下makefile起作用:

Update: Following makefile works:

# root directory of MATLAB installation
MATLABROOT="/usr/local/MATLAB/R2011b"

all: engdemo

engdemo:
    g++ ${MATLABROOT}/extern/examples/eng_mat/engdemo.cpp -o engdemo \
        -I${MATLABROOT}/extern/include \
        #-L${MATLABROOT}/extern/lib -llibeng -llibmx
    -L${MATLABROOT}/bin/glnxa64 -llibeng \
    -L${MATLABROOT}/bin/glnxa64 -llibmx

clean:
rm -f engdemo *.o

我发现以下有关链接库的链接非常有用: http://www.cs.swarthmore.edu/~newhall/unixhelp/howto_C_libraries .html

I found following link about linking libraries very useful: http://www.cs.swarthmore.edu/~newhall/unixhelp/howto_C_libraries.html

推荐答案

您的问题是指gcc链接程序(或简称为ld). 可以在gcc的链接选项中找到说明，或ld的命令行选项.

Your question is refering to gcc linker (or simply ld). Discription can be found in in gcc's Options for Linking or ld's Command Line Options.

从文档中获取

-存档 将存档文件存档添加到要链接的文件列表. ld将在其路径列表中搜索指定的每个存档的libarchive.a的出现.

-larchive Add archive file archive to the list of files to link. ld will search its path-list for occurrences of libarchive.a for every archive specified.

-Lsearchdir 将路径searchdir添加到ld将搜索存档库和ld控制脚本的路径列表中.

-Lsearchdir Add path searchdir to the list of paths that ld will search for archive libraries and ld control scripts.

在您的示例中，您需要使用-L定义libeng和libmx库所在的路径.然后使用-l选项指示ld使用这些库.

In your example you need to use -L to define the path where libeng and libmx libraries are located. Then use -l option to instruct ld to use these libraries.

请注意，在文档中指出:

Note that in the documentation is noted that:

ld将在其路径列表中搜索指定的每个 archive 的lib archive .a的出现.

ld will search its path-list for occurrences of libarchive.a for every archive specified.

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