在Ubuntu 11.10中使用gcc编译时对openssl函数的未定义引用 [英] Undefined reference to openssl functions when compiling with gcc in Ubuntu 11.10

问题描述

在Ubuntu 11.10 x86_64中，我有这个简单的test.c文件:

In Ubuntu 11.10 x86_64 I have this this simple test.c file:

#include <openssl/ssl.h>

int main() {
    SSL_library_init();
    return 0;
}

为什么用gcc编译失败?

Why does compiling with gcc fail?

$ gcc -lssl -lcrypto test.c
/tmp/ccqL6lRY.o: In function `main':
test.c:(.text+0x5): undefined reference to `SSL_library_init'
collect2: ld returned 1 exit status

使用clang进行编译会产生可运行的可执行文件:

Compiling with clang works and produces a working executable:

$ clang -lssl -lcrypto test.c
$ ldd a.out 
linux-vdso.so.1 =>  (0x00007fffa93e1000)
libssl.so.1.0.0 => /lib/x86_64-linux-gnu/libssl.so.1.0.0 (0x00007f234a24f000)
libcrypto.so.1.0.0 => /lib/x86_64-linux-gnu/libcrypto.so.1.0.0 (0x00007f2349ea0000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f2349b00000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f23498fc000)
libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f23496e4000)
/lib64/ld-linux-x86-64.so.2 (0x00007f234a4c4000

推荐答案

尝试将-lssl放在末尾(在test.c之后).

Try to put -lssl at the end (after test.c).

$ gcc test.c -lssl -lcrypto

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