[英]g++ can't find headers but I did include them
I am starting on c++ and already going wrong ... 我从C ++开始,已经出错了...
I am trying to compile a small test of levelDB : 我正在尝试对levelDB进行一次小型测试:
#include <assert.h>
#include "leveldb/db.h"
using namespace std;
int main() {
leveldb::DB* db;
leveldb::Options options;
options.create_if_missing = true;
leveldb::Status status = leveldb::DB::Open(options, "/tmp/testdb", &db);
assert(status.ok());
return 1;
}
Here is the g++ command : 这是g ++命令:
g++ -I include/ testLevelDB.cpp
Output: 输出:
/tmp/ccuBnfE7.o: In function `main':
testLevelDB.cpp:(.text+0x14): undefined reference to `leveldb::Options::Options()'
testLevelDB.cpp:(.text+0x57): undefined reference to `leveldb::DB::Open(leveldb::Options const&, std::string const&, leveldb::DB**)'
The include folder is the one with the levelDB headers. include文件夹是带有levelDB标头的文件夹。
You need to tell the linker to link to the leveldb
library such as 您需要告诉链接器链接到leveldb
库,例如
g++ -I include/ testLevelDB.cpp -lleveldb
But this won't work if the library is not in /usr/lib
or /usr/local/lib
for that case assuming the libleveldb.so exists in some path called $LEVELDB_PATH
you need to do 但是,如果在这种情况下该库不在/usr/lib
或/usr/local/lib
,则这将不起作用,假设libleveldb.so存在于名为$LEVELDB_PATH
某个路径中,则需要执行此操作
g++ -I include -L $LEVELDB_PATH testLevelDB.cpp -lleveldb
-L
is much like -I
but it tells the linker where to looks for libraries. -L
很像-I
但是它告诉链接器在哪里寻找库。
Also since you seem to be new to gcc world, please have a look at this gcc intro document. 另外,由于您似乎不熟悉gcc世界,因此请查看此 gcc简介文档。
It is a linkage error. 这是一个链接错误。 Not related to the headers. 与标题无关。 Did you link with this lib (-l..) ? 您是否与此lib(-l ..)链接?
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.