未定义的引用'PQconnectdb'

最近我正在处理的项目需要添加postgresql支持。项目用C语言编写（其开源代码为Janus gateway）。未定义的引用'PQconnectdb'

我按照以下步骤安装postgress和libps-dev。

sudo apt-get install postgresql 
sudo apt-get install libpq-dev 
$ sudo -u postgres psql postgres 
psql (9.3.9) 
Type "help" for help. 

postgres=# \password postgres

然后在我的头（connect.h）文件：

#include <postgresql/libpq-fe.h> 
#include "debug.h" 

/*! \brief Connect to postgresql database 
* If successfull, returns PGconn type 
* If not exits the program 
* @param[in] postgres connection params, ex. username, db, host, etc. 
*/ 
PGconn *connect_to_database(gchar connection_params); 

/*! \brief Closes connection to database 
* @param[in] PGconn instance 
*/ 
PGconn *close_connection_to_database(PGconn *pgconn);

我的.C（connect.c）文件：

/*! \file db.c 
* \author ... 
* \copyright GNU General Public License v3 
* \brief Event handler notifications (headers) 
* \details This file contains methods for safely creating databse connection 
* to postgresql and then closing it. 
* 
* \ingroup db 
* \ref db 
*/ 

#include "./connect.h" 

PGconn *connect_to_database(gchar connection_params) { 
    JANUS_LOG(LOG_WARN, "TESTINGSSS \n\n\n\n"); 


    const char test_connect = "testings"; 

    PGconn *conn = PQconnectdb(test_connect); 

    return conn; 
}

在make我得到：

[email protected] ~/Projects/janus-gateway $ make 
make all-recursive 
make[1]: Entering directory '/home/todns/Projects/janus-gateway' 
Making all in html 
make[2]: Entering directory '/home/todns/Projects/janus-gateway/html' 
make[2]: Nothing to be done for 'all'. 
make[2]: Leaving directory '/home/todns/Projects/janus-gateway/html' 
make[2]: Entering directory '/home/todns/Projects/janus-gateway' 
    CCLD  janus 
db/janus-connect.o: In function `connect_to_database': 
/home/todns/Projects/janus-gateway/db/connect.c:20: undefined reference to `PQconnectdb' 
collect2: error: ld returned 1 exit status 
Makefile:1195: recipe for target 'janus' failed 
make[2]: *** [janus] Error 1 
make[2]: Leaving directory '/home/todns/Projects/janus-gateway' 
Makefile:1914: recipe for target 'all-recursive' failed 
make[1]: *** [all-recursive] Error 1 
make[1]: Leaving directory '/home/todns/Projects/janus-gateway' 
Makefile:905: recipe for target 'all' failed 
make: *** [all] Error 2

问题是：

db/janus-connect.o: In function `connect_to_database': 
    /home/todns/Projects/janus-gateway/db/connect.c:20: undefined

我的直觉告诉我，它与Makefile.am文件有关，但我真的不知道该怎么改。所以问题是：我在这个设置中缺少什么？我如何将postgres-dev库与我的C代码链接起来？

谢谢！忘了提及，我在Linux Mint虚拟机（主机是MacBook Pro）上运行此操作。

来源

2017-02-20 IvRRimUm

是Makefile文件与'#include“./connect.h”'在同一个目录下？可能不会。也许你必须把'#include“./connect.h”'改成正确的路径。或者，改变'-I'目录。 –

@FiddlingBits'connect.c'和'connect.h'位于同一个目录下，名为db。 – IvRRimUm

@FiddlingBits我如何更改'-I'目录？在哪里做，如何？ – IvRRimUm

想通了。

追加-L/.... -psql到AM_CFLAGS Makefile.am

继承人的全系列：

AM_CFLAGS += -fstack-protector-all -g -ggdb -fPIC -rdynamic -pthread -L/usr/include/postgresql/libpq -lpq

您可以检查出剑锋网关Makefile.am看到我Makefile.am的外观没有-psql

来源

2017-02-20 17:19:53 IvRRimUm

未定义的引用'PQconnectdb'

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