c++ - 构建缺少错误 mysqlcppconn 的 C++ 脚本(没有这样的文件)

Question

有一个 c++ 新手。

我想为 Raspi 3 的 C++ 开发准备工作环境。这包括 C++(windows 上的 netbeans IDE，Raspi 上的 geany)、mysql (mariDB) 和 QT。

第一步是在 raspi 上编写一个简单的脚本“hello world”，然后在 cppconn 的帮助下进行构建。第二步是在 Netbeans IDE 中的 Windows 上制作相同的脚本，并在本地/远程构建它。

我有这个简单的脚本:

    /*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

/* 
 * File:   main.cpp
 * Author: marek
 *
 * Created on 1. listopadu 2017, 22:33
 */

#include <iostream>
#include <cstdlib>
#include <stdlib.h>

/*
  Include directly the different
  headers from cppconn/ and mysql_driver.h + mysql_util.h
  (and mysql_connection.h). This will reduce your build time!
*/
#include <mysql_connection.h>
#include <mysql_driver.h>

#include <cppconn/driver.h>
#include <cppconn/exception.h>
#include <cppconn/resultset.h>
#include <cppconn/statement.h>



using namespace std;

/*
 * 
 */
int main(int argc, char** argv) {

cout << endl;
cout << "running select as a messege" << endl;

try {
  sql::Driver *driver;
  sql::Connection *con;
  sql::Statement *stmt;
  sql::ResultSet *res;

  /* Create a connection */
  driver = get_driver_instance();
  con = driver->connect("tcp://10.0.0.6:3306", "root", "FTQERJSC");

  /* Connect to the MySQL test database */
  con->setSchema("mysql");

  stmt = con->createStatement();
  res = stmt->executeQuery("SELECT 'Hello World!' AS _message");
  while (res->next()) {
    cout << "\t... MySQL replies: ";
    /* Access column data by alias or column name */
    cout << res->getString("_message") << endl;
    cout << "\t... MySQL says it again: ";
    /* Access column data by numeric offset, 1 is the first column */
    cout << res->getString(1) << endl;
  }
  delete res;
  delete stmt;
  delete con;

} catch (sql::SQLException &e) {
  cout << "̣# ERR: SQLException in "    << __FILE__; 
  cout << "(" << __FUNCTION__ << ") on line " << __LINE__ << endl; 
  cout << "̣# ERR: " << e.what(); 
  cout << " (MySQL error code: " << e.getErrorCode();
  cout << ", SQLState: " << e.getSQLState() << ")" << endl; 
}

cout << endl;

return EXIT_SUCCESS;




std::cout << "hello world pc 5 mysql\n"; 

#ifdef __linux__ 
    std::cout << "__linux__\n";  
#elif defined(__unix__)
    std::cout << "__unix__\n";  
#elif defined(_WIN64)
    std::cout << "_WIN64\n";  
#elif defined(_WIN32)
    std::cout << "_WIN32\n";  
#endif


#if __WORDSIZE == 64 
    std::cout << "64 bit\n";
#else 
    std::cout << "32 bit\n";  
#endif

    return 0;
}

在构建过程中我遇到了这些错误:

cd 'C:\Users\marek\Documents\c++ projects\hello-world-7-pc-mysql'
C:\msys\1.0\bin\make.exe -f Makefile CONF=Debug
"/C/msys/1.0/bin/make.exe" -f nbproject/Makefile-Debug.mk QMAKE= SUBPROJECTS= .build-conf
make.exe[1]: Entering directory `/c/Users/marek/Documents/c++ projects/hello-world-7-pc-mysql'
"/C/msys/1.0/bin/make.exe"  -f nbproject/Makefile-Debug.mk dist/Debug/MinGW_Qt-Windows/hello-world-7-pc-mysql.exe
make.exe[2]: Entering directory `/c/Users/marek/Documents/c++ projects/hello-world-7-pc-mysql'
mkdir -p dist/Debug/MinGW_Qt-Windows
g++     -o dist/Debug/MinGW_Qt-Windows/hello-world-7-pc-mysql build/Debug/MinGW_Qt-Windows/main.o -L/C/Program\ Files/MySQL/MySQL\ Connector\ C++\ 1.1.9/lib -L/C/Program\ Files/MySQL/MySQL\ Connector\ C++\ 1.1.9/include/cppconn -L/C/Program\ Files/MySQL/MySQL\ Connector\ C++\ 1.1.9/include -lmysqlcppconn-static -lmysqlcppconn "/C/Program Files/MySQL/MySQL Connector C++ 1.1.9/lib/opt/mysqlcppconn-static.lib" "/C/Program Files/MySQL/MySQL Connector C++ 1.1.9/lib/opt/mysqlcppconn.lib" -lmysqlcppconn  
c:/Qt/Qt5.9.2/Tools/mingw530_32/bin/../lib/gcc/i686-w64-mingw32/5.3.0/../../../../i686-w64-mingw32/bin/ld.exe: cannot find -lmysqlcppconn-static
c:/Qt/Qt5.9.2/Tools/mingw530_32/bin/../lib/gcc/i686-w64-mingw32/5.3.0/../../../../i686-w64-mingw32/bin/ld.exe: cannot find -lmysqlcppconn
c:/Qt/Qt5.9.2/Tools/mingw530_32/bin/../lib/gcc/i686-w64-mingw32/5.3.0/../../../../i686-w64-mingw32/bin/ld.exe: cannot find -lmysqlcppconn
collect2.exe: error: ld returned 1 exit status
make.exe[2]: *** [dist/Debug/MinGW_Qt-Windows/hello-world-7-pc-mysql.exe] Error 1
make.exe[2]: Leaving directory `/c/Users/marek/Documents/c++ projects/hello-world-7-pc-mysql'
make.exe[1]: *** [.build-conf] Error 2
make.exe[1]: Leaving directory `/c/Users/marek/Documents/c++ projects/hello-world-7-pc-mysql'
make.exe": *** [.build-impl] Error 2

BUILD FAILED (exit value 2, total time: 858ms)

对于为 C++ 编码设置 Mysql 感到非常沮丧。

请指教:)

谢谢，马立克

Answer 1

我重新格式化了您的命令行和错误消息以提高可读性(特别是我放入了换行符，并将路径规范化为 ld)。

g++ -o dist/Debug/MinGW_Qt-Windows/hello-world-7-pc-mysql \ 
   build/Debug/MinGW_Qt-Windows/main.o \
  -L/C/Program\ Files/MySQL/MySQL\ Connector\ C++\ 1.1.9/lib \
  -L/C/Program\ Files/MySQL/MySQL\ Connector\ C++\ 1.1.9/include/cppconn \
  -L/C/Program\ Files/MySQL/MySQL\ Connector C++\ 1.1.9/include \
  -lmysqlcppconn-static \
  -lmysqlcppconn \
  "/C/Program Files/MySQL/MySQL Connector C++ 1.1.9/lib/opt/mysqlcppconn-static.lib" \
  "/C/Program Files/MySQL/MySQL Connector C++ 1.1.9/lib/opt/mysqlcppconn.lib" \
  -lmysqlcppconn
c:/Qt/Qt5.9.2/Tools/i686-w64-mingw32/bin/ld.exe: cannot find -lmysqlcppconn-static
c:/Qt/Qt5.9.2/Tools/i686-w64-mingw32/bin/ld.exe: cannot find -lmysqlcppconn
c:/Qt/Qt5.9.2/Tools/i686-w64-mingw32/bin/ld.exe: cannot find -lmysqlcppconn

首先要说的是 ld 找不到调用 -lmysqlconn 的文件。这很奇怪，因为通常情况下，-l 表示“加载名为 libmysqlconn 的库，类型为 .a 或 .so”。但是，您的命令行有许多非常奇怪的地方:

首先，-L 是命令行选项，用于指定在哪里可以找到库(.lib、.so、.a、.dll)——那你为什么要指定包含目录？

其次，为什么要同时指定 -lmysqlconn-static 和 -lmysqlconn？您要么想要一个静态库，要么想要一个动态库 - 而不是两者。

第三，您为什么要明确指定库名称(在 /C/... 行中)。

第四，为什么要指定两次-lmysqlcppconn？

我认为您需要将命令行更改为:

g++ -o dist/Debug/MinGW_Qt-Windows/hello-world-7-pc-mysql \ 
  -L/C/Program\ Files/MySQL/MySQL\ Connector\ C++\ 1.1.9/lib \
  -lmysqlcppconn \
  build/Debug/MinGW_Qt-Windows/main.o

最后，我认为您需要仔细阅读 Qt 教程。此刻，你似乎只是在四处游荡。