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GCC4.1.2 �?临时对象作�ؓ参数传递给 const T& �~�译报错

zaccheo — Wed, 30 Oct 2013 08:38:00 GMT

Copy constructor access check while initializing a reference.

Consider this code:

class A 
{
public:
  A();

private:
  A(const A&);   // private copy ctor
};

A makeA(void);
void foo(const A&);

void bar(void)
{
  foo(A());       // error, copy ctor is not accessible
  foo(makeA());   // error, copy ctor is not accessible

  A a1;
  foo(a1);        // OK, a1 is a lvalue
}

Starting with GCC 3.4.0, binding an rvalue to a const reference requires an accessible copy constructor. This might be surprising at first sight, especially since most popular compilers do not correctly implement this rule.

The C++ Standard says that a temporary object should be created in this context and its contents filled with a copy of the object we are trying to bind to the reference; it also says that the temporary copy can be elided, but the semantic constraints (eg. accessibility) of the copy constructor still have to be checked.

For further information, you can consult the following paragraphs of the C++ standard: [dcl.init.ref]/5, bullet 2, sub-bullet 1, and [class.temporary]/2.

Starting with GCC 4.3.0, GCC no longer gives an error for this case. This change is based on the intent of the C++ language committee. As of 2010-05-28, the final proposed draft of the C++0x standard permits this code without error.

zaccheo 2013-10-30 16:38 发表评论

zaccheo — Wed, 24 Apr 2013 02:30:00 GMT

MFC开发的OCX控�g即��使用了签名。在IE中运行是也会提示“页面中的OCX的交互是不安全的。。。。”。解军_��法有两种

�Ҏ��1�Q�修改IE的设�|�：

�Ҏ��2�Q�标记控件�ؓ脚本安全�?/p>

在工�E�中增加头文�?cathelp.h

#ifndef _CATHELP_H_
#define _CATHELP_H_
#include 
HRESULT CreateComponentCategory(CATID catid, WCHAR* catDescription);
HRESULT RegisterCLSIDInCategory(REFCLSID clsid, CATID catid);
HRESULT UnRegisterCLSIDInCategory(REFCLSID clsid, CATID catid);
#endif

增加cathelp.cpp

#include "cathelp.h"
HRESULT CreateComponentCategory(CATID catid, WCHAR* catDescription)
{
	
    ICatRegister* pcr = NULL ;
    HRESULT hr = S_OK ;
	
    hr = CoCreateInstance(CLSID_StdComponentCategoriesMgr, 
		NULL, CLSCTX_INPROC_SERVER, IID_ICatRegister, (void**)&pcr);
	if (FAILED(hr))
		return hr;
	
    // Make sure the HKCR\Component Categories\{..catid...}
    // key is registered
    CATEGORYINFO catinfo;
    catinfo.catid = catid;
    catinfo.lcid = 0x0409 ; // english
	
	// Make sure the provided description is not too long.
	// Only copy the first 127 characters if it is
	int len = wcslen(catDescription);
	if (len>127)
		len = 127;
    wcsncpy(catinfo.szDescription, catDescription, len);
	// Make sure the description is null terminated
	catinfo.szDescription[len] = '\0';
	
	if(pcr)
	{
		hr = pcr->RegisterCategories(1, &catinfo);
		pcr->Release();
	}
	
	return hr;
}
HRESULT RegisterCLSIDInCategory(REFCLSID clsid, CATID catid)
{
	// Register your component categories information.
    ICatRegister* pcr = NULL ;
    HRESULT hr = S_OK ;
    hr = CoCreateInstance(CLSID_StdComponentCategoriesMgr, 
		NULL, CLSCTX_INPROC_SERVER, IID_ICatRegister, (void**)&pcr);
    if (SUCCEEDED(hr))
    {
		// Register this category as being "implemented" by
		// the class.
		CATID rgcatid[1] ;
		rgcatid[0] = catid;
		hr = pcr->RegisterClassImplCategories(clsid, 1, rgcatid);
    }
	
    if (pcr != NULL)
        pcr->Release();
	
	return hr;
}
HRESULT UnRegisterCLSIDInCategory(REFCLSID clsid, CATID catid)
{
    ICatRegister* pcr = NULL ;
    HRESULT hr = S_OK ;
    hr = CoCreateInstance(CLSID_StdComponentCategoriesMgr, 
		NULL, CLSCTX_INPROC_SERVER, IID_ICatRegister, (void**)&pcr);
    if (SUCCEEDED(hr))
    {
		// Unregister this category as being "implemented" by
		// the class.
		CATID rgcatid[1] ;
		rgcatid[0] = catid;
		hr = pcr->UnRegisterClassImplCategories(clsid, 1, rgcatid);
    }
	
    if (pcr != NULL)
        pcr->Release();
	
	return hr;
}

修改 ocx�?DllRegisterServer �Ҏ��

#include "cathelp.h"
#include //for CATID_SafeForInitializing
#include "SafeocxtestCtl.h"
STDAPI DllRegisterServer(void)
{
	AFX_MANAGE_STATE(_afxModuleAddrThis);
	if (!AfxOleRegisterTypeLib(AfxGetInstanceHandle(), _tlid))
		return ResultFromScode(SELFREG_E_TYPELIB);
	if (!COleObjectFactoryEx::UpdateRegistryAll(TRUE))
		return ResultFromScode(SELFREG_E_CLASS);
	// 注册脚本安全
	if( FAILED( CreateComponentCategory(CATID_SafeForScripting, L"Controls that are safely scriptable") ) )
		return ResultFromScode(SELFREG_E_CLASS);
	
	if( FAILED( CreateComponentCategory(CATID_SafeForInitializing, L"Controls safely initializable from persistent data") ) )
		return ResultFromScode(SELFREG_E_CLASS);
	if (FAILED( RegisterCLSIDInCategory(
		CSafeocxtestCtrl::guid, CATID_SafeForScripting) ))
		return ResultFromScode(SELFREG_E_CLASS);
	
	if (FAILED( RegisterCLSIDInCategory(
		CSafeocxtestCtrl::guid, CATID_SafeForInitializing) ))
                return ResultFromScode(SELFREG_E_CLASS);
    
	return NOERROR;
}
/////////////////////////////////////////////////////////////////////////////
// DllUnregisterServer - Removes entries from the system registry
STDAPI DllUnregisterServer(void)
{
	AFX_MANAGE_STATE(_afxModuleAddrThis);
	if (!AfxOleUnregisterTypeLib(_tlid, _wVerMajor, _wVerMinor))
		return ResultFromScode(SELFREG_E_TYPELIB);
	if (!COleObjectFactoryEx::UpdateRegistryAll(FALSE))
		return ResultFromScode(SELFREG_E_CLASS);
	// 控�g安全反初始化
    UnRegisterCLSIDInCategory(	CSafeocxtestCtrl::guid, CATID_SafeForScripting);
    UnRegisterCLSIDInCategory(	CSafeocxtestCtrl::guid, CATID_SafeForInitializing);
    
   
	return NOERROR;
}

�~�译注册��OK了�?/p>

如果要查看ocx是否是脚本安全的。在注册表HKEY_CLASSES_ROOT\CLSID\OCX的clsid\Implemented Categories\ 下看一下有没有“{7DD95801-9882-11CF-9FA9-00AA006C42C4}�?和“{7DD95802-9882-11CF-9FA9-00AA006C42C4}�?/p>

下图��是脚本安全的：

参考：http://support.microsoft.com/kb/161873/en-us

zaccheo 2013-04-24 10:30 发表评论

centos6.0 上安装codeblocks12.11

zaccheo — Tue, 09 Apr 2013 12:07:00 GMT

主要参考了 �Q?a title="http://wiki.codeblocks.org/index.php?title=Installing_Code::Blocks_from_source_on_RPM_based_distributions" >http://wiki.codeblocks.org/index.php?title=Installing_Code::Blocks_from_source_on_RPM_based_distributions

  1: #安装 依赖的开发包
  2: yum groupinstall "Development Tools"
  3: 
  4: #安装 wxGTK�Q�我�q�个使用的是2.8.*���试是可以的
  5: yum install wxGTK*
  6: 
  7: #下蝲codeblocks安装
  8: #http://www.codeblocks.org/downloads/binaries#linux 
  9: # codeblocks-12.11-1.el6.i686.tar.bz2 (CentOS/RedHat 6)
 10: 
 11: #然后是解压安�?
 12: #安装完成后，建立一个helloCB的工�E�，�q�行是提�C?xTerm -T ��p�|。。�?
 13: #于是
 14: yum install xterm
 15: # 完成
 16:

zaccheo 2013-04-09 20:07 发表评论

centos 5.6 安装mysql

zaccheo — Fri, 29 Mar 2013 07:52:00 GMT

  1: #!/bin/sh
  2: 	rpm -ivh mysql-5.0.77-4.el5_5.4.i386.rpm  --nodeps
  3: 	rpm -ivh perl-DBI-1.52-2.el5.i386.rpm
  4: 	rpm -ivh perl-DBD-MySQL-3.0007-2.el5.i386.rpm 
  5: 	
  6: 	rpm -ivh mysql-server-5.0.77-4.el5_5.4.i386.rpm
  7: ##讄���MySQL服务随系�l�启动自启动
  8: 	chkconfig mysqld on
  9: 	echo "讄���MySQL服务随系�l�启动自启动成功"
 10: ##启动MySQL服务
 11: 	echo "启动MySQL服务成功"
 12: 	/etc/rc.d/init.d/mysqld start
 13: ##关闭Linux的防火墙功能
 14: 	echo "防火墙已关闭"
 15: 	chkconfig iptables off
 16: ##授权root �q�程
 17: 	grant all privileges on *.* to root@'%' identified 123456';
 18:

zaccheo 2013-03-29 15:52 发表评论

zaccheo — Thu, 28 Mar 2013 08:39:00 GMT

定义触发�?

  1: USE dbtest;
  2: DELIMITER ;;
  3: 
  4: CREATE TRIGGER tr_ondel_test1 AFTER DELETE ON testtable1
  5: FOR EACH ROW BEGIN
  6: DELETE FROM testtable2 where testtable2.FID= OLD.ID;
  7: END;;
  8: 
  9: DELIMITER ;

删除触发器：

  1: DROP   TRIGGER  dbtest.tr_ondel_test1;

查看触发器：

  1: SHOW TRIGGERS FROM dbtest;
  2: 
  3: SHOW TRIGGERS FROM dbtest LIKE �?ondel%�?

导出存储�q�程和触发器�Q?/p>

  1: mysqldump -u root -p123456 --default-character-set=gbk --triggers dbtest >./bk.sql

zaccheo 2013-03-28 16:39 发表评论

zaccheo — Fri, 22 Mar 2013 10:00:00 GMT

数据库默认字�W�集如下�Q?/p>

  1: mysql> use ivm;
  2: Database changed
  3: mysql> show variables %char%';
  4: +--------------------------+---------------------------------------------------------+
  5: | Variable_name            | Value                                                   |
  6: +--------------------------+---------------------------------------------------------+
  7: | character_set_client     | latin1                                                  |
  8: | character_set_connection | latin1                                                  |
  9: | character_set_database   | gbk                                                     |
 10: | character_set_filesystem | binary                                                  |
 11: | character_set_results    | latin1                                                  |
 12: | character_set_server     | latin1                                                  |
 13: | character_set_system     | utf8                                                    |
 14: | character_sets_dir       | D:\Program Files\MySQL\MySQL Server 5.0\share\charsets\ |
 15: +--------------------------+---------------------------------------------------------+
 16: 8 rows in set (0.00 sec)
 17: 
 18: mysql>

�?ivm数据库中创徏存储�q�程及调用结果如下：

  1: delimiter ;;
  2: DROP PROCEDURE IF EXISTS r_test;
  3: CREATE PROCEDURE r_test(IN inStr VARCHAR(255) )
  4: BEGIN
  5: 	SELECT CHARSET(inStr);
  6: END;;
  7: delimiter ;
  8: 
  9: #下面的语句都执行��p�|,错误信息为：Data too long for inStr' at row 1
 10: call r_test('中国');
 11: call r_test(_gbk'中国');
 12: SET @china = _gbk'中国';
 13: CALL r_test(@china);
 14: #执行成功 �q�回值是�Q�latin1
 15: call r_test('china');
 16: 
 17: 
 18: # 创徏存储�q�程中设�|�了 参数的字�W�集
 19: delimiter ;;
 20: DROP PROCEDURE IF EXISTS r_test2;
 21: CREATE PROCEDURE r_test2(IN inStr VARCHAR(255) character set gbk)
 22: BEGIN
 23: 	SELECT CHARSET(inStr);
 24: END;;
 25: delimiter ;
 26: 
 27: #执行成功 �q�回值是�Q�gbk
 28: call r_test2('中国');
 29: #执行成功 即��执行前设�|�了字符集是utf8�q�回��g��然是�Q�gbk
 30: call r_test2(_utf8'中国');
 31: #执行成功 �q�回值是�Q�gbk
 32: call r_test2('china');

�l�论�Q?strong>创徏存储�q�程时如果没有指定存储过�E�的参数的字�W�集�Q�mysql��L��认�ؓ当前的参��C��用的是系�l�的字符�?windows �?my.ini中的 default-character-set指定)�?/strong>

否则�Q�mysql��L��认�ؓ存储�q�程的参��C��用的���是定义时指定的字符集�?/strong>

需要注意的是：上面的规则和当前的连接字�W�集没有��M��的关�p�（使用mysql_options(m_pMySql, MYSQL_SET_CHARSET_NAME, "utf8")也不会改变）

zaccheo 2013-03-22 18:00 发表评论

使用PREPARE 动态执行sql语句

zaccheo — Thu, 21 Feb 2013 06:15:00 GMT

1: DROP TABLE IF EXISTS alarm;
2: CREATE TABLE alarm ( id int(11) NOT NULL auto_increment, name varchar(255) default NULL,PRIMARY KEY (id));
3:
4: INSERT INTO alarm (name) aa');
5: INSERT INTO alarm (name) bb');
6:
7: DROP procedure if exists statalarm;
8: delimiter //
9: create procedure statalarm()
10: begin
11: SET @id = '1,2';
12:
13: SET @sql = 'select * from alarm where id IN (?)';
14: PREPARE stmt FROM @sql;
15: /*
16: 注意 EXECUTE 的最�l�语句是�Q�select * from alarm where id IN ('1,2');
17: 而不�?select * from alarm where id IN (1,2);
18: �q�是因�ؓ如果用户变量的值是字符�Ԍ��在EXECUTE�?会自动的在变量的值前后加上引�?
19: */
20: EXECUTE stmt USING @id;
21: DEALLOCATE PREPARE stmt;
22: /*
23: 如果惌�� l�成select * from alarm where id IN (1,2);可以使用下面的语�?
24: */
25: SET @sql = concat('select * from alarm where id IN (',@id,')');
26: PREPARE stmt FROM @sql;
27: EXECUTE stmt ;
28: DEALLOCATE PREPARE stmt;
29:
30: end;//
31: delimiter ;

zaccheo 2013-02-21 14:15 发表评论

zaccheo — Tue, 05 Feb 2013 01:07:00 GMT

有项目A在makefile�?-lb使用了b.so �Q�b.so在makefile�?lc 使用了c.so。在�~�译A是如果没有把c.so攑ֈ�/usr/lib�?usr/local/lib下，�~�译会出错�?/p>
�W�一个解��x��案就是把c.so攑ֈ�/usr/lib�?/usr/local/lib下�?/p>
�W�二�U�解��x��案是在makefile文�g中定�?环境变量 LD_LIBRARY_PATH 讄��gؓc.so的存攄��录�?/p>

#隐式加蝲的so依赖的so如果不放�?usr/lib�?usr/local/lib下，��需要指定到 LD_LIBRARY_PATH�?br>export LD_LIBRARY_PATH=../lib:$LD_LIBRARY_PATH

zaccheo 2013-02-05 09:07 发表评论

centos ��d��中文支持

zaccheo — Sun, 03 Feb 2013 09:38:00 GMT
在虚拟机中默认设�|�安装了centos 5.8 。发��C��文显�C�的都是方块的�ؕ码。��用下面的步骤��d��了中文的支持
1 安装中文支持
#yum groupinstall "Chinese Support"

2 修改配置
# vim /etc/sysconfig/i18n
��：
LANG="en_US.UTF-8"
SYSFONT="latarcyrheb-sun16"
修改为：
LANG="zh_CN.GB18030"
LANGUAGE="zh_CN.GB18030:zh_CN.GB2312:zh_CN"
SUPPORTED="zh_CN.UTF-8:zh_CN:zh:en_US.UTF-8:en_US:en"
SYSFONT="lat0-sun16"

3 注销

zaccheo 2013-02-03 17:38 发表评论

zaccheo — Thu, 10 Jan 2013 07:15:00 GMT

foo.h

1: #ifndef _FOO_H_
2: #define _FOO_H_
3: #include
4: #include
5: #include<string>
6:
7: class foo
8: {
9: public:
10: template
11: void Saytype(const T&)
12: {
13: std::cout <<"unrecognized type !"<
14: }
15:
16: // 下面的全特化�?vc6下编译通过�Q�但g++ 4.1.2 �~�译��p�|
17: // template<>
18: // void Saytype(const int & )
19: // {
20: // std::cout<<" type is int";
21: // }
22: // g++上可以��用重载来代替全特�?/span>
23: void Saytype(const int &)
24: {
25: std::cout<<" type is int";
26: }
27: };
28:
29: #endif

main.cpp

1: #include "../include/foo.h"
2:
3: int main()
4: {
5:
6: foo f;
7: f.Saytype((unsigned int)1);
8: f.Saytype((int)1);
9:
10: return 1;
11: }

zaccheo 2013-01-10 15:15 发表评论