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Testing for empty or nil-value string [duplicate]
...lse (because of short-circuiting).
This should be sufficient:
variable = id if variable.nil? || variable.empty?
If you're working with Ruby on Rails, Object.blank? solves this exact problem:
An object is blank if it’s false, empty, or a whitespace string. For example, "", " ", nil, [], a...
check / uncheck checkbox using jquery? [duplicate]
...ou know, in HTML, it would look something like:
<input type="checkbox" id="myCheckbox" checked="checked" /> <!-- Checked -->
<input type="checkbox" id="myCheckbox" /> <!-- Unchecked -->
However, you cannot trust the .attr() method to get the value of the checkbox (if you n...
Swift equivalent of [NSBundle bundleForClass:[self class]]
... Autocomplete in the current version of Xcode acts like it has no idea what you're talking about, but it does indeed work.
– David Beck
Oct 7 '14 at 21:52
4
...
MFC AFX_WM_CREATETOOLBAR消息相关 - C/C++ - 清泛网 - 专注C/C++及内核技术
...
BEGIN_MESSAGE_MAP(CMainFrame, CMDIFrameWndEx)
ON_WM_CREATE()
ON_COMMAND(ID_WINDOW_MANAGER, &CMainFrame::OnWindowManager)
ON_COMMAND(ID_VIEW_CUSTOMIZE, &CMainFrame::OnViewCustomize)
ON_REGISTERED_MESSAGE(AFX_WM_CREATETOOLBAR, &CMainFrame::OnToolbarCreateNew)
END_MESSAGE_MAP()
触发事件： ...
MFC MDI切换menu原理 - C/C++ - 清泛网 - 专注C/C++及内核技术
...向导生成的SDI或MDI应用程序时，它创建了菜单资源（使用IDR_MAINFRAME作为其资源id。此菜单显示在所有时间SDI应用程序，并且仅在...当应用程序向导生成的 SDI 或 MDI 应用程序时，它创建了菜单资源 （使用 IDR_MAINFRAME 作为其资源 id...
ON_COMMAND_EX、ON_COMMAND区别 - C/C++ - 清泛网 - 专注C/C++及内核技术
...定义的消息处理函数解释该参数是当前要处理的命令消息ID。
返回值：如果扩展映射宏的消息处理函数返回FALSE，则导致当前消息被发送给消息路径上的下一个消息目标处理。
综合来看，ON_COMMAND_EX宏有两个功能：
一是可以...
MFC MDI程序的窗口菜单无法正确显示 - C/C++ - 清泛网 - 专注C/C++及内核技术
...n looks for a pop-up menu containing standard Window menu commands such as ID_WINDOW_NEW and ID_WINDOW_TILE_HORZ.Override this member function if you have a Window menu that does not use the standard menu command IDs.
所以，只需要覆盖函数CMDIFrameWnd::GetWindowMenuPopup就可以解决问...
常用Sql - 数据库(内核) - 清泛网 - 专注C/C++及内核技术
...ists tablename;
mysql：建立索引Sql
CREATE TABLE tablename (
`ID` decimal(18,0) NOT NULL COMMENT '递增ID',
`FIELD_1` varchar(32) NOT NULL COMMENT '字段1',
`FIELD_2` varchar(32) NOT NULL COMMENT '字段2',
...
SQL中使用update inner join和delete inner join；Oracle delete join替代...
...tb_User usr
inner join tb_Address addr on usr.nAddressFK = addr.nAddressID
where usr.id=123
update的格式是
update t1 set t1.name=’Liu’ from t1 inner join t2 on t1.id = t2.tid
MySQL，ACCESS 写法如下：
Sql代码
UPDATE mem_world AS mw1 INNER JOIN mem_world AS ...
phpcms v9内容页/下载页更新时间（updatetime）为空的解决方法 - 更多技术 ...
... define('INDEX_HTML',true);
$catid = $_POST['info']['catid'] = intval($_POST['info']['catid']);
if(trim($_POST['info']['title'])=='') showmessage(L('title_is_empty'));
$category = $this->categorys[$catid];
...