如何在c++中循环std::map ?我的地图被定义为:

std::map< std::string, std::map<std::string, std::string> >

例如，上面的容器保存的数据是这样的:

m["name1"]["value1"] = "data1";
m["name1"]["value2"] = "data2";
m["name2"]["value1"] = "data1";
m["name2"]["value2"] = "data2";
m["name3"]["value1"] = "data1";
m["name3"]["value2"] = "data2";

我如何通过这个映射循环并访问各种值?

我想一次遍历一个Python列表并处理2个列表项。在另一种语言中是这样的:

for(int i = 0; i < list.length(); i+=2)
{
   // do something with list[i] and list[i + 1]
}

实现这一目标的最佳方法是什么?

AFAIK，有两种方法:

迭代集合的副本 使用实际集合的迭代器

例如,

List<Foo> fooListCopy = new ArrayList<Foo>(fooList);
for(Foo foo : fooListCopy){
    // modify actual fooList
}

and

Iterator<Foo> itr = fooList.iterator();
while(itr.hasNext()){
    // modify actual fooList using itr.remove()
}

是否有任何理由偏爱一种方法而不是另一种方法(例如，出于可读性的简单原因而偏爱第一种方法)?

我有一个div，它有几个输入元素在它…我想要遍历每一个元素。想法吗?

我希望能够运行单个规范文件的测试—例如，对于我正在编辑的一个文件。Rake spec执行所有的规范。我的项目不是Rails项目，所以rake spec:doc不起作用。

不知道这是否重要，但这是我的目录结构。

./Rakefile
./lib
./lib/cushion.rb
./lib/cushion
./lib/cushion/doc.rb
./lib/cushion/db.rb
./spec
./spec/spec.opts
./spec/spec_helper.rb
./spec/db_spec.rb

在ios7中，sizeWithFont:现在已弃用。我现在如何在UIFont对象传递到替换方法sizeWithAttributes:?

我想循环遍历数组中包含的对象，并更改每个对象的属性。如果我这样做:

for (var j = 0; j < myArray.length; j++){

console.log(myArray[j]);

}

控制台应该显示数组中的每个对象，对吧?但实际上它只显示第一个对象。如果我在循环外对数组进行console日志记录，所有的对象都会出现，所以里面肯定有更多的对象。

不管怎样，这是下一个问题。我如何访问，例如Object1。X在数组中，使用循环?

for (var j = 0; j < myArray.length; j++){

console.log(myArray[j.x]);

}

这将返回“undefined”。循环外的控制台日志再次告诉我，所有对象都有“x”的值。如何在循环中访问这些属性?

其他地方建议我为每个属性使用单独的数组，但我想先确保我已经用尽了这个方法。

谢谢你！

所以我有一个ng-repeat嵌套在另一个ng-repeat中，以构建一个导航菜单。在内部ng-repeat循环的每个<li>上，我设置了一个ng-click，通过传入$index来调用该菜单项的相关控制器，让应用程序知道我们需要哪个。然而，我还需要从外部ng-repeat传递$index，以便应用程序知道我们在哪个部分以及哪个教程。

<ul ng-repeat="section in sections">
    <li  class="section_title {{section.active}}" >
        {{section.name}}
    </li>
    <ul>
        <li class="tutorial_title {{tutorial.active}}" ng-click="loadFromMenu($index)" ng-repeat="tutorial in section.tutorials">
            {{tutorial.name}}
        </li>
    </ul>
</ul>

这是普伦克http://plnkr.co/edit/bJUhI9oGEQIql9tahIJN?p=preview

I noticed that when I place a white or black UIImage into a UISegmentedControl it automatically color masks it to match the tint of the segmented control. I thought this was really cool, and was wondering if I could do this elsewhere as well. For example, I have a bunch of buttons that have a uniform shape but varied colors. Instead of making a PNG for each button, could I somehow use this color masking to use the same image for all of them but then set a tint color or something to change their actual color?

I'm an iOS developer with some experience and this question is really interesting to me. I saw a lot of different resources and materials on this topic, but nevertheless I'm still confused. What is the best architecture for an iOS networked application? I mean basic abstract framework, patterns, which will fit every networking application whether it is a small app which only have a few server requests or a complex REST client. Apple recommends to use MVC as a basic architectural approach for all iOS applications, but neither MVC nor the more modern MVVM patterns explain where to put network logic code and how to organize it in general. Do I need to develop something like MVCS(S for Service) and in this Service layer put all API requests and other networking logic, which in perspective may be really complex? After doing some research I found two basic approaches for this. Here it was recommended to create a separate class for every network request to web-service API (like LoginRequest class or PostCommentRequest class and so on) which all inherits from the base request abstract class AbstractBaseRequest and in addition to create some global network manager which encapsulates common networking code and other preferences (it may be AFNetworking customisation or RestKit tuning, if the we have complex object mappings and persistence, or even an own network communication implementation with standard API). But this approach seems an overhead for me. Another approach is to have some singleton API dispatcher or manager class as in the first approach, but not to create classes for every request and instead to encapsulate every request as an instance public method of this manager class like: fetchContacts, loginUser methods, etc. So, what is the best and correct way? Are there other interesting approaches I don't know yet? And should I create another layer for all this networking stuff like Service, or NetworkProvider layer or whatever on top of my MVC architecture, or this layer should be integrated (injected) into existing MVC layers e.g. Model? I know there exists beautiful approaches, or how then such mobile monsters like Facebook client or LinkedIn client deal with exponentially growing complexity of networking logic? I know there are no exact and formal answer to the problem. The goal of this question is to collect the most interesting approaches from experienced iOS developers. The best suggested approach will be marked as accepted and awarded with a reputation bounty, others will be upvoted. It is mostly a theoretical and research question. I want to understand basic, abstract and correct architectural approach for networking applications in iOS. I hope for detailed explanation from experienced developers.