WebJun 15, 2024 · 遍历一个容器可以使用迭代器(iterators)来完成,迭代器提供了一个统一的方法来访问容器中的项目。. Qt的容器类提供了两种类型的迭代器:Java风格迭代器和STL风格迭代器。. 如果只是想按顺序遍历一个容器中的项目,那么还可以使用Qt的foreach关键字。. … WebThe foreach keyword is a Qt-specific addition to the C++ language, and is implemented using the preprocessor. Its syntax is: foreach (variable, container) statement. For …
QT中foreach的用法及在工程中用法示例 - CSDN博客
WebforEach(): 没有返回值,本质上等同于 for 循环,对每一项执行 function 函数。即map是返回一个新数组,原数组不变,forEach 是不改变原数组(尽管回调函数 callbackFn 在被调用 … WebSep 6, 2014 · QT中foreach的使用. 在标准C++中,并没有foreach关键字。. 但是在QT中,可以使用这一个关键字,其主要原因是QT自己增加了这一个关键字,就像slots和signals、emit等一样。. 增加的foreach关键字在编译时会进行预处理。. 其用法为:. foreach (varItem , Items) // foreach(variable ... fit active storia
c++ - 使用foreach循环嵌套QHash - 堆栈内存溢出
WebNov 13, 2015 · You have to use Q_FOREACH instead of foreach. See the documentation for foreach. That being said, I would switch to the C++11 range-based for, since it doesn't have issues with commas in types. For example, Q_FOREACH (QPair p, pairList) won't compile since the preprocessor thinks you're trying to invoke the macro with 3 arguments ... WebQt的foreach的最大问题是,在遍历之前,它需要复制容器的副本。您可以说"这没关系,因为Qt类被重新计数了",但是因为使用了副本,您实际上根本不会更改原始容器。 总之,Qt … WebAug 29, 2016 · Goodbye, Q_FOREACH A porting guide to C++11 ranged for-loops. Q_FOREACH (or the alternative form, foreach) will be deprecated soon, probably in Qt 5.9. Starting with Qt 5.7, you can use the QT_NO_FOREACH define to make sure that your code does not depend on Q_FOREACH. You may have wondered what all the fuss is about. can fallout 4 be multiplayer