foreach用法c语言,QT中foreach()的使用方法

foreach()

​foreach(变量,容器)

​在qt中foreach是一个关键字 ,类似于c语言的for循环

​原文:

​The foreach Keyword

​If you just want to iterate over all the items in a container in order, you can use Qt's foreach keyword. The keyword is a Qt-specific addition to the C++ language, and is implemented using the preprocessor.

​Its syntax is: foreach (variable, container) statement. For example, here's how to use foreach to iterate over a QLinkedList:

​翻译:

如果您只是想遍历容器中的所有条目,那么您可以使用Qt的foreach关键字。关键字是对C++语言的一个特定于qt的添加,并且是使用预处理程序实现的。

它的语法是:foreach(变量,容器)语句。例如,下面是如何使用foreach来迭代QLinkedList:

​QLinkedList list;

...

QString str;

foreach (str, list)

qDebug() << str;

​原文:The foreach code is significantly shorter than the equivalent code that uses iterators:

​翻译:foreach代码比使用迭代器的等效代码要短得多:

​QLinkedList list;

...

QLinkedListIterator i(list);

while (i.hasNext())

qDebug() << i.next();

​原文:Unless the data type contains a comma (e.g., QPair), the variable used for iteration can be defined within the foreach statement:

​翻译:除非数据类型包含一个逗号(例如,QPair

​QLinkedList list;

...

foreach (const QString &str, list)

qDebug() << str;

​原文:And like any other C++ loop construct, you can use braces around the body of a foreach loop, and you can use break to leave the loop:

​翻译:就像任何其他C++循环结构一样,您可以在foreach循环的主体周围使用牙套,您可以使用break来离开循环:

​QLinkedList list;

...

foreach (const QString &str, list) {

if (str.isEmpty())

break;

qDebug() << str;

}

​例子:QStringList slt = {"abc", "qwe", "upo"};foreach(QString s , slt )

{

cout<

}//输出结果为:abc

qwe

upo

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