QT foreach keyword

1. brief introduction

foreach Keyword is used to traverse Containers All items in .

foreach yes QtGlobal A macro defined in the header file , Usage is as follows ：

foreach(variable, container)

Use foreach Your code is simpler than using iterators .

2. Examples of use

2.1 Traverse a QLinkedList<QString>
  QLinkedList<QString> list;
  ...
  QString str;
  foreach (str, list)
      qDebug() << str;

2.2 Out of the loop

And anything else c++ Same cycle structure , You can foreach Use curly braces around the loop body , You can use break Get out of the loop .

  QLinkedList<QString> list;
  ...
  foreach (const QString &str, list) {
      if (str.isEmpty())
          break;
      qDebug() << str;
  }

2.3 Traverse QMap keys

 QMap<QString, int> map;
  ...
  foreach (const QString &str, map.keys())
      qDebug() << str << ':' << map.value(str);