Qt文档里面这么描述的(至于定义,应该翻源码吧)
foreach ( variable, container )
This macro is used to implement Qt's foreach loop. The variable parameter is a variable name or variable definition; the container parameter is a Qt container whose value type corresponds to the type of the variable. See The foreach Keyword for details.
If you're worried about namespace pollution, you can disable this macro by adding the following line to your .pro file:
CONFIG += no_keywords
See also Q_FOREACH().