问题描述
据说，临时变量是评估完整表达式的最后一步，例如
It is said that temporary variables are destroyed as the last step in evaluating the full-expression, e.g.
bar( foo().c_str() );
临时指针一直存在，直到bar返回，但是对于
temporary pointer lives until bar returns, but what for the
baz( bar( foo().c_str() ) );
它仍然存在，直到bar返回，或者baz return表示此处已完全表达，baz返回后我检查了销毁对象的编译器，但是我可以依靠它吗?
is it still lives until bar returns, or baz return means full-expression end here,compilers I checked destruct objects after baz returns, but can I rely on that?
推荐答案
临时生命，直到创建它们的完整表达式的结尾. 完整表达式"是不是另一个表达式的子表达式的表达式.
Temporaries life until the end of the full expression in which they are created. A "full expression" is an expression that's not a sub-expression of another expression.
在baz(bar(...));中，bar(...)是baz(...)的子表达式，而baz(...)不是任何东西的子表达式.因此，baz(...)是完整表达式，并且在返回baz(...)之后，将不删除此表达式求值过程中创建的所有临时对象.
In baz(bar(...));, bar(...) is a subexpression of baz(...), while baz(...) is not a subexpression of anything. Therefore, baz(...) is the full expression, and all temporaries created during the evaluation of this expression will not be deleted until after baz(...) returned.
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