在特殊情况下,双尖括号(>)会产生语法错误 [英] Double closing angle brackets (>>) generate syntax error in SPECIFIC case
问题描述
Eclipse(Luna,4.4.2)告诉我,我在以下一行上有语法错误:
Eclipse (Luna, 4.4.2) tells me that I have a syntax error on the following line:
static_cast<Vec<int, DIM>>(a.mul(b));
我记得双封闭尖括号>>
可能会导致某些编译器出现问题,因此我在两者之间加了一个空格:> >
。语法错误消失。
I remembered that double closing angle brackets >>
can lead to problems with some compilers, so I put a blank in between: > >
. The syntax error disappears.
但是我的程序中有很多>>
,没有检测到语法错误,例如:
BUT I have many >>
in my program where no syntax error is detected, such as:
Node<Element<DIM>> * e= a.get();
为什么在上述特定情况下会出错?这与错误不是重复的:在此未声明 varName范围,因为我要特别问为什么我的编译器有时但不总是接受>>
。
Why do I get an error the above mentioned specific case? This is NOT a duplicate to error: 'varName' was not declared in this scope, since I'm specifically asking why my compiler does accept a >>
sometimes, but not always.
推荐答案
您已使用c ++ 11之前的标准编译器。较早的标准存在一个问题,就是让解析器从 operator>中消除嵌套模板类型说明符中使用的一对闭合尖括号
。因此,您必须在它们之间写一个空格。>>
;>()
You have used a pre c++11 standard compiler. The older standard had a problem letting the parser disambiguate a pair of closing angle brackets >>
used in a nested template type specifier, from the operator>>()
. Thus you had to write a space between them.
像>>>
或<$对于旧的解析器,c $ c>>> * 处于不同的情况下,因此它们可以正常工作而不会出现错误消息。
The samples like >>>
or >>*
are falling under a different case for the old parsers, thus they work without error message.
我必须承认,我实际上不知道在c ++ 11(当前)标准定义中究竟做了什么,这种情况可以通过a清楚地消除。符合c ++ 11的解析器。
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