在基于范围的 for 循环内从容器中删除元素
我想从当前在基于范围的 for 循环中使用的容器中删除一个元素.这会导致未定义的行为吗?或者,如果我没有调用 erase()
,erase()
之后 element
的下一个值会是下一个元素应该是什么?
I want to erase an element from a container which is being currently used within a ranged-based for loop. Will this cause undefined behaviour? Or will the next value of element
after erase()
be what the next element is supposed to be if I didn't call erase()
?
示例:
std::map<int, int> someMap;
/* Fill in someMap */
for (auto& element : someMap)
{
/* ... */
if ( /* Some condition */ )
someMap.erase(element.first);
}
推荐答案
这应该是一个未定义的行为.因为根据 14882/2011,基于范围的 for 语句等效于:
It should be a undefined behavior. Because according to 14882/2011 the range-based for statement is equivalent to:
auto && __range = range-init;
for ( auto __begin = begin-expr(__range),
__end = end-expr(__range);
__begin != __end;
++__begin ) {
for-range-declaration = *__begin;
statement
}
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