[英]C++ Vector iterator error
I've been learning C++ for a week, and here is some code I wrote. 我已经学习C ++了一个星期,这是我写的一些代码。 I get an error saying that the vector iterator is out of range. 我收到一个错误,指出向量迭代器超出范围。 The error happens when the value of k
and nZeros
are both 5, possibleGrid[i][j].size()=4
. 当k
和nZeros
的值均为5时,会发生错误, possibleGrid[i][j].size()=4
nZeros
possibleGrid[i][j].size()=4
。
int nZeros = 0;
for (int k = 0; k < Size; k++)
{
if (possibleGrid[i][j][k - nZeros] == 0)
{
nZeros++;
possibleGrid[i][j].erase(possibleGrid[i][j].begin() + k - nZeros); //something here is wrong!!
}
}
You're adding 5 to an iterator that only has 4 valid elements. 您要将5加到仅包含4个有效元素的迭代器中。 The issue here is the order of evaluation. 这里的问题是评估的顺序。 When the compiler sees possibleGrid[i][j].begin() + k - nZeros
, it interprets it as (possibleGrid[i][j].begin() + k) - nZeros
; 当编译器看到possibleGrid[i][j].begin() + k - nZeros
,它将其解释为(possibleGrid[i][j].begin() + k) - nZeros
; thus, when k
and nZeros
are both 5, it first adds 5 to the iterator (rendering it invalid), then subtracts 5 from the now-invalid iterator. 因此,当k
和nZeros
均为5时,它首先将5加到迭代器上(使其无效),然后从现在无效的迭代器中减去5。
To fix the error, just add parentheses around (k - nZeros)
. 要解决该错误,只需在(k - nZeros)
周围加上括号。
I Think if you do below your problem should be solved possibleGrid[i][j].erase(possibleGrid[i][j].begin() + (k - nZeros)); 我认为如果您在下面做您的问题,则应该解决possibleGrid [i] [j] .erase(possibleGrid [i] [j] .begin()+(k-nZeros));
just give a try. 试一试。 :) :)
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