<分区>
我正在研究迭代器，并在弄清楚我们为什么使用迭代器上卡住了 3 天:
auto mid = text.begin() + (end - beg) / 2;
代码:
int main()
{
vector<int> text{ 10,9,8,7,6,5,4,3,2,1 };
int sought = 3;
// text must be sorted
// beg and end will denote the range we're searching
auto beg = text.begin(), end = text.end();
auto mid = text.begin() + (end - beg) / 2; // original midpoint
// while there are still elements to look at and we haven't yet found sought
while (mid != end && *mid != sought) {
if (sought < *mid) // is the element we want in the first half?
end = mid; // if so, adjust the range to ignore the second half
else // the element we want is in the second half
beg = mid + 1; // start looking with the element just after mid
mid = beg + (end - beg) / 2;// new midpoint
}
system("pause");
}
为什么
auto mid = text.begin() + (end - beg) / 2;
而不是:
auto mid = text.begin() + text.size() / 2;
请帮忙。