vector <vector<int> > v8;
int N;
cin >> N;
for (int i = 0; i < N; i )
{
int n;
cin >> n;
vector <int> temp;
for (int i = 0; i < n; i )
{
int x;
cin >> x;
temp.push_back(x);
}
v8.push_back(temp);
}
vector <int> ::iterator it;
for (it = v8.begin(); it < v8.end(); it )
{
cout << (*it) << " ";
}
我收到此錯誤：
no operator "=" matches these operandsC/C (349)
intro.cpp(161, 13): operand types are: __gnu_cxx::__normal_iterator<int *, std::vector<int, std::allocator<int>>> = __gnu_cxx::__normal_iterator<std::vector<int, std::allocator<int>> *, std::vector<std::vector<int, std::allocator<int>>, std::allocator<std::vector<int, std::allocator<int>>>>>
我該怎么解決這個問題？？
uj5u.com熱心網友回復：
問題是它it是1D的迭代器vector<int>，而b8.begin()給我們提供了 2D 的迭代器vector<vector<int>>。所以這些迭代器彼此不兼容。也就是說，您不能使用迭代器it來遍歷二維向量。
vector <int> ::iterator it;您可以通過如下所示進行更改來解決此問題：
vector <vector<int>> ::iterator it; //change made here. Now it is an iterator to a 2D vector
for (it = v8.begin(); it != v8.end(); it )
{
for(auto i = (*it).begin(); i != (*it).end(); i) // i is an iterator to a 1D vector
{
cout << (*i) << " ";//it changed to i
}
}
另一種選擇是使用auto基于范圍的for回圈，如下所示：
for (auto &row: v8)
{
for(auto &col: row)
{
cout << col << " ";
}
}
uj5u.com熱心網友回復：
要遍歷 中的向量v8，列舉它們的元素，請使用基于范圍的for回圈。
for (auto& v: v8) {
for (auto& it: v) {
std::cout << it << ' ';
}
}
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