为什么我得到“向量迭代器不兼容”? [英] Why am I getting "vector iterators incompatible"?
问题描述
为什么这段代码
#include< algorithm>
#include< iterator>
#include< vector>
int main()
{
std :: vector< int> v;
v.push_back(1);
v.push_back(2);
v.push_back(3);
v.reserve(v.size()* 2); //保留足够的空间来保持迭代器有效
std :: copy(v.begin(),v.end(),std :: back_inserter(v));
return 0;
}
给我调试断言失败表达式:vector iterators incompatible (Visual C ++ 2008)?
对应于元素的迭代器只有在向量必须重新分配时才会失效 reserve
避免。
但是, v.end()
push_back 和 insert
保证
如果新大小大于旧容量,则导致重新分配。如果没有重新分配,
插入点之前的所有迭代器和引用仍然有效。
v.end()
不是插入点之前。
Why does this code
#include <algorithm>
#include <iterator>
#include <vector>
int main()
{
std::vector<int> v;
v.push_back(1);
v.push_back(2);
v.push_back(3);
v.reserve(v.size() * 2); // Reserve enough space to keep iterators valid
std::copy(v.begin(), v.end(), std::back_inserter(v));
return 0;
}
give me the debug assertion failure, Expression: vector iterators incompatible (Visual C++ 2008)?
解决方案 Iterators corresponding to elements are only invalidated when the vector has to be reallocated, which reserve
avoids.
However, v.end()
won't stay valid.
The Standard's description of push_back
and insert
guarantees that
Causes reallocation if the new size is greater than the old capacity. If no reallocation happens,
all the iterators and references before the insertion point remain valid.
v.end()
is not "before the insertion point".
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