关于vector.push_back

Question

我写了一个程序如下：

trait MyBaseTrait
type MyCP = Boolean :+: Long :+: ... :+: String :+: MyBaseTrait
case class ValidSimple(b: Boolean, s: String) extends MyBaseTrait
case class ValidNested(s: String, vs: ValidSimple) extends MyBaseTrait
case class NotOfBaseTrait(l: Long)

case class InvalidNested(s: String, vs: NotOfBaseTrait) extends MyBaseTrait // => compile error

如果我使用if(i = 0) { vector<int> data; vector<int>::iterator it; data.push_back(2); data.push_back(3); sort(data.begin(),data.end()); it = data.begin(); } if(i = 0) { vector<int> data; vector<int>::iterator it; data.push_back(5); data.push_back(1); sort(data.begin(),data.end()); it = data.begin(); } 两次，它会自动释放吗？我应该释放内存吗？

Answer 1

当变量超出范围时，会自动删除局部变量的内存分配。

if(i == 0)
{
    std::vector<int> data; //local variable
}
//allocation for 'data' is deleted automatically
if(i == 0)
{
    std::vector<int> data; //this is not the same vector as above
    //in fact, the vector above no longer exists at this point
}
//allocation for 'data' is deleted automatically