从动态数组复制到C ++中的动态数组

Question

I have a array whose size is determined in runtime.

cout<<"Enter size of array: ";
cin>>size1;
int* scores=new int[size1];

Then I fill up this array scores. Now I want to increase its size. I create a new dynamic array.

int* newScores=new int[newSize1];  
such that `newSize1 > Size1

Now I copy content of old scores into newScores:

for(int i=0; i<Size1;i++)
{newScores[i] = scores[i];
}

Now I have to ask remaining element of newScores to add to it. I did:

for(int j=size1;j<newSize1;j++)
{
newScores[j]=new int;
cout<<"Enter new score: ";
cin>>newScores[j];
}

While I compile it, I get the above error:
error: invalid conversion from 'int*' to 'int' [-fpermissive] newScores[size1]=new int;

Answer 1

newScores[j]=new int; is an error, and not necessary. newscores[j] is a lvlalue int , while new int returns int* . But you already have no need to allocate it - you did it in the int* newScores=new int[newSize1]; expression.

You could avoid the thole hassle by using std::vector<int> . It resizes itself automatically as you insert elements into it (with push_back ), and you don't have to worry about releasing the memory yourself.

Answer 2

删除此行

newScores[j]=new int;

Answer 3

You do not need to assign new int to your dynamic array again. Besides, you need to delete the memory by using delete[] when you use dynamic array