Usage of vector common interface

repair ： An iterator is a left closed right open interval

vector

Simple understanding vector Is a sequence container that represents a variable size array

vector Use

One 、vector The definition of

	//1
	vector<int> arr1;
	//3
	vector<int> arr3(arr2);
	//2
	vector<int> arr4(5,0);
	//4  This is implemented using iterators 
	string std("hello");
	vector<char> ch1(std.begin(), std.end());
	//5  It can also be initialized like this, but C++98 This is not supported 
	vector<int> arr2 = { 1,2,3,4,5 };

Two 、vector iterator Use

	// Then, as defined above ch1 and arr3   
	// If you don't want to write so long, you can also use auto Automatic derivation 
	//for (auto it = ch1.begin(); it != ch1.end(); ++it)
	for (vector<char>::iterator it = ch1.begin(); it != ch1.end(); ++it)
	{
		cout << *it << " ";
	}
	cout << endl;
	//for (auto it = arr3.rbegin(); it != arr3.rend(); ++it)
	for (vector<int>::reverse_iterator it = arr3.rbegin(); it != arr3.rend(); ++it)
	{
		cout << *it << " ";
	}
	cout << endl;

3、 ... and 、vector Spatial growth

• capacity Code in vs and g++ The growth of is different ,vs Next capacity Is in accordance with the 1.5 Multiplied by ,g++ Is in accordance with the 2 Multiplied by (vs yes PJ Version of STL,g++ yes SGI Version of STL)

• reserve Only responsible for opening up space , If you're sure you know how much space you need ,reserve Can ease vector The cost of capacity expansion is flawed

• resize In the open space at the same time also will carry on the initialization , It will affect size

• resize If appear size Smaller than the original situation , Although it won't reduce the space, it will change size
  

Four 、vector Add or delete check change

	vector<int>arr1;
	// Tail insert a data 
	arr1.push_back(1);
	arr1.push_back(2);
	arr1.push_back(3);
	arr1.push_back(4);
	arr1.push_back(5);
	// Use iterators to traverse 
	for (vector<int>::iterator it = arr1.begin(); it != arr1.end(); ++it)
	{
		cout << *it << " ";
	}
	cout << endl;
	// On the left is the iterator , On the right is the data to be inserted 
	arr1.insert(arr1.begin() + 3, 6);
	arr1.insert(arr1.begin() + 3, 7);
	for (vector<int>::iterator it = arr1.begin(); it != arr1.end(); ++it)
	{
		cout << *it << " ";
	}
	cout << endl;
	// Delete a data at the end , Call directly without parameters 
	arr1.pop_back();
	arr1.pop_back();
	for (vector<int>::iterator it = arr1.begin(); it != arr1.end(); ++it)
	{
		cout << *it << " ";
	}
	cout << endl;
	// The iterator passes the position 
	arr1.erase(arr1.end()-2);
	for (vector<int>::iterator it = arr1.begin(); it != arr1.end(); ++it)
	{
		cout << *it << " ";
	}
	cout << endl;
	vector<int> arr2;
	// In exchange for 
	swap(arr1, arr2);
	swap(arr2[0], arr2[3]);

	for (vector<int>::iterator it = arr1.begin(); it != arr1.end(); ++it)
	{
		cout << *it << " ";
	}
	cout << endl;
	for (vector<int>::iterator it = arr2.begin(); it != arr2.end(); ++it)
	{
		cout << *it << " ";
	}
	cout << endl;
	arr1 = { 9,8,7,6,5 };
	for (vector<int>::iterator it = arr1.begin(); it != arr1.end(); ++it)
	{
		cout << *it << " ";
	}
	cout << endl;
	// Empty data 
	arr1.clear();
	for (vector<int>::iterator it = arr1.begin(); it != arr1.end(); ++it)
	{
		cout << *it << " ";
	}
	cout << endl;

	vector<int>arr1 = { 9,8,7,6,5 };
	vector<int>arr2 = { 0,1,2,3,4,10,11,12 };
	// By iterator , You can give arr1 Assign data to other objects 
	// If the assigned object is larger than the original object , It will be automatically expanded to... With large objects capacity identical 
	arr1.assign(arr2.begin(), arr2.end());
	for (vector<int>::iterator it = arr1.begin(); it != arr1.end(); ++it)
	{
		cout << *it << " ";
	}
	cout << endl;
	// On the left is a number , On the right is the value , It's just Fu 8 individual 0
	arr1.assign(8, 0);
	for (vector<int>::iterator it = arr1.begin(); it != arr1.end(); ++it)
	{
		cout << *it << " ";
	}
	cout << endl;

	//find No vector Member interface of , It's in the algorithm library , Must include header file when using  #include<algorithm>
	vector<int>arr1 = {
     1,2,3,4,5,6,7,8 };
	//find The first two parameters pass an iterator interval , The third parameter is the data to be searched 
	// If it can be found, it returns the iterator that finds the data location , If you can't find it, go back end(), So judge 
	vector<int>::iterator it=find(arr1.begin(), arr1.end(),9);
	if (it != arr1.end())
	{
    
		cout << *it << endl;
	}