任务是实现一个类似于 STL 向量的自定义向量类，具有以下功能：
- int push_back(data)：将一个元素(任何数据类型)添加到数组的末尾，并返回该向量中的元素数
- data_type pop_back()：从数组末尾移除一个元素，同时返回被弹出的元素
- int size() const：返回向量的当前大小
下面的程序在 C++ 中实现了一个具有上述功能的自定义向量类：
CPP14
// C++ program to implement Custom Vector
// class
#include "iostream"
#define ll long long
using namespace std;
// Template class to create vector of
// different data_type
template
class GenericMyVector {
private:
DT* arr;
// Variable to store the current capacity
// of the vector
ll capacity;
// Variable to store the length of the
// vector
ll length;
public:
explicit GenericMyVector(ll = 100);
// Function that returns the number of
// elements in array after pushing the data
ll push_back(DT);
// function that returns the popped element
DT pop_back();
// Function that return the size of vector
ll size() const;
DT& operator[](ll);
// Iterator Class
class iterator {
private:
// Dynamic array using pointers
DT* ptr;
public:
explicit iterator()
: ptr(nullptr)
{
}
explicit iterator(DT* p)
: ptr(p)
{
}
bool operator==(const iterator& rhs) const
{
return ptr == rhs.ptr;
}
bool operator!=(const iterator& rhs) const
{
return !(*this == rhs);
}
DT operator*() const
{
return *ptr;
}
iterator& operator++()
{
++ptr;
return *this;
}
iterator operator++(int)
{
iterator temp(*this);
++*this;
return temp;
}
};
// Begin iterator
iterator begin() const;
// End iterator
iterator end() const;
};
// Template class to return the size of
// vector of different data_type
template
GenericMyVector::GenericMyVector(ll n)
: capacity(n), arr(new DT[n]), length(0)
{
}
// Template class to insert the element
// in vector
template
ll GenericMyVector::push_back(DT data)
{
if (length == capacity) {
DT* old = arr;
arr = new DT[capacity = capacity * 2];
copy(old, old + length, arr);
delete[] old;
}
arr[length++] = data;
return length;
}
// Template class to return the popped element
// in vector
template
DT GenericMyVector::pop_back()
{
return arr[length-- - 1];
}
// Template class to return the size of
// vector
template
ll GenericMyVector::size() const
{
return length;
}
// Template class to return the element of
// vector at given index
template
DT& GenericMyVector::operator[](ll index)
{
// if given index is greater than the
// size of vector print Error
if (index >= length) {
cout << "Error: Array index out of bound";
exit(0);
}
// else return value at that index
return *(arr + index);
}
// Template class to return begin iterator
template
typename GenericMyVector::iterator
GenericMyVector::begin() const
{
return iterator(arr);
}
// Template class to return end iterator
template
typename GenericMyVector::iterator
GenericMyVector::end() const
{
return iterator(arr + length);
}
// Template class to display element in
// vector
template
void display_vector(V& v)
{
// Declare iterator
typename V::iterator ptr;
for (ptr = v.begin(); ptr != v.end(); ptr++) {
cout << *ptr << ' ';
}
cout << '\n';
}
// Driver code
int main()
{
cout << "For Integer data_type" << endl;
GenericMyVector v;
v.push_back(5);
v.push_back(6);
v.push_back(7);
v.push_back(8);
v.push_back(9);
v.push_back(10);
v.push_back(11);
v.push_back(12);
// Declare iterator for traversal in
// vector v
GenericMyVector::iterator it;
// Function called to display element in
// vector in v
cout << "Element in vector v : ";
display_vector(v);
// Print the size of vector v
cout << "size: " << v.size() << endl;
// Print Element at index 2
cout << "v[2]: " << v[2] << '\n';
// Pop an element and print it
cout << "Popped Element: " << v.pop_back() << '\n';
display_vector(v);
cout << endl;
cout << "For Char data_type" << endl;
GenericMyVector c;
c.push_back('a');
c.push_back('b');
c.push_back('c');
c.push_back('d');
c.push_back('e');
c.push_back('f');
c.push_back('g');
c.push_back('h');
// Declare iterator for traversal in
// vector c
GenericMyVector::iterator it1;
// Function called to display element in
// vector in c
cout << "Element in vector c : ";
display_vector(c);
// Print the size of vector c
cout << "size: " << c.size() << '\n';
// Print Element at index 2
cout << "c[2]: " << c[2] << '\n';
// Pop an element and print it
cout << "pop: " << c.pop_back() << '\n';
// Function called to display element in
// vector in c
cout << "Element in vector c : ";
display_vector(c);
return 0;
} 输出：
For Integer data_type
Element in vector v : 5 6 7 8 9 10 11 12
size: 8
v[2]: 7
Popped Element: 12
5 6 7 8 9 10 11
For Char data_type
Element in vector c : a b c d e f g h
size: 8
c[2]: c
pop: h
Element in vector c : a b c d e f g想要从精选的视频和练习题中学习，请查看C++ 基础课程，从基础到高级 C++ 和C++ STL 课程，了解语言和 STL。要完成从学习语言到 DS Algo 等的准备工作，请参阅完整的面试准备课程。