个人如何在企业网站做实名认证,如何在微信创建公众号,网站栏目页 优化,营销型网站建设标准C自学精简教程 目录(必读)
该 Vector 版本特点
这里的版本主要是使用模板实现、支持随机访问迭代器#xff0c;支持std::sort等所有STL算法。(本文对随机迭代器的支持参考了 复旦大学 大一公共基础课C语言的一次作业)
随机访问迭代器的实现主要是继承std::iteratorstd:…C自学精简教程 目录(必读)
该 Vector 版本特点
这里的版本主要是使用模板实现、支持随机访问迭代器支持std::sort等所有STL算法。(本文对随机迭代器的支持参考了 复旦大学 大一公共基础课C语言的一次作业)
随机访问迭代器的实现主要是继承std::iteratorstd::random_access_iterator_tag, T来实现的。
随机访问迭代器最牛逼的两个接口是
friend iterator operator(const iterator lhs, size_t n);
friend iterator operator-(const iterator lhs, size_t n);
问题解答
1 为何下面代码中的iterator是struct而不是class
答参考struct与class
题目代码
头文件 Vector.h
#ifndef VEC_H
#define VEC_H
#include iostream
#include cassert
#include initializer_list
//------下面的代码是用来测试你的代码有没有问题的辅助代码你无需关注------
#include algorithm
#include cstdlib
#include iostream
#include vector
#include utility
using namespace std;
struct Record { Record(void* ptr1, size_t count1, const char* location1, int line1, bool is) :ptr(ptr1), count(count1), line(line1), is_array(is) { int i 0; while ((location[i] location1[i]) i 100) { i; } }void* ptr; size_t count; char location[100] { 0 }; int line; bool is_array false; bool not_use_right_delete false; }; bool operator(const Record lhs, const Record rhs) { return lhs.ptr rhs.ptr; }std::vectorRecord myAllocStatistic; void* newFunctionImpl(std::size_t sz, char const* file, int line, bool is) { void* ptr std::malloc(sz); myAllocStatistic.push_back({ ptr,sz, file, line , is }); return ptr; }void* operator new(std::size_t sz, char const* file, int line) { return newFunctionImpl(sz, file, line, false); }void* operator new [](std::size_t sz, char const* file, int line)
{return newFunctionImpl(sz, file, line, true);
}void operator delete(void* ptr) noexcept { Record item{ ptr, 0, , 0, false }; auto itr std::find(myAllocStatistic.begin(), myAllocStatistic.end(), item); if (itr ! myAllocStatistic.end()) { auto ind std::distance(myAllocStatistic.begin(), itr); myAllocStatistic[ind].ptr nullptr; if (itr-is_array) { myAllocStatistic[ind].not_use_right_delete true; } else { myAllocStatistic[ind].count 0; }std::free(ptr); } }void operator delete[](void* ptr) noexcept { Record item{ ptr, 0, , 0, true }; auto itr std::find(myAllocStatistic.begin(), myAllocStatistic.end(), item); if (itr ! myAllocStatistic.end()) { auto ind std::distance(myAllocStatistic.begin(), itr); myAllocStatistic[ind].ptr nullptr; if (!itr-is_array) { myAllocStatistic[ind].not_use_right_delete true; } else { myAllocStatistic[ind].count 0; }std::free(ptr); } }
#define new new(__FILE__, __LINE__)
struct MyStruct { void ReportMemoryLeak() { std::cout Memory leak report: std::endl; bool leak false; for (auto i : myAllocStatistic) { if (i.count ! 0) { leak true; std::cout leak count i.count Byte , file i.location , line i.line; if (i.not_use_right_delete) { cout , not use right delete. ; } cout std::endl; } }if (!leak) { cout No memory leak. endl; } }~MyStruct() { ReportMemoryLeak(); } }; static MyStruct my; void check_do(bool b, int line __LINE__) { if (b) { cout line: line Pass endl; } else { cout line: line Ohh! not passed!!!!!!!!!!!!!!!!!!!!!!!!!!! endl; exit(0); } }
#define check(msg) check_do(msg, __LINE__);
//------上面的代码是用来测试你的代码有没有问题的辅助代码你无需关注------templatetypename T
class Vector
{
public:/* 提供默认构造函数 否则只能使用有参版本这会带来不变例如Vectorint arr; 这样会报错因为需要默认构造函数*/Vector(void);//如果类提供了非默认构造函数编译器不会自动提供默认构造函数Vector(const Vector from);// 复制构造函数Vector(T* start, T* end);// 非默认构造函数Vector(int count, int value);//2 非默认构造函数Vector(std::initializer_listT value_array){for (auto item : value_array){push_back(item);}}Vector operator (const Vector from);bool operator(const Vector other) const{//(1) your codereturn false;}//赋值操作符~Vector();//析构函数
public:size_t size(void) const;bool empty(void) const;T operator[] (size_t n) const;T operator[] (size_t n);void push_back(const T val);void clear(void);
private:void deep_copy_from(const VectorT from);public:struct iterator : std::iteratorstd::random_access_iterator_tag, T{friend class Vector;friend bool operator (const iterator lhs, const iterator rhs) { return lhs.m_hold rhs.m_hold; }friend bool operator ! (const iterator lhs, const iterator rhs) { return !(lhs rhs); }friend size_t operator - (const iterator lhs, const iterator rhs) { return lhs.m_hold - rhs.m_hold; }friend bool operator (const iterator lhs, const iterator rhs) { return lhs.m_hold rhs.m_hold; }friend bool operator (const iterator lhs, const iterator rhs) { return lhs.m_hold rhs.m_hold; }friend bool operator (const iterator lhs, const iterator rhs) { return !(lhs rhs); }friend bool operator (const iterator lhs, const iterator rhs) { return !(lhs rhs); }friend iterator operator (const iterator lhs, size_t n) { iterator itr; itr.m_hold lhs.m_hold n; return itr; }//随机访问迭代器牛逼的地方friend iterator operator - (const iterator lhs, size_t n) { iterator itr; itr.m_hold lhs.m_hold - n; return itr; }//随机访问迭代器牛逼的地方public://用于前置形式iterator operator() { m_hold m_hold 1; return *this; };iterator operator--() { m_hold m_hold - 1; return *this; };//用于后置形式iterator operator(int) { iterator itr *this; m_hold 1; return itr; }iterator operator--(int) { iterator itr *this; m_hold - 1; return itr; }T operator*() const//这里必须是const in C14{return *m_hold;}private:T* m_hold;};struct const_iterator : std::iteratorstd::random_access_iterator_tag, T{friend class Vector;friend bool operator (const const_iterator lhs, const const_iterator rhs) { return lhs.m_hold rhs.m_hold; }friend bool operator ! (const const_iterator lhs, const const_iterator rhs) { return !(lhs rhs); }friend size_t operator - (const const_iterator lhs, const const_iterator rhs) { return lhs.m_hold - rhs.m_hold; }friend bool operator (const const_iterator lhs, const const_iterator rhs) { return lhs.m_hold rhs.m_hold; }friend bool operator (const const_iterator lhs, const const_iterator rhs) { return lhs.m_hold rhs.m_hold; }friend bool operator (const const_iterator lhs, const const_iterator rhs) { return !(lhs rhs); }friend bool operator (const const_iterator lhs, const const_iterator rhs) { return !(lhs rhs); }friend const_iterator operator (const const_iterator lhs, size_t n) { const_iterator itr; itr.m_hold lhs.m_hold n; return itr; }//随机访问迭代器牛逼的地方friend const_iterator operator - (const const_iterator lhs, size_t n) { const_iterator itr; itr.m_hold lhs.m_hold - n; return itr; }//随机访问迭代器牛逼的地方public://用于前置形式const_iterator operator() { m_hold m_hold 1; return *this; };const_iterator operator--() { m_hold m_hold - 1; return *this; };//用于后置形式const_iterator operator(int) { const_iterator itr *this; m_hold 1; return itr; }const_iterator operator--(int) { const_iterator itr *this; m_hold - 1; return itr; }const T operator*() const{return *m_hold;}private:T* m_hold;};iterator begin() noexcept{iterator itr;itr.m_hold empty() ? nullptr : m_data[0];return itr;}const_iterator cbegin() const noexcept;iterator end() noexcept{iterator itr;itr.m_hold empty() ? nullptr : m_data[m_size];return itr;}const_iterator cend() const noexcept;
private:size_t m_size 0;//当前元素数量size_t m_capacity 0;//容量T* m_data nullptr;//数据部分
};templatetypename T
VectorT::Vector(void)
{
}templatetypename T
VectorT::Vector(T * start, T * end)
{std::cout Vector(T* start, T* end) std::endl;assert(start ! nullptr end ! nullptr);m_capacity m_size ((size_t)end - (size_t)start)/sizeof(T);//这里如果用int来存放可能会盛不下size_t可以保证盛放的下assert(m_size 0);m_data new T[m_size];for (size_t i 0; i m_size; i){m_data[i] *start;}
}
templatetypename T
VectorT::Vector(int count, int value)
{std::cout Vector(count, value) std::endl;if (count 0){throw std::runtime_error(size of vector to init must bigger than zero!);}m_data new T[count];for (size_t i 0; i count; i){m_data[i] value;}m_capacity m_size count;
}
templatetypename T
VectorT VectorT::operator(const VectorT from)
{std::cout Vector::operator std::endl;if (this from){return *this;}//先释放自己的数据clear();deep_copy_from(from);return *this;
}templatetypename T
VectorT::~Vector()
{//(2) your code}
templatetypename T
size_t VectorT::size(void) const
{return m_size;
}
templatetypename T
bool VectorT::empty(void) const
{//(3) your codereturn false;//此处需要修改。
}
templatetypename T
T VectorT::operator[](size_t n) const
{//(4) your codestatic T t;//此处需要修改。return t;//此处需要修改。
}
templatetypename T
T VectorT::operator[](size_t n)
{//(4) your codestatic T t;//此处需要修改。return t;//此处需要修改。
}
templatetypename T
void VectorT::push_back(const T val)
{//(5) your code// 这里需要考虑第一次插入数据的时候还没有开辟任何动态空间的情况因为构造函数不再负责事先开辟好少量的初始预留空间了
}templatetypename T
void VectorT::clear(void)
{//(6) your code
}templatetypename T
void VectorT::deep_copy_from(const VectorT from)
{//(7) your code}templatetypename T
VectorT::Vector(const Vector from)
{//(8) your code}templatetypename T
typename VectorT::const_iterator VectorT::cend() const noexcept
{VectorT::const_iterator itr;//(9) your codereturn itr;
}templatetypename T
typename VectorT::const_iterator VectorT::cbegin() const noexcept
{const_iterator itr;//(10) your codereturn itr;
}#endif测试代码main.cpp
#include iostream
#include algorithm
#include Vector.h
#include vectortemplatetypename T
void print(const VectorT v, const std::string msg)
{std::cout The contents of msg.c_str() are:;for (int i 0; i v.size(); i){std::cout v[i];}std::cout \n;
}
templatetypename T
void print_itr(VectorT v, const std::string msg)
{std::cout The contents of msg.c_str() are:;for (auto itr v.begin(); itr ! v.end(); itr){std::cout *itr;}std::cout \n;
}
templatetypename T
void print_const_itr(const VectorT v, const std::string msg)
{std::cout The contents of msg.c_str() are:;for (auto itr v.cbegin(); itr ! v.cend(); itr){std::cout *itr;}std::cout \n;
}int main()
{Vectorint a;Vectorint first; // empty vector of intscheck(first.empty() true first.size() 0);Vectorint second(4, 100); // four ints with value 100check(second.empty() false);check(second.size() 4);check(*second.begin() 100);Vectorint fourth(second); // a copy of thirdcheck(fourth.size() second.size());int myints[] { 16,2,77,29 };Vectorint fifth(myints, myints sizeof(myints) / sizeof(int));check(fifth.empty() false);check(fifth[0] 16);check(fifth[3] 29);check(fifth.size() sizeof(myints) / sizeof(int));print(fifth, fifth);//The contents of fifth are:16 2 77 29 fifth.push_back(30);check(fifth[4] 30);check(fifth.size() 5);print(fifth, fifth);//The contents of fifth are:16 2 77 29 30 check(fifth.size() sizeof(myints) / sizeof(int) 1);first fifth fifth;print(first, first);//The contents of first are:16 2 77 29 30 check(first.empty() false first.size() fifth.size());print_itr(fifth, fifth);//The contents of fifth are:16 2 77 29 30 print_const_itr(fifth, fifth);//The contents of fifth are:16 2 77 29 30 std::sort(fifth.begin(), fifth.end());std::cout fifith after sort: std::endl;print_const_itr(fifth, fifth);//The contents of fifth are:16 2 77 29 30 Vectorint a1(myints, myints sizeof(myints) / sizeof(int));{Vectorint b(a1);b.push_back(2);check(b[4] 2);auto result (b Vectorint{ 16, 2, 77, 29, 2});check(result);//iteratorcheck(b.begin() b.size() b.end());auto begin b.begin();auto itr b.begin() 1;check(*begin 16);check(*itr 2);}{Vectorint b{ 1,3,5,7 };b.push_back(9);}{Vectorint c;for (auto i : c){std::cout i ;}c a1;for (auto i : c){std::cout i ;}std::cout std::endl;}check(a1.size() sizeof(myints) / sizeof(int));{Vectorint c;c fifth;c[0] 1;check(c[0] 1);}
}预期输出
line:42 Pass
Vector(count, value)
line:44 Pass
line:45 Pass
line:46 Pass
line:48 Pass
Vector(T* start, T* end)
line:52 Pass
line:53 Pass
line:54 Pass
line:55 Pass
The contents of fifth are: 16 2 77 29
line:58 Pass
line:59 Pass
The contents of fifth are: 16 2 77 29 30
line:61 Pass
Vector::operator
Vector::operator
The contents of first are: 16 2 77 29 30
line:64 Pass
The contents of fifth are: 16 2 77 29 30
The contents of fifth are: 16 2 77 29 30
fifith after sort:
The contents of fifth are: 2 16 29 30 77
Vector(T* start, T* end)
line:74 Pass
line:76 Pass
Vector::operator
16 2 77 29
line:95 Pass
Vector::operator
line:100 Pass
Memory leak report:
No memory leak.
