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网站建设seo优化浙江,电商网站搜索引擎怎么做,简述网络推广5种方法,网站论坛源码文章目录 练习14.21练习14.22头文件CPP文件 练习14.23头文件CPP文件 练习14.24头文件CPP文件 练习14.25练习14.26练习14.27练习14.28练习14.29练习14.30 练习14.21 编写 Sales_data 类的 和 运算符#xff0c;使得 执行实际的加法操作而 调用。相比14.3节和14.4节对这两个运… 文章目录 练习14.21练习14.22头文件CPP文件 练习14.23头文件CPP文件 练习14.24头文件CPP文件 练习14.25练习14.26练习14.27练习14.28练习14.29练习14.30 练习14.21 编写 Sales_data 类的 和 运算符使得 执行实际的加法操作而 调用。相比14.3节和14.4节对这两个运算符的定义本题的定义有何缺点试讨论之。 缺点使用了一个 Sales_data 的临时对象但它并不是必须的。 练习14.22 定义赋值运算符的一个新版本使得我们能把一个表示 ISBN 的 string 赋给一个 Sales_data 对象。 头文件 #ifndef CP5_ex14_22_h #define CP5_ex14_22_h#include string #include iostreamclass Sales_data {friend std::istream operator(std::istream, Sales_data);friend std::ostream operator(std::ostream, const Sales_data);friend Sales_data operator(const Sales_data, const Sales_data);public:Sales_data(const std::string s, unsigned n, double p) :bookNo(s), units_sold(n), revenue(n*p) {}Sales_data() : Sales_data(, 0, 0.0f) {}Sales_data(const std::string s) : Sales_data(s, 0, 0.0f) {}Sales_data(std::istream is);Sales_data operator(const std::string);Sales_data operator(const Sales_data);std::string isbn() const { return bookNo; }private:inline double avg_price() const;std::string bookNo;unsigned units_sold 0;double revenue 0.0; };std::istream operator(std::istream, Sales_data); std::ostream operator(std::ostream, const Sales_data); Sales_data operator(const Sales_data, const Sales_data);inline double Sales_data::avg_price() const {return units_sold ? revenue / units_sold : 0; }#endifCPP文件 #include exercise14_22.hSales_data::Sales_data(std::istream is) : Sales_data() {is *this; }Sales_data Sales_data::operator(const Sales_data rhs) {units_sold rhs.units_sold;revenue rhs.revenue;return *this; }std::istream operator(std::istream is, Sales_data item) {double price 0.0;is item.bookNo item.units_sold price;if (is)item.revenue price * item.units_sold;elseitem Sales_data();return is; }std::ostream operator(std::ostream os, const Sales_data item) {os item.isbn() item.units_sold item.revenue item.avg_price();return os; }Sales_data operator(const Sales_data lhs, const Sales_data rhs) {Sales_data sum lhs;sum rhs;return sum; }Sales_data Sales_data::operator(const std::string isbn) {*this Sales_data(isbn);return *this; }练习14.23 为你的StrVec 类定义一个 initializer_list 赋值运算符。 头文件 #ifndef CP5_STRVECH #define CP5_STRVECH#include memory #include string #include initializer_list#ifndef _MSC_VER #define NOEXCEPT noexcept #else #define NOEXCEPT #endifclass StrVec {friend bool operator(const StrVec, const StrVec);friend bool operator!(const StrVec, const StrVec);friend bool operator (const StrVec, const StrVec);friend bool operator (const StrVec, const StrVec);friend bool operator(const StrVec, const StrVec);friend bool operator(const StrVec, const StrVec);public:StrVec() : elements(nullptr), first_free(nullptr), cap(nullptr) {}StrVec(std::initializer_liststd::string);StrVec(const StrVec);StrVec operator(const StrVec);StrVec(StrVec) NOEXCEPT;StrVec operator(StrVec)NOEXCEPT;~StrVec();StrVec operator(std::initializer_liststd::string);void push_back(const std::string);size_t size() const { return first_free - elements; }size_t capacity() const { return cap - elements; }std::string *begin() const { return elements; }std::string *end() const { return first_free; }std::string at(size_t pos) { return *(elements pos); }const std::string at(size_t pos) const { return (elements pos); }void reserve(size_t new_cap);void resize(size_t count);void resize(size_t count, const std::string);private:std::pairstd::string, std::string* alloc_n_copy(const std::string, const std::string);void free();void chk_n_alloc() { if (size() capacity()) reallocate(); }void reallocate();void alloc_n_move(size_t new_cap);void range_initialize(const std::string, const std::string);private:std::string *elements;std::string *first_free;std::string cap;std::allocatorstd::string alloc; };bool operator(const StrVec, const StrVec); bool operator!(const StrVec, const StrVec); bool operator (const StrVec, const StrVec); bool operator (const StrVec, const StrVec); bool operator(const StrVec, const StrVec); bool operator(const StrVec, const StrVec);#endifCPP文件 #include exercise14_23.h #include algorithmvoid StrVec::push_back(const std::string s) {chk_n_alloc();alloc.construct(first_free, s); }std::pairstd::string, std::string* StrVec::alloc_n_copy(const std::string *b, const std::string *e) {auto data alloc.allocate(e - b);return{ data, std::uninitialized_copy(b, e, data) }; }void StrVec::free() {if (elements){for_each(elements, first_free, this { alloc.destroy(rhs); });alloc.deallocate(elements, cap - elements);} }void StrVec::range_initialize(const std::string *first, const std::string *last) {auto newdata alloc_n_copy(first, last);elements newdata.first;first_free cap newdata.second; }StrVec::StrVec(const StrVec rhs) {range_initialize(rhs.begin(), rhs.end()); }StrVec::StrVec(std::initializer_liststd::string il) {range_initialize(il.begin(), il.end()); }StrVec::~StrVec() {free(); }StrVec StrVec::operator (const StrVec rhs) {auto data alloc_n_copy(rhs.begin(), rhs.end());free();elements data.first;first_free cap data.second;return *this; }void StrVec::alloc_n_move(size_t new_cap) {auto newdata alloc.allocate(new_cap);auto dest newdata;auto elem elements;for (size_t i 0; i ! size(); i)alloc.construct(dest, std::move(*elem));free();elements newdata;first_free dest;cap elements new_cap; }void StrVec::reallocate() {auto newcapacity size() ? 2 * size() : 1;alloc_n_move(newcapacity); }void StrVec::reserve(size_t new_cap) {if (new_cap capacity()) return;alloc_n_move(new_cap); }void StrVec::resize(size_t count) {resize(count, std::string()); }void StrVec::resize(size_t count, const std::string s) {if (count size()){if (count capacity()) reserve(count * 2);for (size_t i size(); i ! count; i)alloc.construct(first_free, s);}else if (count size()){while (first_free ! elements count)alloc.destroy(–first_free);} }StrVec::StrVec(StrVec s) NOEXCEPT : elements(s.elements), first_free(s.first_free), cap(s.cap) {// leave s in a state in which it is safe to run the destructor.s.elements s.first_free s.cap nullptr; }StrVec StrVec::operator (StrVec rhs) NOEXCEPT {if (this ! rhs){free();elements rhs.elements;first_free rhs.first_free;cap rhs.cap;rhs.elements rhs.first_free rhs.cap nullptr;}return *this; }bool operator(const StrVec lhs, const StrVec rhs) {return (lhs.size() rhs.size() std::equal(lhs.begin(), lhs.end(), rhs.begin())); }bool operator!(const StrVec lhs, const StrVec rhs) {return !(lhs rhs); }bool operator(const StrVec lhs, const StrVec rhs) {return std::lexicographical_compare(lhs.begin(), lhs.end(), rhs.begin(), rhs.end()); }bool operator(const StrVec lhs, const StrVec rhs) {return rhs lhs; }bool operator(const StrVec lhs, const StrVec rhs) {return !(rhs lhs); }bool operator(const StrVec lhs, const StrVec rhs) {return !(lhs rhs); }StrVec StrVec::operator(std::initializer_liststd::string il) {*this StrVec(il);return *this; }练习14.24 你在7.5.1节的练习7.40中曾经选择并编写了一个类你认为它应该含有拷贝赋值和移动赋值运算符吗如果是请实现它们。 头文件 #ifndef DATE_H #define DATE_H#ifndef _MSC_VER #define NOEXCEPT noexcept #else #define NOEXCEPT #endif#include iostream #include vectorclass Date {friend bool operator (const Date lhs, const Date rhs);friend bool operator (const Date lhs, const Date rhs);friend bool check(const Date d);friend std::ostream operator (std::ostream os, const Date d); public:typedef std::size_t Size;// default constructorDate() default;// constructor taking Size as daysexplicit Date(Size days);// constructor taking three SizeDate(Size d, Size m, Size y) : day(d), month(m), year(y) {}// constructor taking iostreamDate(std::istream is, std::ostream os);// copy constructorDate(const Date d);// move constructorDate(Date d) NOEXCEPT;// copy operatorDate operator (const Date d);// move operatorDate operator (Date rhs) NOEXCEPT;// destructor – in this case, user-defined destructor is not nessary.~Date() { std::cout destroying\n; }// membersSize toDays() const; //not implemented yet.Date operator (Size offset);Date operator -(Size offset);private:Size day 1;Size month 1;Size year 0; };static const Date::Size YtoD_400 146097; //365*400 ⁴⁰⁰⁄₄ -3 146097 static const Date::Size YtoD_100 36524; //365*100 ¹⁰⁰⁄₄ -1 36524 static const Date::Size YtoD_4 1461; //365*4 1 1461 static const Date::Size YtoD_1 365; //365// normal year static const std::vectorDate::Size monthsVec_n { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };// leap year static const std::vectorDate::Size monthsVec_l { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };// non-member operators: - !
// std::ostream operator (std::ostream os, const Date d); std::istream operator (std::istream is, Date d); int operator - (const Date lhs, const Date rhs); bool operator (const Date lhs, const Date rhs); bool operator !(const Date lhs, const Date rhs); bool operator (const Date lhs, const Date rhs); bool operator (const Date lhs, const Date rhs); bool operator (const Date lhs, const Date rhs); bool operator (const Date lhs, const Date rhs); Date operator - (const Date lhs, Date::Size rhs); Date operator (const Date lhs, Date::Size rhs);// utillities: bool check(const Date d); inline bool isLeapYear(Date::Size y);// check if the date object passed in is valid inline bool check(const Date d) {if (d.month 0 || d.month 12)return false;else{// month 1 3 5 7 8 10 12if (d.month 1 || d.month 3 || d.month 5 || d.month 7 ||d.month 8 || d.month 10 || d.month 12){if (d.day 0 || d.day 31) return false;elsereturn true;}else{// month 4 6 9 11if (d.month 4 || d.month 6 || d.month 9 || d.month 11){if (d.day 0 || d.day 30) return false;elsereturn true;}else{// month 2if (isLeapYear(d.year)){if (d.day 0 || d.day 29) return false;elsereturn true;}else{if (d.day 0 || d.day 28) return false;elsereturn true;}}}} }inline bool isLeapYear(Date::Size y) {if (!(y % 400)){return true;}else{if (!(y % 100)){return false;}elsereturn !(y % 4);} } #endif // DATE_HCPP文件 #include exercise14_24.h #include algorithm// constructor taking Size as days // the argument must be within (0, 2^32) Date::Date(Size days) {// calculate the yearSize y400 days / YtoD_400;Size y100 (days - y400*YtoD_400) / YtoD_100;Size y4 (days - y400*YtoD_400 - y100*YtoD_100) / YtoD_4;Size y (days - y400*YtoD_400 - y100*YtoD_100 - y4*YtoD_4) / 365;Size d days - y400*YtoD_400 - y100*YtoD_100 - y4*YtoD_4 - y * 365;this-year y400 * 400 y100 * 100 y4 * 4 y;// check if leap and choose the months vector accordinglystd::vectorSizecurrYear isLeapYear(this-year) ? monthsVec_l : monthsVec_n;// calculate day and month using find_if lambdaSize D_accumu 0, M_accumu 0;// bug fixed: the variabbles above hade been declared inside the find_if as static// which caused the bug. It works fine now after being move outside.std::find_if(currYear.cbegin(), currYear.cend(), {D_accumu m;M_accumu;if (d D_accumu){this-month M_accumu;this-day d m - D_accumu;return true;}elsereturn false;}); }// construcotr taking iostream Date::Date(std::istream is, std::ostream os) {is day month year;if (is){if (check(*this)) return;else{os Invalid input! Object is default initialized.;*this Date();}}else{os Invalid input! Object is default initialized.;*this Date();}}// copy constructor Date::Date(const Date d) : day(d.day), month(d.month), year(d.year) {}// move constructor Date::Date(Date d) NOEXCEPT : day(d.day), month(d.month), year(d.year) { std::cout copy moving; }// copy operator Date Date::operator (const Date d) {this-day d.day;this-month d.month;this-year d.year;return *this; }// move operator Date Date::operator (Date rhs) NOEXCEPT {if (this ! rhs){this-day rhs.day;this-month rhs.month;this-year rhs.year;}std::cout moving ;return *this; }// conver to days Date::Size Date::toDays() const {Size result this-day;// check if leap and choose the months vector accordinglystd::vectorSizecurrYear isLeapYear(this-year) ? monthsVec_l : monthsVec_n;// calculate result days by monthsfor (auto it currYear.cbegin(); it ! currYear.cbegin() this-month - 1; it)result *it;// calculate result days by yearsresult (this-year / 400) * YtoD_400;result (this-year % 400 / 100) * YtoD_100;result (this-year % 100 / 4) * YtoD_4;result (this-year % 4) * YtoD_1;return result; }// member operators: -Date Date::operator (Date::Size offset) {*this Date(this-toDays() offset);return *this; }Date Date::operator -(Date::Size offset) {if (this-toDays() offset)*this Date(this-toDays() - offset);else*this Date();return *this; }// non-member operators: - ! std::ostream operator (std::ostream os, const Date d) {os d.day d.month d.year;return os; }std::istream operator (std::istream is, Date d) {if (is){Date input Date(is, std::cout);if (check(input)) d input;}return is; }int operator -(const Date lhs, const Date rhs) {return lhs.toDays() - rhs.toDays(); }bool operator (const Date lhs, const Date rhs) {return (lhs.day rhs.day) (lhs.month rhs.month) (lhs.year rhs.year); }bool operator !(const Date lhs, const Date rhs) {return !(lhs rhs); }bool operator (const Date lhs, const Date rhs) {return lhs.toDays() rhs.toDays(); }bool operator (const Date lhs, const Date rhs) {return (lhs rhs) || (lhs rhs); }bool operator (const Date lhs, const Date rhs) {return !(lhs rhs); }bool operator (const Date lhs, const Date rhs) {return !(lhs rhs); }Date operator - (const Date lhs, Date::Size rhs) { // ^^^ rhs must not be larger than 2^32-1// copy lhsDate result(lhs);result - rhs;return result; }Date operator (const Date lhs, Date::Size rhs) { // ^^^ rhs must not be larger than 2^32-1// copy lhsDate result(lhs);result rhs;return result; }练习14.25 上题的这个类还需要定义其他赋值运算符吗如果是请实现它们同时说明运算对象应该是什么类型并解释原因。 是。如上题。 练习14.26 为你的 StrBlob 类、StrBlobPtr 类、StrVec 类和 String 类定义下标运算符。 练习14.27 为你的 StrBlobPtr 类添加递增和递减运算符。 练习14.28 为你的 StrBlobPtr 类添加加法和减法运算符使其可以实现指针的算术运算。 练习14.29 为什么不定义const 版本的递增和递减运算符 因为递增和递减会改变对象本身所以定义 const 版本的毫无意义。 练习14.30 为你的 StrBlobPtr 类和在12.1.6节练习12.22中定义的 ConstStrBlobPtr 的类分别添加解引用运算符和箭头运算符。注意因为 ConstStrBlobPtr 的数据成员指向const vector所以ConstStrBlobPtr 中的运算符必须返回常量引用。