1.5节中有对vector的简单介绍，所以就写了一个程序，用于表达书上运用vector的思想：
#include在第二章中讲述如何编写函数，举了Fibonacci函数的例子:#include #include #include using namespace std;//备注：这里用到rand当然不好，因为rand并不是一个真正的随机数。void getNum(vector< vector > &ivvec, int &firstNum, int &secondNum, int &thirdNum){ int randomSeq = 0; //随机的序列 int randomBegin = 0; //随机序列中随机的第一个元素的索引 randomSeq = rand() % 6; randomBegin = rand() % 6; firstNum = ivvec[randomSeq][randomBegin]; secondNum = ivvec[randomSeq][randomBegin + 1]; thirdNum = ivvec[randomSeq][randomBegin + 2];}int main(void){ int arrFib[8] = {1, 1, 2, 3, 5, 8, 13, 21}; vector iFibVec(arrFib, arrFib + 8); int arrLuc[8] = {1, 3, 4, 7, 11, 18, 29, 47}; vector iLucVec(arrLuc, arrLuc + 8); int arrPel[8] = {1, 2, 5, 12, 29, 70, 169, 408}; vector iPelVec(arrPel, arrPel + 8); int arrTri[8] = {1, 3, 6, 10, 15, 21, 28, 36}; vector iTriVec(arrTri, arrTri + 8); int arrSqu[8] = {1, 4, 9, 16, 25, 36, 49, 64}; vector iSquVec(arrSqu, arrSqu + 8); int arrPen[8] = {1, 5, 12, 22, 35, 51, 70, 92}; vector iPenVec(arrPen, arrPen + 8); vector< vector > ivvec; ivvec.push_back(iFibVec); ivvec.push_back(iLucVec); ivvec.push_back(iPelVec); ivvec.push_back(iTriVec); ivvec.push_back(iSquVec); ivvec.push_back(iPenVec); //从ivvec中提取三个随机的数 bool bTry = true; //用户想再次尝试 const int maxTries = 5; //最多尝试次数 int numTries = 0; //用户尝试的次数 int numRight = 0; //用户正确的次数 while (bTry) { int firstNum = 0; int secondNum = 0; int thirdNum = 0; getNum(ivvec, firstNum, secondNum, thirdNum); cout << "the first number is: " << firstNum << "\nand the second number is: " << secondNum << endl; cout << "please enter the third number: "; int userNum = 0; cin >> userNum; string userSelect; if (userNum == thirdNum) { numRight++; numTries++; cout << "you are right.do you want to try another numbers?(N/n to break, another continue)" << endl; cin >> userSelect; } else { if (numTries > maxTries) { cout << "sorry, you have tried max times." << endl; break; } numTries++; cout <<"you are wrong. do you wang to try another numbers?(N/n to break, another continue)" << endl; cin >> userSelect; } if ((userSelect == "n") || (userSelect == "N")) { break; } } cout << "the rate success is: " << (numRight * 1.0 / numTries) * 100 << "%" << endl; return 0;}
#include调用一个函数：using namespace std;bool fibon_elem(int, int &);int main(void){ int pos; cout << "please enter a position:"; cin >> pos; int elem; if (fibon_elem(pos, elem)) { cout << "element #" << pos<< " is " << elem << endl; } else { cout << "sorry. could not calculate element#" << pos << endl; } return 0;}bool fibon_elem(int pos, int &elem){ if ((pos <= 0) || (pos > 1024)) { elem = 0; return false; } elem = 1; int n_2 = 1; int n_1 = 1; for (int ix = 3; ix <= pos; ix++) { elem = n_1 + n_2; n_2 = n_1; n_1 = elem; } return true;}
#include关于如何提供默认参数值：#include using namespace std;void display(vector ivec);void swap(int &val1, int &val2);void bubble_sort(vector &ivec);int main(void){ int ia[8] = {8, 34, 3, 13, 1, 21, 5, 2}; vector ivec(ia, ia + 8); cout << "vector before sort" << endl; display(ivec); bubble_sort(ivec); cout << "vector after sort:" << endl; display(ivec); return 0;}void display(vector ivec){ for (int ix = 0; ix < ivec.size(); ix++) { cout << ivec[ix] << " "; } cout << endl;}void swap(int &val1, int &val2){ int temp; temp = val1; val1 = val2; val2 = temp;}void bubble_sort(vector &ivec){ for (int ix = 0; ix < ivec.size(); ix++) { for (int jx = ix + 1; jx < ivec.size(); jx++) { if (ivec[ix] > ivec[jx]) { swap(ivec[ix], ivec[jx]); } } }}
#include使用局部静态对象：#include #include using namespace std;void swap(int &val1, int &val2, ofstream *ofil = 0);template void bubble_sort(vector &ivec, T *ofil = 0);void display(vector &ivec, ostream &os = cout);int main(void){ int ia[8] = {8, 7, 6, 5, 4, 3, 2, 1}; vector ivec(ia, ia + 8); cout << "before sort:" << endl; display(ivec); bubble_sort (ivec, &cout); cout << "after sort:" << endl; display(ivec, cout); return 0;}void display(vector &ivec, ostream &os){ for (int ix = 0; ix < ivec.size(); ix++) { os << ivec[ix] << " "; } os << endl;}void swap(int &val1, int &val2, ofstream *ofil){ int temp; temp = val1; val1 = val2; val2 = temp; if (ofil != 0) { (*ofil) << "swap " << val1 << " and " << val2 << endl; }}template void bubble_sort(vector &ivec, T *ofil /* = 0 */){ for (int ix = 0; ix < ivec.size(); ix++) { for (int jx = ix + 1; jx < ivec.size(); jx++) { if (ivec[ix] > ivec[jx]) { if (ofil != 0) { (*ofil) << "about to call swap! ix: " << ix << " jx: " << jx << "\tswapping :" << ivec[ix] << " with " << ivec[jx] << endl; } swap(ivec[ix], ivec[jx]); } } }}
#include函数指针的作用，增加灵活性：#include using namespace std;vector< int > fibon_seq(int size);int main(void){ vector< int > ivec; ivec = fibon_seq(10); ivec = fibon_seq(5); for (int ix = 0; ix < ivec.size(); ix++) { cout << ivec[ix] << " "; } cout << endl; return 0;}vector< int > fibon_seq(int size){ static vector< int > elems; for (int ix = elems.size(); ix < size; ix++) { if ((ix == 0) || (ix == 1)) { elems.push_back(1); } else { elems.push_back(elems[ix - 1] + elems[ix - 2]); } } return elems;}
#include#include #include using namespace std;void fun1(int iValue){ cout << iValue << endl;}void fun2(float fValue){ cout << fValue << endl;}void fun3(string sValue){ cout << sValue << endl;}template void fun(void (*subfun)(funType), funType val){ (*subfun)(val);}int main(void){ fun (fun1, 12); fun (fun2, 12.3); fun (fun3, "hello world"); return 0;}
第三章介绍设计泛型算法的时候，自己就先设计了一下，运行了还可以，当然，用到了函数指针的思想：
#include然而，书本上提供了一种仿函数和配接器的能力，来完成这个泛型的算法：#include using namespace std;template bool lessThan(T val, T maxValue){ return (val < maxValue);}template vector< T > less_than_10(IteratorType first, IteratorType last, bool (*fun)(T,T ), T maxValue){ vector< T > ivec; for ( ; first != last; first++ ) { if (fun(*first, maxValue)) { ivec.push_back(*first); } } return ivec;}int main(void){ vector< int > ivec; vector< int > ivecres; for ( int i = 0; i < 20; i++) { ivec.push_back(i); } ivecres = less_than_10 ::iterator, int>(ivec.begin(), ivec.end(), lessThan, 10); for (int i = 0; i < ivecres.size(); i++) { cout << ivecres[i] << " "; } return 0;}
当然，书上的方法更好：
#include书上讲到输入输出流的时候，我就写了一个例子：#include #include #include using namespace std;template OutputIteratorfilter(InputIterator first, InputIterator last, OutputIterator at, const ElemType val, Comp pred){ while ((first = find_if(first, last, bind2nd(pred, val))) != last) { cout << "found value: " << *first << endl; *at++ = *first++; } return at;}int main(void){ vector ivec; for (int i = 0; i < 20; i++) { ivec.push_back(i); } vector ivec2; filter(ivec.begin(), ivec.end(), back_inserter(ivec2), 10, less ()); for (int i = 0; i < ivec2.size(); i++) { cout << ivec2[i] << " "; } cout << endl; return 0;}
#include我只能说，这个例子太美了。#include #include using namespace std;int main(void){ copy(istream_iterator (cin), istream_iterator (), ostream_iterator (cout, " ")); return 0;}
第四章中如何实现一个class，第一个例子就是stack，编写如下：
stack.h
#includestack.cpp#include #include #include using namespace std;class Stack{public: bool push(const string); bool pop(string &elem); bool peek(string &elem); bool empty(); bool full(); bool find(string elem); int count(string elem); int size(){ return _stack.size(); }private: vector _stack;};
#include "Stack.h"inline bool Stack::empty(){ return _stack.empty();}inline bool Stack::full(){ return _stack.size() == _stack.max_size();}bool Stack::push(const string elem){ if (full()) { return false; } _stack.push_back(elem); return true;}bool Stack::pop(string &elem){ if (empty()) { return false; } elem = _stack.back(); _stack.pop_back(); return true;}bool Stack::peek(string &elem){ if (empty()) { return false; } elem = _stack.back(); return true;}bool Stack::find(string elem){ return ::find(_stack.begin(), _stack.end(), elem) != _stack.end();}int Stack::count(string elem){ return ::count(_stack.begin(), _stack.end(), elem);} 在进行类的设计的时候，有一点要注意就是：析构函数，赋值操作符重载，复制构造函数三者同存同亡，是个好的设计理念。 第四章里面设计了一个类，但是我怎么都是弄混了，于是自己写了这个类，当然和书上的不同，但是运行的结果是一样的：
#include#include #include using namespace std;class Triangular{public: Triangular( int length = 1, int beg_pos = 1) { _length = length; _beg_pos = beg_pos; for (int i = beg_pos; i < beg_pos + length; i++) { sivec.push_back(i * (i + 1) / 2); } } int beg_pos() const { return _beg_pos; } int length() const { return _length; } void show() const { for (int i = 0; i < sivec.size(); i++) { cout << sivec[i] << " "; } } int sum() const { int sum = 0; for (int i = 0; i < sivec.size(); i++) { sum += sivec[i]; } return sum; }private: int _length; int _beg_pos; vector sivec;};ostream& operator<<(ostream &os, Triangular &rhs){ os << "( " << rhs.beg_pos() << " , " << rhs.length() << " ) "; rhs.show(); return os;}int main(void){ Triangular tr(4); cout << tr << "--sum of elements:" << tr.sum() << endl; Triangular tr2(4, 3); cout << tr2 << "--sum of elements:" << tr2.sum() << endl; Triangular tr3(4, 8); cout << tr3 << "--sum of elements:" << tr3.sum() << endl; return 0;}
在第四章的中间部分，有一个问题提出是如何设计iterator class，于是自己照着书上的方法写了一下，发现可以运行，就粘贴上来了。当然，代码的构架方面和书上的意义，只是编写方式不同而已：
triangular_iterator.h：
#includemain.cpp:#include #include using namespace std;class Triangular_iterator{public: Triangular_iterator(int index) : _index(index - 1){} bool operator==(const Triangular_iterator&) const; bool operator!=(const Triangular_iterator&) const; int operator*() const; Triangular_iterator& operator++(); Triangular_iterator operator++(int);private: void check_integrity() const; int _index;};class Triangular{ friend Triangular_iterator;public: Triangular( int length = 1, int beg_pos = 1) { _length = length; _beg_pos = beg_pos; _elems.clear(); //这里进行了一次折中的运算。因为iterator要求_elems必须为static， //但是static的性质导致_elems的值每次都在原基础上增加，所以进行clear操作 for (int i = beg_pos; i < beg_pos + length; i++) { _elems.push_back(i * (i + 1) / 2); } } typedef Triangular_iterator iterator; Triangular_iterator begin() { return Triangular_iterator(1); //这里进行了特殊的修改，为了符合我自己编写代码的习惯，符合_elems为static并且每次都变的情况。 } Triangular_iterator end() { return Triangular_iterator(1 + _length); } int beg_pos() const { return _beg_pos; } int length() const { return _length; } static void show() { for (int i = 0; i < _elems.size(); i++) { cout << _elems[i] << " "; } } static int sum() { int sum = 0; for (int i = 0; i < _elems.size(); i++) { sum += _elems[i]; } return sum; } static void gen_elements(int index) { for (int i = _elems.size(); i < index; i++) { _elems.push_back(i * (i + 1) / 2); } }private: int _length; int _beg_pos; static vector _elems;};vector Triangular::_elems;ostream& operator<<(ostream &os, Triangular &rhs){ os << "( " << rhs.beg_pos() << " , " << rhs.length() << " ) "; rhs.show(); return os;}inline bool Triangular_iterator::operator==(const Triangular_iterator &rhs) const{ return _index == rhs._index;}inline bool Triangular_iterator::operator!=(const Triangular_iterator &rhs) const{ return !(*this == rhs);}inline int Triangular_iterator::operator*() const{ check_integrity(); return Triangular::_elems[_index];}inline void Triangular_iterator::check_integrity() const{ if (_index >= Triangular::_elems.size()) { Triangular::gen_elements(_index + 1); }}inline Triangular_iterator& Triangular_iterator::operator++(){ ++_index; check_integrity(); return *this;}inline Triangular_iterator Triangular_iterator::operator++(int){ Triangular_iterator tmp = *this; ++_index; check_integrity(); return tmp;}
#include "Triangular_iterator.h"int main(void){ Triangular tr(32); cout << tr << "--sum of elements:" << tr.sum() << endl; Triangular tr2(4, 3); cout << tr2 << "--sum of elements:" << tr2.sum() << endl; Triangular tr3(4, 8); cout << tr3 << "--sum of elements:" << tr3.sum() << endl; Triangular tr4(20, 12); Triangular::iterator it = tr4.begin(); Triangular::iterator end_it = tr4.end(); cout << "triangular series of " << tr4.length() << " elements\n"; cout << tr4 << endl; while (it != end_it) { cout << *it << " "; ++it; } cout << endl; return 0;} 关于仿函数： #include#include using namespace std;class LessThan{public: LessThan( int val ) : _val(val){} int comp_val() const {return _val;} void comp_val( int nval ){ _val = nval;} bool operator()( int value ) const { return value < _val; }private: int _val;};int count_less_than( const vector &vec, int comp ){ LessThan lt(comp); int count = 0; for ( int ix = 0; ix < vec.size(); ix++ ) { if ( lt( vec[ix] ) ) { ++count; } } return count;}int main(void){ vector< int > ivec; for ( int i = 0; i < 20; i++ ) { ivec.push_back(i); } cout << count_less_than( ivec, 10 ) << endl; return 0;}
第五章面向对象编程风格中，刚开头举了一个图书馆的例子，代码如下：
#include#include using namespace std;class LibMat{public: LibMat() { cout << "LibMat::Libmat() default constructor!\n"; } virtual ~LibMat() { cout << "LibMat::~LibMat() default destructor!\n"; } virtual void print() const { cout << "LibMat::print() -- I am a LibMat object!\n"; }};class Book : public LibMat{public: Book(const string &title, const string &author) :_title(title), _author(author) { cout << "Book::Book( " << _title << " , " << _author << " ) constructor\n"; } virtual ~Book() { cout << "Book::~Book() destructor!\n"; } virtual void print() const { cout << "Book::print() -- I am a Book object!\n" << "My title is: " << _title << "\n" << "My author is: " << _author << endl; } const string &title() const { return _title; } const string &author() const { return _author; }protected: string _title; string _author;};class AudioBook : public Book{public: AudioBook( const string &title, const string &author, const string &narrator) :Book(title, author), _narrator(narrator) { cout << "audiobook:audiobook( " << _title << " , " << _author << " ," << _narrator << " ) constructor\n"; } ~AudioBook() { cout << "audiobook::~audiobook() destructor!\n"; } virtual void print() const { cout << "AudioBook::print() -- I am an AudioBook object!\n" << "My title is: " << _title << "\n" << "My author is: " << _author << "\n" << "My narrator is: " << _narrator << endl; } const string &narrator() const { return _narrator; }protected: string _narrator;};void print(const LibMat &mat){ cout << "in global print(): about to print mat.print()\n"; mat.print();}int main(void){ AudioBook ab("随遇而安","孟非", "good"); print(ab); return 0;}
在进行类的继承和多态的问题上，书上讲了一个非常好的例子：
num_sequence.h：
#includeFibonacci.h：using namespace std;class num_sequence{public: virtual ~num_sequence(){} virtual int elem(int pos) const = 0; virtual const char* what_am_i() const = 0; static int max_elems() { return _max_elems; } virtual ostream& print(ostream &os = cout) const = 0;protected: virtual void gen_elems(int pos) const = 0; bool check_integrity(int pos, int size) const; const static int _max_elems = 1024;};bool num_sequence::check_integrity(int pos, int size) const{ if (pos <= 0 || pos > _max_elems) { cerr << "!! invalid position: " << pos << " cannot honor request\n"; return false; } if (pos > size) gen_elems(pos); return true;}ostream& operator<<(ostream &os, const num_sequence &ns){ return ns.print(os);}
#include "num_sequence.h"#includemain.cpp：#include using namespace std;class Fibonacci : public num_sequence{public: Fibonacci(int len = 1, int beg_pos = 1) :_length(len), _beg_pos(beg_pos){} virtual int elem(int pos) const; virtual const char* what_am_i() const { return "Fibonacci";} virtual ostream& print(ostream &os = cout) const; int length() const{return _length;} int beg_pos() const {return _beg_pos;}protected: virtual void gen_elems(int pos) const; int _length; int _beg_pos; static vector _elems;};vector Fibonacci::_elems;int Fibonacci::elem(int pos) const{ if (!check_integrity(pos, _elems.size())) { return 0; } if (pos > _elems.size()) Fibonacci::gen_elems(pos); return _elems[pos - 1];}void Fibonacci::gen_elems(int pos) const{ if (_elems.empty()) { _elems.push_back(1); _elems.push_back(1); } if (_elems.size() <= pos) { int ix = _elems.size(); int n_2 = _elems[ix - 2]; int n_1 = _elems[ix - 1]; for (; ix <= pos; ++ix) { int elem = n_2 + n_1; _elems.push_back(elem); n_2 = n_1; n_1 = elem; } }}ostream& Fibonacci::print(ostream &os) const{ int elem_pos = _beg_pos - 1; //之所以要减1，是因为索引是从0开始的 int end_pos = elem_pos + _length; if (end_pos > _elems.size()) Fibonacci::gen_elems(end_pos); while (elem_pos < end_pos) { os << _elems[elem_pos++] << " "; } return os;}
#include#include "Fibonacci.h"using namespace std;int main(void){ Fibonacci fib; cout << fib << endl; Fibonacci fib2(4); cout << fib2 << endl; Fibonacci fib3(8, 12); cout << fib3 << endl; return 0;}
第六章的模板和第七章的异常不看了。还好吧，一步步来，不急。
接下去就慢慢的工作，然后看完《C++ Primer》，《the C++ programming language》和《C和指针》。
今年下半年不求什么，只要把这四本书看完就可以了。
顺便看50本的额外小说，加油。
工作就好好工作。