ch10

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1. size_t、ptrdiff_t

#include "stdafx.h"
#include 
#include
#include
#include   //for rand()
using namespace std;



class Histogram{
public:
    Histogram(ptrdiff_t minval, size_t gap, size_t n_bins);
    ~Histogram(){ delete[] bin_; }
    void record(ptrdiff_t);
    void output_to(ostream&);
private:
    ptrdiff_t const minval_, maxval_;  //最小，最大边界
    size_t const gap_;  //区间数
    size_t * const bin_;  //存储区
    size_t n_samll_, n_large_;
};

Histogram::Histogram(ptrdiff_t minval, size_t gap, size_t n_bins):minval_(minval),
        maxval_(minval+n_bins*gap-1),gap_(gap),bin_(new size_t[n_bins]),n_samll_(0),n_large_(0){
    assert(gap!=0&&n_bins!=0);
    for (int k = 0; k != n_bins; ++k){
        bin_[k] = 0;
    }
}

void Histogram::record(ptrdiff_t datapoint){
    if (datapoint < minval_){
        ++n_samll_;
    }
    else if (datapoint>maxval_){
        ++n_large_;
    }
    else
        ++bin_[(datapoint - minval_) / gap_];

}

void Histogram::output_to(ostream& o){
    o << "< " << minval_ << ": "<< n_samll_ << endl;
    for (ptrdiff_t left = minval_; left < maxval_; left += gap_){
        o << left << "..." << left + gap_ - 1 << " : " << bin_[(left - minval_) / gap_] << endl;
    }
    o << " > " << maxval_ << " : " << n_large_ << endl;
}

int main(){
    Histogram h (0,10,10);      // 间隔为10的10个区间
    for (int k = 0; k != 10000; ++k){
        h.record((int)(10.0*rand() / rand()));
    }
    h.output_to(cout);
    return 0;
}

#include "stdafx.h"
#include 
#include
#include
#include
using namespace std;

//向量方式
class Vec_queue{
    // unsigned == unsigned int。两者一样
public:
    inline Vec_queue(unsigned capacity = default_capacity);
    ~Vec_queue(){ delete[] queue_; }
    bool empty(){ return head_ == tail_; }
    inline char dequeue();
    inline void enqueue(char);
    bool full() const{ return head_ == (tail_ + 1) %capacity_; }
    static bool const fixed_capacity = true;
private:
    static unsigned const default_capacity = 32;  //默认大小
    char * queue_;  //数组指针
    unsigned head_, tail_;  //头尾
    unsigned const capacity_; //空间大小

};

inline Vec_queue::Vec_queue(unsigned c)
            :queue_(new char[c+1]),head_(0),tail_(0),capacity_(c+1){
}

inline char Vec_queue::dequeue(){
    if (!empty()){
        char c = queue_[head_];
        head_ = (head_ + 1) % capacity_;
        return c;
    }
    else
    {
        throw underflow_error(string("queue empty!"));
    }
}

inline void Vec_queue::enqueue(char c){
    if (!full()){
        queue_[tail_] = c;
        tail_ = (tail_ + 1) % capacity_;
    }
    else
    {
        throw overflow_error(string("queue overflow!"));
    }
}

//链表方式
class Char_queue{
public:
    Char_queue(unsigned capacity = 0) :in_(&out_cell_){
        out_cell_.next_ = 0; 
    }
    ~Char_queue();
    bool empty() const{ return in_==&out_cell_; }  //尾指针等于第一个节点
    char dequeue();
    void enqueue(char);
    bool full() const{ return false; }  //链表设置为永远不满
    static bool const fixed_capacity = false;
private:
    struct Cell    //一个单元包括值和指向下一个节点的指针
    {
        Cell * next_;
        char c_;
    };
    Cell out_cell_;//头节点
    Cell * in_; //尾指针
};

Char_queue::~Char_queue(){//只保留头结点
    for (Cell *p = out_cell_.next_; p;){
        Cell * victim = p;
        p = p->next_;
        delete victim;
    }
}

char Char_queue::dequeue(){
    if (!empty()){
        Cell * victim = out_cell_.next_;
        if (victim == in_){//头节点下一个节点是尾节点
            in_ = &out_cell_;//尾指针指向头结点
        }
        char c = victim->c_;
        out_cell_.next_ = victim->next_;
        delete victim;
        return c;
    }
else
    throw underflow_error(string("queue empty!!!"));

}


void Char_queue::enqueue(char c){
    in_->next_ = new(nothrow)Cell;
    if (!in_->next_)
        throw overflow_error(string("queue  分配空间失败! "));
    in_ = in_->next_;
    in_->next_ = 0;
    in_->c_ = c;
}

int main(){
    Char_queue q(4);
    while (1){
        if (q.empty()){
            cout << "queue is empty!" << endl;
        }
        else if (q.full()){
            cout << "queue is full !!" << endl;
        }
        char cmd, ch;
        cout << "请输入命令： e(E):入列；d(D):出列；q(Q):退出;" << endl;
        cin >> cmd;
        try{
            switch (cmd)
            {
            case 'e':case 'E':cout << "输入入列的值："; cin >> ch; q.enqueue(ch); break;
            case 'd': case 'D': cout << "Dequeued " << q.dequeue() << endl; break;
            case 'q': case 'Q': cout << "Quiting !" << endl; return 0 ;
            default:
                cerr << "Invalid command!" << endl;
                break;
            }
        }
        catch(exception &e){
            cerr << " Caught exception: " << typeid(e).name() << "  ( " << e.what() << " )" << endl;
        }

    }
}

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1.c++中的#include

1. C++中nothrow的介绍及使用

#include 

int main() {
   std::cout << "Hello, world!\n";
}

struct GlobalBracket {
   GlobalBracket() { std::cout << "Initialize\n"; }
   ~GlobalBracket() { std::cout << "Clean up\n"; }
} global_bracket_variable;

#include "stdafx.h"
#include 
#include
#include
#include

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