读书笔记之：C++程序设计语言——题解

练习5.9 自引用

、

程序代码如下：

#include <iostream>
using namespace std;
enum Context{
    c_comment,cpp_comment,string_literal,char_literal,file_end
};
void handle_c_comment(){
    char ch;
    while(cin.get(ch)){
        if(ch=='*'){
            while(cin.get(ch)&&ch=='*')
                ;
            if(ch=='/')
                break;
        }
    }
}
void handle_cpp_comment(){
    char ch;
    while(cin.get(ch)&&ch!='\n')
        ;
}
void handle_literal(char delimiter){
    cout<<delimiter;
    char ch;
    while(cin.get(ch)){
        cout<<ch;
        if(ch==delimiter)
            break;
        else if (ch=='\\')
            cin.get(ch)&&cout<<ch;
    }
}
Context handle_code(){
    char ch;
    while(cin.get(ch)){
        switch(ch){
            case '/':
                if(!cin.get(ch)){
                    cout<<'/';
                    return file_end;
                }
                else {
                    if(ch=='*')
                        return c_comment;
                    else if(ch=='/')
                        return cpp_comment;
                    else{
                        cout<<'/';
                        cin.putback(ch);
                        break;
                    }
                }
            case '\"':
                return string_literal;
            case '\'':
                return char_literal;
            default:
                cout<<ch;
        }
    }
    return file_end;    
}
int main(int argc,char**argv){
    if(argc!=1){
        cerr<<"This program takes no arguments.\n";
        return -1;
    }
    else{
        Context contxt;
        while((contxt=handle_code())!=file_end)
            switch(contxt){
                case c_comment:
                    handle_c_comment();
                    break;
                case cpp_comment:
                    handle_cpp_comment();
                    break;
                case string_literal:
                    handle_literal('\"');
                    break;
                case char_literal:
                    handle_literal('\'');
                    break;
            }
    }
    return 0;
}

 

代码如下：

#include <iostream>
#include <typeinfo>
using namespace std;
#define CTOR(CC){                 \
    cout<<#CC" Constructor:"      \
        <<typeid(*this).name()<<'\n';\
    from_outside(this);\
    cout<<'\n';\
}
#define DTOR(CC){ \
    cout<<#CC " destructor: "\
        <<typeid(*this).name()<<'\n';\
    from_outside(this);\
    cout<<'\n';\
}
struct A;
void from_outside(A *object);
struct A{
    A() CTOR(A)
    ~A() DTOR(A)
};
void from_outside(A *object){
    cout<<" Located at address: "<<(void*)object
        <<"\nFrom outside: "<<typeid(*object).name()
        <<endl;
}

struct B;
void from_outside(B *object);
struct B: A{
    B() CTOR(B)
    virtual ~B() DTOR(B)
};
void from_outside(B *object){
    cout<<" Located at address: "<<(void*)object
        <<"\nFrom outside: "<<typeid(*object).name()
        <<endl;
}

struct C: B{
    C() CTOR(C)
    virtual ~C() DTOR(C)
};
struct D: B{
    D() CTOR(D)
    virtual ~D() DTOR(D)
};

struct E;
void from_outside(E* object);
struct E: C,D{
    E() CTOR(E)
    virtual ~E() DTOR(E)
};
void from_outside(E* object){
    from_outside((C*)object);
    from_outside((D*)object);
}
struct F: virtual B{
    F() CTOR(F)
    virtual ~F() DTOR(F)
};
struct G:virtual B{
    G() CTOR(G)
    virtual ~G() DTOR(G)
};
struct H:F,G{
    H() CTOR(H)
    virtual ~H() DTOR(H)
};
struct I;
void from_outside(I* object);
struct I:E,H{
    I() CTOR(I)
        virtual ~I() DTOR(I)
};
void from_outside(I* object){
    from_outside((C*)object);
    from_outside((D*)object);
    from_outside((H*)object);
}
int main(){
    I complex_obect;
    cout <<"Total size of I-object :"<<sizeof (I)<<endl;
}

程序输出如下：

 

 

代码如下：

#include <iostream>
#include <string>
#include <cctype>
#include <ctime>
#include <cstdio>
using namespace std;

bool read_string(string &s){
    int const buffer_size=100;
    char buffer[buffer_size+1];
    int i=0,c;
    while((c=cin.get())&&cin&&isspace(c))
        ;
    while((c=cin.get())&&cin&&!isspace(c)
            &&i!=buffer_size){
        buffer[i++]=char(c);
    }
    buffer[i]='\0';
    s.assign(buffer,i);
    if(cin){
        cin.putback(c);
        if(!isspace(c)){
            string remainder;
            read_string(remainder);
            s.append(remainder);
        }
        return true;
    }
    else
        return false;
}
bool read_string2(string& s){
    int const buffer_size=100;
    char buffer[buffer_size+1];
    int i=0,c;
    while((c=getc(stdin))!=EOF&&isspace(c))
        ;
    while((c=getc(stdin))!=EOF&&!isspace(c)
            &&i!=buffer_size){
        buffer[i++]=char(c);
    }
    buffer[i]='\0';
    s.assign(buffer,i);
    if(c!=EOF){
        ungetc(c,stdin);
        if(!isspace(c)){
            string remainder;
            read_string(remainder);
            s.append(remainder);
        }
        return true;
    }
    else
        return false;

}
int main(){
    string word;
    int n=0;
    bool not_eof;
    clock_t start=clock();
#if defined(SIMPLE)
    while(cin)
    {
        cin>>word;
        n++;
    }
#elif defined(SIMPLE2)
    do{
        not_eof=read_string(word);
        ++n;
    }while(not_eof);
#else
    do{
        not_eof=read_string2(word);
        ++n;
    }while(not_eof);

#endif
    printf("Read %d words in %f seconds.\n",n,(clock()-start)*1.0/CLOCKS_PER_SEC);
    return 0;
}