CPP_Basic_Code_P7.1-PP7.13.10

CPP_Basic_Code_P7.1-PP7.13.10

//  The Notes Created by Z-Tech on 2017/2/17.//  All Codes Boot on 《C++ Primer Plus》V6.0//  OS：MacOS 10.12.4//  Translater：clang/llvm8.0.0 &g++4.2.1//  Editer：iTerm 2&Sublime text 3//  IDE: Xcode8.2.1&Clion2017.1//P7.1#include <iostream>void simple();//声明没有返回值的函数int main(){    using namespace std;    cout<<"main() will call the function simple(): \n";    simple();    cout<<"main() is finisied with the simple() function.\n";    //cin.get();    return 0;}void simple()//具体的函数编写{    using namespace std;    cout<<"I'm but s simple function.\n";}//P7.2#include <iostream>void cheers(int);double cube(double x);//有返回值的函数int main(){    using namespace std;    cheers(5);    cout<<"Give me a number:\n";    double side;    cin>>side;    double volume=cube(side);    cout<<"A "<<side<<"-foot cube has a volume of ";    cout<<volume<<" cubic feet.\n";    cheers(cube(2));//2的立方为8    return 0;}void cheers(int n){    using namespace std;    for (int i=0;i<n;i++)        cout<<"cheers! ";    cout<<endl;}double cube(double x){    return x*x*x;}                                                                                                  //P7.3#include <iostream>using namespace std;void n_chars(char,int);int main(){    int times;    char ch;    cout<<"Enter a character: ";    cin>>ch;    while (ch!='q')//输入'q'则退出程序    {        cout<<"Enter an integer: ";        cin>>times;        n_chars(ch,times);//注意调用方式        cout<<"\nEnter another character or press the q-Key to quit: ";        cin>>ch;    }    cout<<"The value of times is "<<times<<".\n";    cout<<"Bye\n";    return 0;}void n_chars(char c,int n)//子函数全部使用内部的局部变量{    while (n-- >0)        cout<<c;}//P7.4#include <iostream>long double probability(unsigned numbers,unsigned picks);int main(){    using namespace std;    double total,choices;    cout<<"Enter the number of choices on the game card and\n"        "the number of picks allowed:\n";    while ((cin>>total>>choices)&&choices<=total)    {        cout<<"You have one chance in ";        cout<<probability(total,choices);        cout<<" of winning.\n";        cout<<"Next two numbers (q to quit): ";    }    cout<<"Bye\n";    return 0;}long double probability(unsigned numbers,unsigned picks)//形参{    long double result=1.0;    long double n;//提前定义局部变量    unsigned p;    for (n=numbers,p=picks;p>0;n--,p--)        result=result*n/p;//利用连乘实现计算且避免中间数过大    return result;//返回结果}//P7.5#include <iostream>const int ArSize=8;int sum_arr(int arr[],int n);//声明传递数组的函数，指针和整数//此处也可使用int* arr来实现数组的声明int main(){    using namespace std;    int cookies[ArSize] {1,2,4,8,16,32,64,128};    int sum=sum_arr(cookies,ArSize);//函数调用后赋值    cout<<"Total cookies eaten: "<<sum<<"\n";    return 0;}int sum_arr(int arr[],int n){    int total=0;    for (int i=0;i<n;i++)        total=total+arr[i];//传递的指针可当做数组名使用    return total;}//P7.6#include <iostream>const int ArSize=8;int sum_arr(int arr[],int n);int main(){    int cookies[ArSize] {1,2,4,8,16,32,64,128};    std::cout<<cookies<<" = array address, ";//数组名输出将输出数组地址    std::cout<<sizeof cookies<<" = sizeof cookies\n";//输出数组名大小将输出整个数组大小    int sum=sum_arr(cookies,ArSize);//函数调用后赋值    std::cout<<"Total cookies eaten: "<<sum<<std::endl;    sum=sum_arr(cookies,3);//传递参数指出数组只有三个元素从而计算前三者总和    std::cout<<"First three eaters ate "<<sum<<" cookies.\n";    sum=sum_arr(cookies+4,4);//使用指针加减来移动指针位置到第五个元素，往后四个    //此处也可以使用&cookies[4]来取代cookies+4，效果一样    std::cout<<"Last four eaters ate "<<sum<<" cookies.\n";    return 0;}int sum_arr(int arr[],int n){    int total=0;    std::cout<<arr<<" = arr, ";//输出指针（数组名）地址    std::cout<<sizeof arr<<" = sizeof arr\n";//输出指针长度    for (int i=0;i<n;i++)        total=total+arr[i];//传递的指针可当做数组名使用    return total;}//P7.7#include <iostream>const int Max =5;int fill_array(double ar[],int limit);//填充数组函数，返回输入的个数void show_array(const double ar[],int n);//打印函数，无返回值void revalue(double r,double ar[],int n);//修改数组函数，直接修改数组无返回值int main(){    using namespace std;    double properties[Max];//定义一个数组记录财产    int size=fill_array(properties,Max);//将实际输出的元素数赋值到size    show_array(properties,size);//打印size个财产    if (size>0)    {        cout<<"Enter revaluation factor: ";        double factor;//输入重新评估因子用于修改数组中的值        while (!(cin>>factor))//输入失败检测模块        {            cin.clear();            while (cin.get()!='\n')                continue;            cout<<"Bad input;please enter a number: ";        }        revalue(factor,properties,size);//调用修改数组函数        show_array(properties,size);//显示修改后的数组函数    }    cout<<"Done.\n";    cin.get();//光标浮动以等待输入    cin.get();    return 0;}int fill_array(double ar[],int limit){    using namespace std;    double temp;    int i;    for (i=0;i<limit;i++)    {        cout<<"Enter value#"<<(i+1)<<": ";        cin>>temp;//读取并写入数组        if (!cin)//输入失败检测模块        {            cin.clear();            while (cin.get()!='\n')                continue;            cout<<"Bad input;input  process terminated.\n";            break;        }        else if (temp<0)//输入负数跳出读取            break;        ar[i]=temp;//如果非负则赋值成功    }    return i;}void show_array(const double ar[],int n){    using namespace std;    for (int i=0;i<n;i++)    {        cout<<"Property #"<<(i+1)<<": $";//循环打印数组        cout<<ar[i]<<endl;    }}void revalue(double r,double ar[],int n){    for (int i=0;i<n;i++)        ar[i]*=r;//和修改因子相乘后重新赋值}//P7.8#include <iostream>const int ArSize=8;int sum_arr(const int * begin,const int * end);//定义数组区别函数，用指针区间传递参数int main(){    using namespace std;    int cookies[ArSize] {1,2,4,8,16,32,64,128};    int sum=sum_arr(cookies,cookies+ArSize);//区间为1~ArSize    cout<<"Total cookies eaten: "<<sum<<endl;    sum=sum_arr(cookies,cookies+3);//传递参数指出数组只有三个元素从而计算前三者总和    cout<<"First three eaters ate "<<sum<<" cookies.\n";    sum=sum_arr(cookies+4,cookies+8);//使用指针区间指定后四个元素    cout<<"Last four eaters ate "<<sum<<" cookies.\n";    return 0;}int sum_arr(const int * begin,const int * end){    const int * pt;    int total=0;    for (pt=begin;pt!=end;pt++)//end为最后一个元素的后面一个位置        total+=*pt;    return total;}//P7.9#include <iostream>unsigned int c_in_str(const char* str,char ch);//也可使用const char str[]int main(){    using namespace std;    char mmm[15]="minimum";    char* wail="ululate";//显式指针赋值    unsigned int ms=c_in_str(mmm,'m');//指针参数和特征字符参数    unsigned int us=c_in_str(wail,'u');    cout<<ms<<" m characters in "<<mmm<<endl;    cout<<us<<" u characters in "<<wail<<endl;    return 0;}unsigned int c_in_str(const char* str,char ch){    unsigned int count=0;    while (*str)//*str表示的第一个字符，不为空值符就继续循环直到'\0'    {        if (*str==ch)            count++;        str++;//移动指针继续指向下一个字符    }    return count;}//P7.10#include <iostream>char* buildstr(char c,int n);//返回指针的函数声明int main(){    using namespace std;    int times;    char ch;    cout<<"Enter a character: ";    cin>>ch;    cout<<"Enter a integer: ";    cin>>times;    char* ps=buildstr(ch,times);    cout<<ps<<endl;    delete [] ps;//释放子函数new出的char*指针    ps=buildstr('+',20);    cout<<ps<<"-DONE-"<<ps<<endl;    delete [] ps;    return 0;}char* buildstr(char c,int n){    char* pstr=new char[n+1];//创建指针指向次数+1，因为结尾是'\0'    pstr[n]='\0';//设置结尾    while (n-->0)//n减到0        pstr[n]=c;//将字符c的值赋值给数组中各元素位置    return pstr;//返回字符串指针，new出来的地址}//P7.11#include <iostream>struct travel_time{    int hours;    int mins;};const int Mins_per_hr=60;//1小时=60分travel_time sum(travel_time t1,travel_time t2);//返回结构的函数原型声明，接收2个结构参数void show_time(travel_time t);//显示结构，接收1个结构参数int main(){    using namespace std;    travel_time day1={5,45};//注意结构不用()用{}    travel_time day2={4,55};    travel_time trip=sum(day1,day2);//结构赋值    cout<<"Two_day total: ";    show_time(trip);    travel_time day3={4,32};    cout<<"Three-day total: ";    show_time(sum(trip,day3));    return 0;}travel_time sum(travel_time t1,travel_time t2){    travel_time total;    total.mins=(t1.mins+t2.mins)%Mins_per_hr;//取模获得剩余分钟数    total.hours=t1.hours+t2.hours+(t1.mins+t2.mins)/Mins_per_hr;//除法获得小时数    return total;}void show_time(travel_time t){    using namespace std;    cout<<t.hours<<" hours, "                 <<t.mins<<" minutes\n";}//P7.12#include <iostream>#include <cmath>struct polar//极坐标结构{    double distance;    double angle;};struct rect//直角坐标结构{    double x;    double y;};polar rect_to_polar(rect xypos);//直角转为极坐标void show_polar(polar dapos);//显示极坐标int main(){    using namespace std;    rect rplace;//声明两个结构以存储输入的数据    polar pplace;    cout<<"Enter the x and y value: ";    while (cin>>rplace.x>>rplace.y)//连续使用cin可行，且忽略空格等    {        pplace=rect_to_polar(rplace);//结果赋值给第二个结构        show_polar(pplace);//显示        cout<<"Next two numbers (q to quiit): ";    }    cout<<"Done.\n";    return 0;}polar rect_to_polar(rect xypos){    using namespace std;    polar answer;    answer.distance=sqrt(xypos.x*xypos.x+xypos.y*xypos.y);    answer.angle=atan2(xypos.y,xypos.x);//y/x计算arctan    return answer;//返回结构}void show_polar(polar dapos){    using namespace std;    const double Rad_to_deg=57.29577951;//弧度转换为度数的常数因子    cout<<"Distance = "<<dapos.distance;    cout<<",angle = "<<dapos.angle*Rad_to_deg;    cout<<" degrees\n";}//P7.13#include <iostream>#include <cmath>struct polar//极坐标结构{    double distance;    double angle;};struct rect//直角坐标结构{    double x;    double y;};void rect_to_polar(const rect* pxy,polar* pda);//传递指针，第二个需要修改故不constvoid show_polar(const polar* pda);//显示极坐标int main(){    using namespace std;    rect rplace;//声明两个结构以存储输入的数据    polar pplace;    cout<<"Enter the x and y value: ";    while (cin>>rplace.x>>rplace.y)//连续使用cin可行，且忽略空格等    {        rect_to_polar(&rplace,&pplace);//结果赋值给第二个结构        show_polar(&pplace);//显示        cout<<"Next two numbers (q to quiit): ";    }    cout<<"Done.\n";    return 0;}void rect_to_polar(const rect* pxy,polar* pda){    using namespace std;    pda->distance=sqrt(pxy->x*pxy->x+pxy->y*pxy->y);//指针使用->来控制成员    pda->angle=atan2(pxy->y,pxy->x);}void show_polar(const polar* pda){    using namespace std;    const double Rad_to_deg=57.29577951;//弧度转换为度数的常数因子    cout<<"Distance = "<<pda->distance;    cout<<",angle = "<<pda->angle*Rad_to_deg;    cout<<" degrees\n";}//P7.14#include <iostream>#include <string>using namespace std;const int SIZE=5;void display(const string sa[],int n);//可写为string* saint main(){    string list[SIZE];    cout<<"Enter your "<<SIZE<<"favorite astronomical sights: \n";    for (int i=0;i<SIZE;i++)    {        cout<<i+1<<": ";        getline(cin,list[i]);//抽取整行    }    cout<<"Your list:\n";    display(list,SIZE);//调用显示模块    return 0;}void display(const string sa[],int n)//传递数组指针和容量参数n{    for (int i=0;i<n;i++)        cout<<i+1<<": "<<sa[i]<<endl;}//P7.15#include <iostream>#include <array>#include <string>const int Seasons=4;const std::array<std::string,Seasons> Snames=        {"Spring","Summer","Fall","Winter"};void fill(std::array<double,Seasons> *pa);void show(std::array<double,Seasons> da);int main(){    std::array<double,Seasons> expenses;    fill(&expenses);//传递地址指针效率高但是看起来复杂    show(expenses);//传递实体效率低下    return 0;}void fill(std::array<double,Seasons> *pa){    using namespace std;    for (int i=0;i<Seasons;i++)    {        cout<<"Enter "<<Snames[i]<<" expenses: ";        cin>>(*pa)[i];//此处括号必不可少    }}void show(std::array<double,Seasons> da){    using namespace std;    double total=0.0;    cout<<"\nEXPENSES\n";    for (int i=0;i<Seasons;i++)    {        cout<<Snames[i]<<": $"<<da[i]<<endl;        total+=da[i];//求和    }    cout<<"Total Expenses: $"<<total<<endl;}//P7.16#include <iostream>void countdown(int n);int main(){    countdown(4);    return 0;}void countdown(int n){    using namespace std;    cout<<"Counting down……"<<n<<" n at "<<&n<<endl;    if (n>0)        countdown(n-1);//递归递减    cout<<n<<":Kaboom!"<<" n at "<<&n<<endl;//逆向退出程序队列故反向输出}//P7.17#include <iostream>const int Len=66;const int Divs=6;void subdivide(char ar[],int low,int high,int level);int main(){    char ruler[Len];    int i;    for (i=1;i<Len-2;i++)        ruler[i]=' ';//中间元素全部填充空格    ruler[Len-1]='\0';//结尾处填充结束的\0    int max=Len-2;//数组\0前的最后一个元素    int min=0;//数组第一个元素    ruler[min]=ruler[max]='|';//首尾填充|    std::cout<<ruler<<std::endl;    for (i=1;i<=Divs;i++)//一下循环ivs次    {        subdivide(ruler,min,max,i);        std::cout<<ruler<<std::endl;        for (int j=1;j<Len-2;j++)            ruler[j]=' ';//每次均重新填充空格再继续下一次循环    }    return 0;}void subdivide(char ar[],int low,int high,int level){    if (0==level)        return;//返回到主函数处继续执行    int mid=(high+low)/2;//求出中间元素的位置数    ar[mid]='|';//将中间这个位置填充|    subdivide(ar,low,mid,level-1);//继续调用递归，但是level-1    subdivide(ar,mid,high,level-1);//后半部分同理}//P7.18#include <iostream>double betsy(int);double pam(int);void estimate(int lines,double (*pf)(int));//声明了函数指针//(*pf)等同函数名效果，两者用法一致；且因历史原因，pf等价于(*pf)int main(){    using namespace std;    int code;    cout<<"How many lines of code do you need? ";    cin>>code;    cout<<"Here's Betsy's estimate:\n";    estimate(code,betsy);//调用函数指针betsy，函数名即地址，可传递    cout<<"Here's Pam's estimate:\n";    estimate(code,pam);    return 0;}void estimate(int lines,double (*pf)(int)){    using namespace std;    cout<<lines<<" lines will take ";    cout<<(*pf)(lines)<<" hour(s)\n";//函数指针调用来计算line}double betsy(int lns){    return 0.05*lns;}double pam(int lns){    return 0.03*lns+0.0004*lns*lns;}//P7.19 R#include <iostream>const double* f1(const double ar[],int n);const double* f2(const double [],int n);const double* f3(const double *,int n);//以上3种函数声明是完全相同的效果int main(){    using namespace std;    double av[3] {1112.3,1542.6,2227.9};    const double *(*p1) (const double *,int)=f1;//定义函数指针p1，初始化指向f1    auto p2=f2;//自动推导来自定义初始化p2，指向f2    cout<<"Using pointers to functions:\n";    cout<<"Address Value\n";    cout<<(*p1)(av,3)<<": "<<*(*p1)(av,3)<<endl;    //第一个函数调用返回double*地址，第二个解除引用将返回指向的具体double值    cout<<p2(av,3)<<": "<<*p2(av,3)<<endl;    //p2和(*p2)在函数调用时是完全等价的(C++规定)，解除只需同样左加*即可    const double *(*pa[3])(const double *,int) {f1,f2,f3};    //pa是一个数组，它的元素是指针，且这些指针是函数指针，分别指向f1,f2,f3    //这些函数指针的返回类型是double*    auto pb=pa;//声明同样类型的数组    cout<<"\nUsing an array of pointers to function:\n";    cout<<"Address Value\n";    for (int i=0;i<3;i++)        cout<<pa[i](av,3)<<": "<<*pa[i](av,3)<<endl;    cout<<"\nUsing a pointer to pointer to a funtion:\n";    cout<<"Address Value\n";    for (int i=0;i<3;i++)        cout<<pb[i](av,3)<<": "<<*pb[i](av,3)<<endl;    cout<<"\nUsing pointer to an array of pointers:\n";    cout<<"Address Value\n";    auto pc=&pa;//指向整个数组的指针，也就是指向数组指针的指针    cout<<(*pc)[0](av,3)<<": "<<*(*pc)[0](av,3)<<endl;    const double *(*(*pd)[3])(const double *,int)=&pa;    //pd是一个指针，且是一个指向数组的指针    //而数组的元素也是指针，且是函数指针，返回double*    const double * pdb=(*pd)[1](av,3);//pd是pa的地址，故(*pd)就是数组名    cout<<pdb<<": "<<*pdb<<endl;//前者是函数返回的地址，后者是函数的实际返回值    cout<<(*(*pd)[2])(av,3)<<": "<<*(*(*pd)[2])(av,3)<<endl;    //数组元素(*pd)[2]是一个函数指针，解除引用后是函数调用，返回地址    //后者再次解除引用就获得函数实际返回值    return 0;}const double* f1(const double ar[],int n){    return ar;}const double* f2(const double ar[],int n){    return ar+1;//指针右移到下1个数组元素}const double* f3(const double ar[],int n){    return ar+2;//指针右移到下2个数组元素}//PP7.13.1#include <iostream>void show();double thpjs(double x,double y);double n1,n2;int main(){    using namespace std;    show();//调用函数不加前面的返回值类型    while (n1!=0&&n2!=0)    {        double result=thpjs(n1,n2);        cout<<"Result of your input: "<<result<<endl;        show();    }    cout<<"wrong input!";    return 0;}double thpjs(double x,double y)//计算函数{    return 2.0*x*y/(x+y);}void show()//读取数据{    using namespace std;    cout<<"Please enter a number: ";    cin>>n1;    cout<<"Please enter another number: ";    cin>>n2;}//PP7.13.2#include <iostream>int score_input(double *,int);double score_average(const double *,int);void score_show(const double *,int,double);//务必注意const必须全部到位！const int ArSize=10;int main(){    using namespace std;    double score_list[ArSize] {0};//初始化成绩数组    int realsize=score_input(score_list,ArSize);//获取数据同时返回实际输入的值    double averagex=score_average(score_list,realsize);//调用函数获取数组平均值    score_show(score_list,realsize,averagex);//显示函数    return 0;}int score_input(double arr[],int limit){    using namespace std;    double temp=0;//输入安全检测临时变量    int i;    for (i=0;i<limit;i++)    {        cout<<"Please Enter score#"<<i+1<<": ";        cin>>temp;        if (!cin)//异常处理模块        {            cin.clear();            while (cin.get()!='\n')//注意此处是cin.get()                continue;            cout<<"Bad input，over.\n";            break;        }        if (temp<0)//输入无效跳出            break;        arr[i]=temp;//有效则赋值    }    return i;//返回实际输入的个数}double score_average(const double arr[],int limit)//注意const{    double sum=0;    for (int i=0;i<limit;i++)    {        sum+=arr[i];    }    return sum/limit;}void score_show(const double arr[],int limit,double v){    using namespace std;    cout<<"Score list: ";    for (int i=0;i<limit;i++)    {        cout<<arr[i]<<" ";    }    cout<<"\nAverage score: "<<v<<endl;}//PP7.13.3#include <iostream>const int ArSize=40;struct box{    char maker[ArSize];    float height;    float width;    float length;    float volume;};box input_real_value(box rv);//按实值传递读取输入box show_real_value(box rv);//按实值传递显示void input_pointer(box* spr);//按指针传递读取输入void show_pointer(const box* spr);//按指针传递显示int main(){    using namespace std;    box xv1;    xv1=input_real_value(xv1);//读取数据到xv1    show_real_value(xv1);//显示读入的数据    box* xv2=new box;//指针指向new出的box结构    input_pointer(xv2);//读取输入到指针指向的结构    show_pointer(xv2);    delete xv2;//勿忘    return 0;}box input_real_value(box rv){    using namespace std;    cout<<"Please enter the maker:";    cin>>rv.maker;    cout<<"Please enter the height,width,length: ";    cin>>rv.height>>rv.width>>rv.length;//数据可以连续读取    rv.volume=rv.height*rv.width*rv.length;//体积计算    return rv;}box show_real_value(box rv){    using namespace std;    cout<<"Maker: "<<rv.maker<<endl;    cout<<"Height,width,length: "<<rv.height        <<" "<<rv.width<<" "<<rv.length<<" "<<endl;    cout<<"Volume: "<<rv.volume<<endl;}void input_pointer(box* spr){    using namespace std;    cout<<"Please enter the maker:";    cin>>spr->maker;    cout<<"Please enter the height,width,length: ";    cin>>spr->height>>spr->width>>spr->length;//指针式连续读取    spr->volume=spr->height*spr->width*spr->length;}void show_pointer(const box* spr){    using namespace std;    cout<<"Maker: "<<spr->maker<<endl;    cout<<"Height,width,length: "<<spr->height        <<" "<<spr->width<<" "<<spr->length<<" "<<endl;    cout<<"Volume: "<<spr->volume<<endl;}//PP7.13.4#include <iostream>long double probability(unsigned field_numbers,unsigned picks,double extr);int main(){    using namespace std;    double total,choices,extra;    long double pro;    cout<<"Enter field_numbers，the number of picks allowed and extra_number:\n";    cout<<"Of course,'q' to quit."<<endl;    while ((cin>>total>>choices>>extra)&&choices<=total)        //同时读取三个参数    {        pro=probability(total,choices,extra);        cout<<"Input is ok.\n";        break;    }    cout<<"Probability to win top-Money is: "<<pro<<endl;    cout<<"Bye\n";    return 0;}long double probability(unsigned field_numbers,unsigned picks,double extr)//形参{    long double result=1.0;    long double n;//提前定义局部变量    unsigned p;    for (n=field_numbers,p=picks;p>0;n--,p--)        result=result*n/p;//利用连乘实现计算且避免中间数过大    result=result*(1/extr);    return result;//返回结果}//PP7.13.5#include <iostream>long long int n_multiplication(int n);int main(){    using namespace std;    cout<<"Enter the number: （q to quit.）";    int n_number;    while (cin>>n_number)    {        long long int result=n_multiplication(n_number);        cout<<n_number<<"!= "<<result<<endl;        cout<<"Next number: ";    }    cout<<"Done.\n";    return 0;}long long int n_multiplication(int n){    using namespace std;    long long int RST;    if (n>0)        RST=n*n_multiplication(n-1);//递归关键核心    else        RST=1;    return RST;}//PP7.13.6#include <iostream>int Fill_array(double arr[],int limit);void show_array(const double [],int limit);void reverse_array(double *,int limit);const int ArSize=10;int main(){    using namespace std;    double z_array[ArSize];    int realvalue=Fill_array(z_array,ArSize);    show_array(z_array,realvalue);    reverse_array(z_array,realvalue);    show_array(z_array,realvalue);    reverse_array(z_array+1,realvalue-2);//指针右移一个元素以及长度缩短两个元素    show_array(z_array,realvalue);    return 0;}int Fill_array(double arr[],int limit){    using namespace std;    double temp;    int i;    for (i=0;i<limit;i++)    {        cout<<"Please enter a number: ";        if (cin>>temp)            arr[i]=temp;        else        {            cin.clear();            while (cin.get()!='\n')                continue;            cout<<"Bad input!\n";            break;        }    }    return i;}void show_array(const double arr[],int limit){    using namespace std;    cout<<"Numbers: ";    for (int i=0;i<limit;i++)        cout<<arr[i]<<" ";    cout<<endl;}void reverse_array(double arr[],int limit){    double swap;    int i;    for (i=0;limit-->i;i++)//关键！交换不会反转的核心    {        swap=arr[limit];//经典交换模型        arr[limit]=arr[i];        arr[i]=swap;    }}//PP7.13.7#include <iostream>const int Max =5;double* fill_array(double ar[],int limit);//填充数组函数，返回实际数组末尾指针void show_array(const double *,const double *);void revalue(double r,double *,double *);int main(){    using namespace std;    double properties[Max];//定义一个数组记录财产    double* size=fill_array(properties,Max);//获取返回的数组指针    show_array(properties,size);    if (size>0)    {        cout<<"\n\nEnter revaluation factor:";        double factor;//输入重新评估因子用于修改数组中的值        while (!(cin>>factor))//输入失败检测模块        {            cin.clear();            while (cin.get()!='\n')                continue;            cout<<"Bad input;please enter a number: ";        }        revalue(factor,properties,size);//调用修改数组函数        show_array(properties,size);//显示修改后的数组函数    }    cout<<"\n\nDone.\n";    cin.get();//光标浮动以等待输入    return 0;}double* fill_array(double ar[],int limit){    using namespace std;    double temp;    int i;    for (i=0;i<limit;i++)    {        cout<<"Enter value#"<<(i+1)<<": ";        cin>>temp;//读取并写入数组        if (!cin)//输入失败检测模块        {            cin.clear();            while (cin.get()!='\n')                continue;            cout<<"Bad input;input  process terminated.\n";            break;        }        else if (temp<0)//输入负数跳出读取            break;        ar[i]=temp;//如果非负则赋值成功    }    double* ip=&ar[i];    return ip;}void show_array(const double* a,const double* b){    using namespace std;    cout<<"\nProperty: $";    for (a;a!=b;a++)//注意指针的条件判断方式    {        cout<<*a<<" ";    }}void revalue(double r,double* a,double* b){    for (a;a!=b;a++)        (*a)*=r;}//PP7.13.8.a#include <iostream>const int Seasons=4;const char* Sname[Seasons] {"Spring","Summer","Fall","Winter"};void fill(double*);void show(double*);int main(){    double expenses[Seasons] {0};    fill(expenses);//传递指针    show(expenses);    return 0;}void fill(double arr[]){    using namespace std;    for (int i=0;i<Seasons;i++)    {        cout<<"Enter "<<Sname[i]<<" expenses: ";        cin>>arr[i];//此处括号必不可少    }}void show(double arr[]){    using namespace std;    double total=0.0;    cout<<"\nEXPENSES\n";    for (int i=0;i<Seasons;i++)    {        cout<<Sname[i]<<": $"<<arr[i]<<endl;        total+=arr[i];//求和    }    cout<<"Total Expenses: $"<<total<<endl;}//PP7.13.8.b R#include <iostream>//细心再细心啊！！const int Seasons=4;struct expense_s{    double expense_arr[Seasons] {0};};//结构定义在函数原型前，避免函数原型声明无效const char* Sname[Seasons] {"Spring","Summer","Fall","Winter"};expense_s fill(expense_s t);void show(const expense_s* t1);int main(){    expense_s sear;    sear=fill(sear);//传递结构    std::cout<<sear.expense_arr[2];    show(&sear);//传递结构指针    return 0;}expense_s fill(expense_s t1){    using namespace std;    for (int i=0;i<Seasons;i++)    {        cout<<"Enter "<<Sname[i]<<" expenses: ";        cin>>t1.expense_arr[i];//结构式存储    }    return t1;//传递结构记得返回！！！}void show(const expense_s* t1){    using namespace std;    double total=0.0;    cout<<"\nEXPENSES\n";    for (int i=0;i<Seasons;i++)    {        cout<<Sname[i]<<": $"<<t1->expense_arr[i]<<endl;        total+=t1->expense_arr[i];//求和    }    cout<<"Total Expenses: $"<<total<<endl;}//PP7.13.9#include <iostream>using namespace std;const int SLEN=30;struct student{    char fullname[SLEN];    char hobby[SLEN];    int opplevel;};int getinfo(student pa[],int n);void display1(student st);void display2(const student* ps);void display3(const student pa[],int n);int main(){    cout<<"Enter calss size: ";    int class_size;    cin>>class_size;    while (cin.get()!='\n')        continue;    student* ptr_stu=new student[class_size];    int entered=getinfo(ptr_stu,class_size);    for (int i=0;i<entered;i++)    {        display1(ptr_stu[i]);        display2(&ptr_stu[i]);    }    display3(ptr_stu,entered);    delete [] ptr_stu;    cout<<"Done\n";    return 0;}int getinfo(student pa[],int n){    using namespace std;    int i;    for (i=0;i<n;i++,pa++)    {        cout<<"Enter #"<<i+1<<" Student name: ";        cin>>pa->fullname;        cout<<"Enter #"<<i+1<<" Student hobby: ";        cin>>pa->hobby;        cout<<"Enter #"<<i+1<<" Student opplevel: ";        cin>>pa->opplevel;        while (!cin)        {            cin.clear();            --i;//输入错误重新返回i值            cout<<"Bad input.\n";            while (cin.get()!='\n')                continue;        }    }    return i;}void display1(student st){    using namespace std;    cout<<"Student name: "<<st.fullname<<endl;    cout<<"Student hobby: "<<st.hobby<<endl;    cout<<"Student opplevel: "<<st.opplevel<<endl;}void display2(const student* ps){    using namespace std;    cout<<"Student name: "<<ps->fullname<<endl;    cout<<"Student hobby: "<<ps->hobby<<endl;    cout<<"Student opplevel: "<<ps->opplevel<<endl;}void display3(const student pa[],int n){    using namespace std;    for (int i=0;i<n;pa++,i++)    {        cout<<"Student name #"<<i+1<<": "<<pa->fullname<<endl;        cout<<"Student hobby #"<<i+1<<": "<<pa->hobby<<endl;        cout<<"Student opplevel #"<<i+1<<": "<<pa->opplevel<<endl;    }}//PP7.13.10 R#include <iostream>const int ArSize=3;double calculate(double n1,double n2,double (*ptr)(double, double));double add(double,double);double minus_n(double,double);double change(double,double);void show_arr(double (*pf[ArSize])(double,double),const char**,double,double);int main(){    using namespace std;    double q=calculate(2.5,10.4,add);    cout<<"Test: q= "<<q<<endl;    double (*pf[ArSize])(double,double){add,minus_n,change};    const char* npa[3] {"add","minus_n","change"};//必须加const！！！    //必须注意npa的类型为char**!!!    //npa为指向第一个字符串的指针！！也即指向指针(字符串)的指针(字符串)    double n1,n2;    cout<<"Enter the pairs numbers: （q to quit.）";    while (cin>>n1>>n2)    {        show_arr(pf,npa,n1,n2);    }    cout<<"Done.\n";    return 0;}double calculate(double n1,double n2,double (*ptr)(double, double)){    return (*ptr)(n1,n2);//此处ptr也可写为(*ptr)}double add(double x,double y){    return x+y;}double minus_n(double x,double y){    return x-y;}double change(double x,double y){    return x*y*0.8;}void show_arr(double (*pf[ArSize])(double,double),const char** pn,double t1,double t2){    using namespace std;    for (int i=0;i<ArSize;i++,pn++)        cout<<*pn<<": "<<pf[i](t1,t2)<<endl;    //pn一接触*就指向字符串，且此处pn++移动的是数组元素间隔}