《C++ primer plus》第七章8、9题，编程格式思路纯属个人喜好：

8. 

#include 
     
      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 class 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 ){    int count = 0;    for (int i = 0; i < n; i++)    {        cout << "Please input student's name: ";        cin.getline( pa[i].fullname, SLEN );        if ( strlen(pa[i].fullname) != 0 )        //判断是否为空行        {            count += 1;            cout << "Please input student's hobby: ";            cin.getline( pa[i].hobby, SLEN );            cout << "Please input student's ooplevel: ";            cin >> pa[i].opplevel;            while ( cin.get() != '\n' )                continue;        }        else            break;        }    cout << "In fact we have " << count << " students.\n" << endl;    return count;}void display1( student st ){    cout << st.fullname << '\t' << st.hobby << '\t' << st.opplevel <
      
       fullname << '\t' << ps->hobby << '\t' << ps->opplevel << endl;}void display3( const student pa[ ], int n ){    for (int i = 0; i < n; i++ )    {        cout << pa[i].fullname << '\t' << pa[i].hobby << '\t' << pa[i].opplevel << endl;    }}
      
     

9.

(1) 这里是让用户输入两个数计算或者按q退出：

#include 
     
      using namespace std;double add( double x, double y ){    return x + y;}double calculate ( double x, double y, double (*f)( double , double )  ){    return f( x, y );}int main( ){    double x, y;    cout << "Please input two numbers or end by q: ";    while( (cin >> x >> y ) )    {
    double result = calculate ( x, y, add );        cout << "Result is " << result << endl;        cout << "Please input two numbers or end by q: ";    }    return 0;}
     

(2) 用了一个指向函数的指针数组：

#include 
     
      using namespace std;double add( double x, double y ){    return x + y;}double mlu( double x, double y ){    return x * y;}double calculate ( double x, double y, double (*f)( double , double )  ){    return f( x, y );}int main( ){    double x, y;    double (*pf[2]) ( double, double ) = {add, mlu};    char * cp[2] = {
   "add", "mlu"};    cout << "Please input two numbers or end by q: ";    while( (cin >> x >> y ) )    {        for (int i = 0; i < 2; i++ )            cout << cp[i] << " = " << calculate( x, y, pf[i] ) << endl;        cout << "Please input two numbers or end by q: ";    }    return 0;}