C ++ Primer Plus Chapter 1 question solution, primer Chapter 2

C ++ Primer Plus Chapter 1 question solution, primer Chapter 2

Chapter C ++ Primer Plus

# Include
 
  
Using namespace std; double fun (double x, double y); int main () {cout <"enter two numbers:"; double a, B; while (cin> a> B & a & B) {cout <fun (a, B) <endl; cout <"enter two numbers: ";} cout <" BYE! "<Endl; return 0;} double fun (double x, double y) {return 2.0 * x * y/(x + y );}
 

7-2

#include 
 
    using namespace std;int input(double *a);void output(double *a, int n);double fun(double *a, int n);int main(){double a[10];int num = input(a);output(a, num);return 0;}int input(double *a){int i;for (i = 0; i < 10; ++i){cin >> a[i];if (a[i] <= 0)break;}return i;}void output(double *a, int n){for (int i = 0; i < n; ++i)cout << a[i] << " ";cout << fun(a, n) << endl;}double fun(double *a, int n){double sum = 0;for (int i = 0; i < n; ++i)sum += a[i];sum /= n;return sum;}
 

7-3

#include 
 
    using namespace std;struct box{char maker[40];float height;float width;float length;float volume;};void fun_a(box a);void fun_b(box *a);int main(){box a = {"Yuuji",10,20,1,22};fun_a(a);fun_b(&a);return 0;}void fun_a(box a){cout << a.maker << endl << a.height << endl << a.width << endl << a.length << endl << a.volume << endl;}void fun_b(box *a){a->volume = a->height * a->width * a->length;cout << a->volume << endl;}
 

7-4

#include 
 
    using namespace std;int main(){double ans = 1;for (int i = 0; i < 5; i++)ans *= (double)(5 - i) / (double)(47 - i);ans *= double(1) / 27;cout << ans << endl;return 0;}
 

7-5

#include 
 
    using namespace std;  long long fun(int n);  int main()  {      int n;      while(cin >> n && n >= 0){          long long ans = 0;          if(!n)              cout << "1" << endl;          else{              ans = fun(n);              cout << ans << endl;          }      }      return 0;  }    long long fun(int n)  {      long long ans = 1;      for( ; n ; --n)          ans *= n;      return ans;  }  
 

7-6

#include 
 
    using namespace std;  int File_array(double *a , int len);  void Show_array(double *a , int len);  void Reverse_array(double *a , int len);  int main()  {      double a[10];      int num = File_array(a , 10);      Show_array(a , num);      Reverse_array(a , num);      Show_array(a , num);      Reverse_array(a + 1 , num - 2);      Show_array(a , num);      return 0;  }    int File_array(double *a , int len)  {      int i;      for(i = 0 ; i < len ; ++ i)          cin >> a[i];      return i;  }    void Show_array(double *a , int len)  {      for(int i = 0 ; i < len ; ++ i)          cout << a[i] << " ";      cout << endl;  }    void Reverse_array(double *a , int len)  {      double temp;      for(int i = 0 ; i < len / 2 ; ++ i)    {          temp = a[i];          a[i] = a[len-1-i];          a[len-1-i] = temp;      }  }  
 

7-7

#include 
 
    using namespace std;double *fill_array(double *a);void show_array(double *a, double *b);void revalue(double r, double *a, double *b);int main(){double a[5];double *e = fill_array(a);show_array(a, e);revalue(0.5, a, e);show_array(a, e);return 0;}double *fill_array(double *a){int i = 0;while (cin >> a[i++])if (i == 5)break;return &a[i];}void show_array(double *a, double *b){while (a != b){cout << *a << " ";++a;}cout << endl;}void revalue(double r, double *a, double *b){while (a != b){(*a) *= r;++a;}}
 

7-8

A

# Include
 
  
Using namespace std; void fill_array (double * a, int len); void show_array (double * a, int len, const char ** p); // char * p is a string, the string array is char ** pint main () {const char * p [4] = {"Spring", "Summer", "Fall", "Winter "}; double a [4]; fill_array (a, 4); show_array (a, 4, p); return 0;} void fill_array (double * a, int len) {for (int I = 0; I <len; ++ I) cin> a [I];} void show_array (double * a, int len, const char ** p) {for (int I = 0; I <len; ++ I) cout <* (p + I) <"\ t "; cout <endl; for (int I = 0; I <len; ++ I) cout <a [I] <"\ t"; cout <endl ;}
 

B

#include 
 
    using namespace std;  struct money{      double a[4];  };  void fill_array(money *m , int len);  void show_array(money *m , int len , char **p);  int main()  {      money t;      char *p[4] = {"Spring" , "Summer" ,  "Fall"  , "Winter"};      fill_array(&t , 4);      show_array(&t , 4 , p);      return 0;  }    void fill_array(money *m , int len)  {      for(int i = 0 ; i < len ;  ++ i)          cin >> m->a[i];  }    void show_array(money *m , int len , char **p)  {      for(int i = 0 ; i < len ; ++ i)          cout << *(p + i) << "\t";      cout << endl;      for(int i = 0 ; i < len ; ++ i)          cout << m->a[i] << "\t";      cout << endl;  }  
 

7-9

It's too troublesome to write again when you are free.

7-10

    #include 
 
              double calculate(double a, double b, double (*pf)(double a, double b));      double add(double a, double b);      double max(double a, double b);      double min(double a, double b);            int main()      {          double a, b;          double (*pf[3])(double a, double b);          pf[0] = add;          pf[1] = max;          pf[2] = min;          while(std::cin >> a >> b)              for(int i = 0 ; i < 3 ; ++i)                  std::cout << (*pf[i])(a, b) << std::endl;          return 0;      }            double calculate(double a, double b, double (*pf)(double a, double b))      {          return (*pf)(a, b);      }            double add(double a, double b)      {          return a + b;      }            double max(double a, double b)      {          return a > b ? a : b;      }            double min(double a, double b)      {          return a < b? a : b;      }