C++ Primer Plus第7章题目题解
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2022-03-23 20:01:19
C++ Primer Plus第7章题目题解
#include
using namespace std;
double fun(double x, double y...
C++ Primer Plus第7章题目题解
#include using namespace std; double fun(double x, double y); int main() { cout << "请输入两个数: "; double a, b; while (cin >> a >> b && a && b) { cout << fun(a, b) << endl; cout << "请输入两个数: "; } 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是字符串,字符串数组就是char **p int 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
太麻烦了,有空再写
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; }
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