c++ primer plus 习题答案(2)
p221.8
1 #include<iostream> 2 #include<cstdlib> 3 #include<cstring> 4 using namespace std; 5 const int SLEN = 30; 6 struct student{ 7 char fullname[SLEN]; 8 char hobby[SLEN]; 9 int ooplevel; 10 }; 11 int getinfo(student pa[], int n); 12 void display1(student st); 13 void display2(const student *ps); 14 void display3(const student pa[], int n); 15 16 int main(){ 17 cout << "enter class size:"; 18 int class_size; 19 cin >> class_size; 20 while (cin.get() != '\n') 21 continue; 22 student *ptr_stu = new student[class_size]; 23 int entered = getinfo(ptr_stu, class_size); 24 for (int i = 0; i < entered; i++){ 25 display1(ptr_stu[i]); 26 display2(&ptr_stu[i]); 27 } 28 display3(ptr_stu, entered); 29 delete[]ptr_stu; 30 cout << "done\n"; 31 system("pause"); 32 return 0; 33 } 34 35 int getinfo(student pa[], int n){ 36 int i = 0, count = 0; 37 while (i < n && *pa[i].fullname != '\0'){ 38 cin.getline(pa[i].fullname, SLEN); 39 cin.getline(pa[i].hobby, SLEN); 40 cin >> pa[i].ooplevel; 41 cin.get(); 42 count++; 43 i++; 44 } 45 return count; 46 } 47 48 void display1(student st){ 49 cout << "st.fullname" << st.fullname << 50 endl << "st.hobby" << st.hobby << 51 endl << "st.ooplevel" << st.ooplevel << 52 endl; 53 } 54 55 void display2(const student *ps){ 56 cout << "ps->fullname" << ps->fullname << 57 endl << "ps->hobby" << ps->hobby << 58 endl << "ps->ooplevel" << ps->ooplevel << 59 endl; 60 } 61 62 void display3(const student pa[], int n){ 63 for (int i = 0; i < n; i++){ 64 cout << "pa[i].fullname" << pa[i].fullname 65 << endl << "pa[i].hobby" << pa[i].hobby 66 << endl << "pa[i].ooplevel" << pa[i].ooplevel 67 << endl; 68 } 69 }
p259.2
1 #include<iostream> 2 #include<cstdlib> 3 #include<cstring> 4 using namespace std; 5 struct candybar { 6 char brand[81]; 7 float weight; 8 int calory; 9 }; 10 void assign(candybar &, char br[81]="millennium munch", float w=2.85, int c=350); 11 void show_menu(candybar&); 12 13 int main(){ 14 candybar tasty; 15 assign(tasty); 16 show_menu(tasty); 17 system("pause"); 18 return 0; 19 } 20 21 void assign(candybar &delicious, char br[81], float w , int c){ 22 strcpy(delicious.brand, br); 23 delicious.weight = w; 24 delicious.calory = c; 25 } 26 27 void show_menu(candybar&delicious){ 28 cout << delicious.brand << endl; 29 cout << delicious.weight << endl; 30 cout << delicious.calory << endl; 31 }
p259.4
1 #include<iostream> 2 #include<cstdlib> 3 #include<cctype> 4 using namespace std; 5 struct stringy{ 6 char* str; 7 int ct; 8 }; 9 void set(stringy &, const char*); 10 void show(const stringy &, int times = 1); 11 void show(const char*, int times = 1); 12 13 int main(){ 14 stringy beany; 15 char testing[] = "reality isn't what it used to be."; 16 set(beany, testing); 17 show(beany); 18 show(beany, 2); 19 delete beany.str; 20 testing[0] = 'D'; 21 testing[1] = 'u'; 22 show(testing); 23 show(testing, 3); 24 show("Done!"); 25 system("pause"); 26 return 0; 27 } 28 29 void set(stringy &beany, const char* testing){ 30 int num = strlen(testing); 31 beany.str = new char[num + 1]; 32 strcpy(beany.str, testing); 33 beany.ct = num; 34 } 35 36 void show(const stringy &beany, int times){ 37 for (int i = 0; i < times; i++) 38 cout << beany.str << endl 39 << beany.ct << endl; 40 } 41 42 void show(const char* testing, int times){ 43 for (int i = 0; i < times; i++) 44 cout << testing << endl; 45 }
p260.6
1 #include<iostream> 2 #include<cstdlib> 3 #include<cstring> 4 using namespace std; 5 template<class T> 6 T maxn(T ar[], int num); 7 template<> char *maxn(char *pt[], int num); 8 9 int main(){ 10 int num1[6]; 11 double num2[4]; 12 cout << "enter the member of two array\n"; 13 for (int i = 0; i < 6; i++) 14 cin >> num1[i]; 15 for (int i = 0; i < 4; i++) 16 cin >> num2[i]; 17 int imax = maxn(num1, 6); 18 double dmax = maxn(num2, 4); 19 cout << "imax is" << imax << endl 20 << "dmax is" << dmax << endl; 21 char *str[5]; 22 str[0] = "his eyes came round"; 23 str[1] = "it all seems very unchanged"; 24 str[2] = "which contain of old the pipes"; 25 str[3] = "yes, billy, i know"; 26 str[4] = "will you be please to dine"; 27 char *address = maxn(str, 5); 28 cout << (int*)address << " " << 29 address << endl; 30 system("pause"); 31 return 0; 32 } 33 34 template<class T> 35 T maxn(T ar[], int num){ 36 T max=ar[0]; 37 for (int i = 1; i < num; i++) 38 if (max < ar[i]) 39 max = ar[i]; 40 return max; 41 } 42 43 template<> char *maxn(char *pt[], int num){ 44 int length[5], i; 45 for (i = 0; i < 5; i++) 46 length[i] = strlen(pt[i]); 47 int max = length[0]; 48 for (i = 0; i < 5; i++) 49 if (max < length[i]) 50 max = length[i]; 51 for (i = 0; i < 5; i++) 52 if (max == length[i]) 53 break; 54 return pt[i]; 55 }
