c++primer 第八章习题

#include <iostream>
#include <string>
#include <cctype>
#include <cstring>

using namespace std;

//practice 1
void fun_of_p8_1(char *str, int print_times=0){
    cout<<"string: "<<str<<", print times: "<<print_times<<endl;
    if (print_times>1){
        print_times--;
        fun_of_p8_1(str, print_times);
    }
}

void p8_1(void){
    char str[128];
    int print_times=0;
    cout<<"Enter what string you want to print: ";
    cin.getline(str, 128);
    cout<<"Enter the time you want to print: ";
    cin>>print_times;
    
    cout<<"two paramters: "<<endl;
    fun_of_p8_1(str, print_times);
    cout<<"one parameters: "<<endl;
    fun_of_p8_1(str);
}

//practice 2
struct CandyBar{
    char company[128];
    double weight;
    int heat;
};
void print_CandyBar(const CandyBar &candybar){
    cout<<"candy bar company: "<<candybar.company<<endl;
    cout<<"candy bar weight: "<<candybar.weight<<endl;
    cout<<"candy bar heat: "<<candybar.heat<<endl;
}

void fill_CandyBar(struct CandyBar &candybar, char *company, double weight, int heat){
    strcpy(candybar.company, company);
    candybar.weight=weight;
    candybar.heat=heat;
}
void p8_2(void){
    struct CandyBar candybar={""};
    char company[128];
    double weight=0.0;
    int heat=0;
    
    cout<<"enter the company of candybar: ";
    cin.getline(company, 128);
    cout<<"enter the weight of candybar: ";
    cin>>weight;
    cout<<"enter the heat of candybar: ";
    cin>>heat;
    
    fill_CandyBar(candybar, company, weight, heat);
    print_CandyBar(candybar);
    
    return ;
}
//practice 3
void p8_3(void){
    string input;
    
    cout<<"enter a string (q to quit): ";
    cin>>input;
    while (input[0]!='q') {
           for(size_t i=0;i<input.length();i++){
               input[i]=toupper(input[i]);
           }
        cout<<input<<endl;
        cout<<"next string (q to quit): ";
        cin>>input;
    }
}
//practice 4
struct stringy{
    char *str;
    int ct;
};
void set(struct stringy &in_stringy, char *in_string){
    int string_length=strlen(in_string);
    in_stringy.str=new char(string_length+1);
    strcpy(in_stringy.str, in_string);
    in_stringy.ct=string_length;
}

void show(const struct stringy &in_string, int print_time=1){
    for (int i=0; i<print_time; i++) {
        cout<<"member string of struct stringy: "<<in_string.str<<endl;
    }
}
void show(const char *str, int print_time=1){
    for(int i=0;i<print_time;i++){
        cout<<"print char string: "<<str<<endl;
    }
}

int p8_4(void){
    stringy beany;
    char testing[]="reality is not what it used to be.";
    set(beany, testing);
    show(beany);
    show(beany, 2);
    testing[0]='D';
    testing[1]='u';
    show(testing);
    show(testing, 3);
    show("Done");
    return 0;
}

//main
int main(int argc, char**argv){
    p8_4();
    
    while (cin.get());
}

//practice 5
template<typename T>
T max5(T in_array[])
{
    T max = in_array[0];
    for (size_t i=0; i<5; i++) {
        if(max<in_array[i]){
            max=in_array[i];
        }
    }
    return max;
}
void p8_5(void){
    int int_array[5]={1,2,3,4,5};
    double double_array[5]={1.1,2.2,3.3,4.4,5.5};
    
    int int_array_max=max5(int_array);
    double double_array_max=max5(double_array);
    
    cout<<int_array_max<<endl;
    cout<<double_array_max<<endl;
    
}

//practice 6
template<typename T>
T maxn(T in_array[], int array_size){
    T max=in_array[0];
    for (int i=0; i<array_size; i++) {
        if (max<in_array[i]) {
            max=in_array[i];
        }
    }
    return max;
}
template<>const char * maxn(const char *int_str[], int n){
    const char * str=int_str[0];
    for (int i=0;i<n; i++) {
        if (strlen(str)<strlen(int_str[i])) {
            str=int_str[i];
        }
    }
    return str;
}
void p8_6(void){
    int int_array[6] = { 43, 235, 54, 232, 123, 65 };
    double double_array[4] = { 32.1, 453.2, 53.3, 67.4 };
    const char * str_array[5] = { "Hello Jimmy!", "Hello World!", "ABCDEFG,HIJKLMN", "Today is a goood day!", "C++ Primer Plus!" };
    
    int int_array_max=maxn(int_array, 6);
    double double_array_max=maxn(double_array, 4);
    const char * length_max_str=maxn(str_array, 5);
    
    cout<<int_array_max<<endl;
    cout<<double_array_max<<endl;
    cout<<length_max_str<<endl;
    
}

//practice 7
template <typename T>
T SumArray(T in_arr[], int n);

template<typename T>
T SumArray(T *arr[], int n);

struct debts{
    char name[20];
    double amount;
};
int p8_7(void)
{
    int thing[6] = { 13, 31, 103, 301, 310, 130 };
    int int_sum = 0;
    struct debts mr_E[3] =
    {
        {"Ima Wolfe", 2400.0},
        {"Ura Foxe", 1300.0},
        {"Iby Stout", 1800.0}
    };
    double *pd[3];
    double double_sum = 0.0;
    
    for (size_t i = 0; i < 3; i++)
    {
        pd[i] = &mr_E[i].amount;
    }
    
    int_sum = SumArray(thing, 6);
    double_sum = SumArray(pd, 3);
    
    cout << "Sum of int array: " << int_sum << endl;
    cout << "Sum of double* array: " << double_sum << endl;
    
    return 0;
}