链表的应用

C++上周三试毕，题很简单，轻松拿下。最近一直在看Apple Developer上的文档，脑子里尽是ObjC。项目设计第一个题是链表，当初就没学好，跟着网上的tutorials给写出来了。这两天在看《三国演义》，网上订了《史记》和《聊斋志异》，一直都很喜欢读文言文，觉得古代小说很有意思，语言非常精炼。也是因为天天对着满屏幕的英文，有点枯燥了，遂寻汉文而读。

#include <iostream>
#include <string>
#include <iomanip>
#include <cctype>

using namespace std;

struct Buddy {
    string name;
    string sex;
    string age;
    string score;
    struct Buddy *next;
};

int n=0;

// creat a new list START
struct Buddy *creat() {
    struct Buddy *head;
    struct Buddy *p1,*p2;
    n = 0; // reset the amounst of members
    p1 = p2 = (struct Buddy *)new struct Buddy;
    
    cout << setiosflags(ios::left) << setw(15) << "Name" ;
    cout << setw(10) << "Sex" << setw(10) << "Age" << setw(10) << "Score" << endl;
    
    cin >> p1->name >> p1->sex >> p1->age >> p1->score;
    head=NULL; // reset the list whenever creat a new list
    while (p1->name != "0") {
        n++;
        if (n == 1) {
            head = p1;
        }
        else {
            p2->next = p1;
        }
        p2 = p1;
        p1 = (struct Buddy *)new struct Buddy;
        cin >> p1->name >> p1->sex >> p1->age >> p1->score;
    }
    p2->next = NULL;
    return head;
}
// creat a new list END

// print the list START
void print(struct Buddy *head) {
    struct Buddy *p;
    
    p = head;
    if (head != NULL) {
        cout << '\n' << setiosflags(ios::left) << setw(15) << "Name" ;
        cout << setw(10) << "Sex" << setw(10) << "Age" << setw(10) << "Score" << endl;
        do {
            cout << setiosflags(ios::left) << setw(15) << p->name 
                 << setw(10) << p->sex << setw(10) << p->age << setw(10) << p->score << endl;
            p = p->next;
        } while(p != NULL);
    }
    else {
        cout << "Error: List is null." << endl;
    }
}
// print the list END

// delete one member START
struct Buddy *del(struct Buddy *head, string checkingName) {
    struct Buddy *p1,*p2;
    if (head != NULL) {
        p1 = head;
        while (checkingName!=p1->name && p1->next!=NULL) {
            p2 = p1;
            p1 = p1->next;
        }
        if (checkingName == p1->name) {
            if (p1 == head) {
                head = p1->next;
            }
            else {
                p2->next = p1->next;
            }
            cout << checkingName <<" has been deleted."<< endl;
            n--;
        }
        else {
            cout << checkingName <<" is not found." << endl;
        }
    }
    else {
        cout << "Error: List is null." << endl;
    }
    return head;
}
// delete one member END

// insert a member START
struct Buddy *insert(struct Buddy *head, struct Buddy *toInsert) {
    struct Buddy *p0,*p1,*p2;
    p0 = toInsert;
    p1 = head;
    if (head == NULL) {
        head = p0;
        p0->next = NULL;
    }
    else {
        while ((p0->name > p1->name)&&(p1->next!=NULL)) {
            p2 = p1;
            p1 = p1->next;
        }
    }
    if (p0->name <= p1->name) {
        if (head == p1) {
            head = p0;
        }
        else {
            p2->next = p0;
        }
        p0->next = p1;
    }
    else {
        p1->next = p0;
        p0->next = NULL;
    }
    n++;
    return head;
}
// insert a member END


// menu START
void menu() {
    cout << endl;
    cout << "*----------------------------------------*" << endl;
    cout << "|                                        |" << endl;
    cout << "|       (C) Creat a new list.            |" << endl;
    cout << "|       (P) Print the list.              |" << endl;
    cout << "|       (D) Delete one person.           |" << endl;
    cout << "|       (I) Insert a new person.         |" << endl;
    cout << "|       (E) Exit.                        |" << endl;
    cout << "|                                        |" << endl;
    cout << "|       End with four zeros:             |" << endl;
    cout << "|       Just like 0 0 0 0                |" << endl;
    cout << "|                                        |" << endl;
    cout << "*----------------------------------------*" << endl;
    cout << "Enter: ";
}
// menu END
int main(int argc, const char * argv[])
{
    struct Buddy *myBuddy = NULL;
    struct Buddy *toInsert;
    string checkingName;
    char c;
    menu();
inputTheC:
    cin >> c;
    c=toupper(c);
    if (c=='C'||c=='P'||c=='D'||c=='I'||c=='E') {
        if (c!='E') {
            while (c!='E') {
                switch (c) {
                    case 'C':
                        myBuddy=creat();
                        break;
                    case 'P':
                        print(myBuddy);
                        break;
                    case 'D':
                        cout << "Enter the name you want to delete: ";
                        cin >> checkingName;
                        myBuddy = del(myBuddy, checkingName);
                        break;
                    case 'I':
                        cout << '\n' << "Enter the information you want to insert:" << '\n' << endl;
                        toInsert = creat();
                        myBuddy = insert(myBuddy, toInsert);
                        break;
                        
                    default:
                        break;
                }
                menu();
                cin >> c;
                c = toupper(c);
            }
        }
        else {
            cout << "Exited." << endl;
            exit(1);
        }
    }
    else {
        cout << "Enter the correct letter." << endl;
        goto inputTheC;
    }
    return 0;
}