许久之前，在vector读写那篇博客末尾。本人装13说要用C++完成简易的图书馆管理系统。
But, = =期间遇到一个难以攻克的难题。在对vector<Struct>读写时，会出现地址冲突。虽然在stackOverFlow发布过问题，也查找过相关资料。
很不幸运，还是没能解决。 = = 没办法，只是菜鸟。
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但我还是尝试了另一种方法来进行读写操作，在Struct中增加一个toString()方法，不进行二进制读写，直接用输入输出流操作。
Lucky, 终于了结一心结。
下面上代码，注释不多，对sstream（字符串流）不熟悉的，可以查看下C++ Primer相关内容。
1 /*
2 * dataAndAlgorithm homework
3 * A simple student information administration system
4 * windy 2016/09/19
5 */
6 #include "stdafx.h"
7 #include <string>
8 #include <sstream>
9 #include <iostream>
10 #include <fstream>
11
12
13 class Student {
14 public:
15 std::string ID;
16 std::string name;
17 std::string birthday;
18 std::string sex;
19 std::string health;
20 Student(const std::string& _id = "",const std::string& _name = "",const std::string& _birth = "",const std::string& _sex = "",const std::string& _heal ="")
21 :ID(_id),name(_name),birthday(_birth),sex(_sex),health(_heal){}
22 const std::string toString() {
23 return this->ID + " " + this->name + " " + this->birthday + " " + this->sex + " " + this->health + "\n";
24 }
25 void display() {
26 std::cout << "\tID:" << this->ID << "\n"
27 << "\tName:" << this->name << "\n"
28 << "\tBirthday:" << this->birthday << "\n"
29 << "\tSex:" << this->sex << "\n"
30 << "\tHealth:" << this->health << "\n\n";
31
32 }
33 Student& operator = (const Student& t) {
34 ID = t.ID;
35 name = t.name;
36 birthday = t.birthday;
37 sex = t.sex;
38 health = t.health;
39 return *this;
40 }
41 };
42 //create my list
43 class MyList {
44 private:
45 struct _List
46 {
47 Student element;
48 _List* next;
49 _List(const Student& _ele = Student(), _List* _next = NULL):element(_ele), next(_next){}
50 };
51 public:
52 //constructor
53 MyList(){
54 head = NULL;
55 size = 0;
56 }
57 // method add / push_back new node
58 // @return void #insert innformation into the list
59 bool add(const Student& newStud) {
60 if (NULL == this->head) {
61 this->head = new _List(newStud, NULL);
62 size++;
63 return true;
64 }
65 _List* curr = this->head;
66 while (curr->next != NULL) {
67 curr = curr->next;
68 }
69 curr->next = new _List(newStud, NULL);
70 size++;
71 return true;
72 }
73 // method search
74 // @return Student
75 Student& search(const std::string& ID) const{
76 _List* curr = this->head;
77 while (curr) {
78 if (curr->element.ID == ID)
79 return curr->element;
80 curr = curr->next;
81 }
82 return Student(); //return EMPTY student struct
83 }
84 // method erase
85 // @return bool #TURE for erase successfully, or failed.
86 bool erase(const std::string& ID) {
87 if (this->head->element.ID == ID) {
88 _List* tmp = this->head;
89 this->head = this->head->next;
90 delete tmp;
91 return true;
92 }
93 _List* curr = this->head;
94 while (curr != NULL) {
95 if (curr->next->element.ID == ID) {
96 _List* tmp = curr->next;
97 curr->next = tmp->next;
98 delete tmp;
99 return true;
100 }
101 curr = curr->next;
102 }
103 return false;
104 }
105 // method update
106 // @return bool
107 bool update(const std::string& ID){
108 Student& studForUpdate = search(ID);
109 if (studForUpdate.ID != "") {
110 std::cout << "The following is the information of the student." << std::endl;
111 studForUpdate.display();
112
113 std::cout << "Please input the number to choose the Update-Item." << std::endl;
114 std::cout << "\t1:ID" << "\t2:Name" << "\t3:Birthday" << "\t4:Sex" << "\t5:Health" << std::endl;
115 int choice;
116 std::cin >> choice;
117 std::string value;
118 switch (choice)
119 {
120 case 1: {
121 std::cout << "Input new ID." << std::endl;
122 std::cin >> value;
123 studForUpdate.ID = value;
124 }break;
125 case 2: {
126 std::cout << "Input new name." << std::endl;
127 std::cin >> value;
128 studForUpdate.name = value;
129 }break;
130 case 3: {
131 std::cout << "Input new birthday." << std::endl;
132 std::cin >> value;
133 studForUpdate.birthday = value;
134 }break;
135 case 4: {
136 std::cout << "Input new sex." << std::endl;
137 std::cin >> value;
138 studForUpdate.sex = value;
139 }break;
140 case 5: {
141 std::cout << "Input new health." << std::endl;
142 std::cin >> value;
143 studForUpdate.health = value;
144 }break;
145 default:
146 std::cout << "Wrong choice!!!" << std::endl;
147 break;
148 }
149 return true;
150 }
151 else return false;
152 }
153 // method display
154 // @return void
155 void display() {
156 if (NULL == this->head) {
157 std::cout << "No Data!" << std::endl;
158 return;
159 }
160 _List* curr = this->head;
161 while (curr != NULL) {
162 curr->element.display();
163 curr = curr->next;
164 }
165 }
166 // method clear
167 // @return void
168 void clear() {
169 _List* curr = head;
170 while (curr){
171 _List* tmp = curr;
172 curr = curr->next;
173 delete tmp;
174 }
175 }
176 // method sort
177 // return void
178 void sort() {
179 for (int i = 0; i != size; i++) {
180 _List* prev = this->head;
181 _List* curr = prev->next;
182 while (curr != NULL) {
183 if (stringToInt(prev->element.ID) > stringToInt(curr->element.ID)) {
184 Student tmp = prev->element;
185 prev->element = curr->element;
186 curr->element = tmp;
187 }
188 prev = prev->next;
189 curr = curr->next;
190 }
191 }
192 }
193 // method write
194 // @return bool
195 bool write() {
196 std::fstream out("StudentSql.txt", std::ios::out|std::ios::app);
197 if (!out) {
198 std::cerr << "Can‘t open the file.Program exit!" << std::endl;
199 exit(-1);
200 }
201 std::cout << "Writing ... ..." << std::endl;
202 _List* curr = this->head;
203 while (curr != NULL) {
204 out << curr->element.toString();
205 curr = curr->next;
206 }
207 out.close();
208 return true; //std::cout << "Completed!" << std::endl;
209 }
210 // method read
211 // @return bool
212 bool read() {
213 // this->clear();
214 char c;
215 std::cout << " Y to continue, N to cancel " << std::endl;
216 std::cin >> c;
217 if (c == ‘N‘ || c == ‘n‘) return false;
218 std::fstream in("StudentSql.txt",std::ios::in);
219 std::cout << "Reading ... ..." << std::endl;
220 if (!in) {
221 std::cerr << "Can‘t open the file.Program exit!" << std::endl;
222 exit(-1);
223 }
224 std::string line;
225 std::string word;
226 while (std::getline(in, line)) {
227 std::stringstream stream(line);
228 std::string strs[5];
229 int i = 0;
230 while (stream >> word) {
231 strs[i++] = word;
232 }
233 this->add(Student(strs[0], strs[1], strs[2], strs[3], strs[4]));
234 }
235 in.close();
236 return true; //read successfully
237 }
238
239 private:
240 _List* head; //DEFAULT NULL
241 int size;
242 int stringToInt(const std::string& str) { //max 1111 1111 11
243 int cnt = 0;
244 size_t sizeOfStr = str.size() > 10 ? 10 : str.size();
245 int tens = 1;
246 for (size_t i = 0; i != sizeOfStr; i++, tens *= 10) {
247 cnt += tens*(str[sizeOfStr - i - 1] - ‘0‘);
248 }
249 return cnt;
250 }
251 };
252
253 /*
254 * 实现学生健康情况管理的几个操作功能（新建、插入、删除、从文件读取、写入文件和查询、屏幕输出等功能）。
255 * 健康表中学生的信息有学号、姓名、出生日期、性别、身体状况等。
256
257 * 即系统的菜单功能项如下：
258
259 * ------新建学生健康表 get
260 * ------向学生健康表添加新的学生信息 get
261 * ------在健康表删除指定学生的信息（按学号操作） get
262 * ------为某个学生修改身体状况信息（按学号操作） get
263 * ------按学生的学号排序并显示结果 get
264 * ------在健康表中查询学生信息（按学生学号来进行查找） get
265 * ------在屏幕中输出全部学生信息 get
266 * ------从文件中读取所有学生健康表信息 get
267 * ------向文件写入所有学生健康表信息 get
268 * -----退出
269 */
270 void header() {
271 std::cout << " Please input the number to choose a function\n\n"
272 << "\t1:Add " << "\t2:Update" << "\t3:Delete\n"
273 << "\t4:Sort " << "\t5:Search" << "\t6:Display\n"
274 << "\t7:Write " << "\t8:Read " << "\t9:Exit \t10:Clear the screen\n\n";
275 }
276 void switcher() {
277 MyList* studList = new MyList();
278 Student student;
279 while (true)
280 {
281 int i = 0;
282 std::cin >> i;
283 //temperature string value
284 std::string ID;
285 switch (i) {
286 case 1: {
287 std::cout << "Please input the information including /ID /name /birthday /sex /health_state ..." << std::endl;
288 std::cout << "ID..." << std::endl;
289 std::cin >> student.ID;
290 std::cout << "Name..." << std::endl;
291 std::cin >> student.name;
292 std::cout << "Birthday..." << std::endl;
293 std::cin >> student.birthday;
294 std::cout << "Sex..." << std::endl;
295 std::cin >> student.sex;
296 std::cout << "Health state...(Good/Averaged/Bad)" << std::endl;
297 std::cin >> student.health;
298 if (studList->add(student)) std::cout << "Add new student successfully!" << std::endl;
299 else std::cout << "Error adding!" << std::endl;
300 }break;
301 case 2: {
302 std::cout << "Please input the Student-ID." << std::endl;
303 std::cin >> ID;
304 if (studList->update(ID)) std::cout << "Update information successfully!" << std::endl;
305 else std::cout << "Error updating!" << std::endl;
306 }break;
307 case 3: {
308 std::cout << "Please input the Student-ID." << std::endl;
309 std::cin >> ID;
310 if (studList->erase(ID)) std::cout << "Delete information successfully!" << std::endl;
311 else std::cout << "Error deleting!" << std::endl;
312 }break;
313 case 4: {
314 studList->sort();
315 }break;
316 case 5: {
317 std::cout << "Please input the Student-ID." << std::endl;
318 std::cin >> ID;
319 Student tmp = studList->search(ID);
320 if (tmp.ID != " ") tmp.display();
321 else std::cout << "No such student!" << std::endl;
322 }break;
323 case 6: {
324 studList->display();
325 }break;
326 case 7: {
327 if (studList->write()) std::cout << "Writing data successfully!" << std::endl;
328 else std::cout << "Error deleting!" << std::endl;
329 }break;
330 case 8: {
331 // std::cout << "Warning:Reading Data will destrory the data get in the console window\n" << std::endl;
332 if (studList->read()) std::cout << "Reading data successfully!" << std::endl;
333 else std::cout << "Error deleting!" << std::endl;
334 }break;
335 case 9: {
336 std::cout << "Warning:Make sure to write the data before exit!!\n Y to continue N to cancel " << std::endl;
337 char c;
338 std::cin >> c;
339 if (c == ‘N‘ || c == ‘n‘) break;
340 exit(-1);
341 }break;
342 case 10: {
343 system("cls");
344 }break;
345 default:
346 break;
347 }
348 header();
349 }
350 }
351 void doIt() {
352 header();
353 switcher();
354 }
355
356
357 int main()
358 {
359 doIt();
360 system("pause");
361 return 0;
362 }
末尾得点明下，虚数据库并没有检查重复项等功能，当然这属于设计一个数据库的范畴了。
时间： 2024-10-09 07:12:54