C++自学精简教程 目录(必读)

该作业是 作业 学生通讯录管理：文本文件增删改查（C++版本） 的C 语言版本。

具体的作业题目描述，要求，可以参考 学生通讯录管理：文本文件增删改查（C++版本）。

为何要有这个作业

这个作业同时提供C++和C两个版本，是我精心设计的。

很多人不清楚到底C和C++ 有何区别。

这两个作业的输入一模一样，输出也一模一样。

本文为了对比C和C++两种语言，特意使用C重新原样实现了一遍。

让学生对面向对象和面向过程的的不同有一个直观的认识。

启动代码

下面是C 语言版本的代码完整实现，比C++ 版本多了10行代码：

#include <stdio.h>
#include <string.h>
#include <assert.h>
#define bool int
#define true 1
#define false 0
#define NAME_LENGTH 30
#define TEL_LENGTH 15typedef struct _Person
{int m_id;char m_name[NAME_LENGTH];char m_tel[TEL_LENGTH];
} Person;
void print_person(Person* person)
{//-表示左对齐，默认右对齐printf("%-5d%-15s%-20s\n", person->m_id, person->m_name, person->m_tel);
}
//返回 bool 表示读取到了文件的末尾
bool read_person(FILE* fp, Person* person)
{bool result = false;if (fscanf(fp, "%d %s %s", &person->m_id, &person->m_name, &person->m_tel) > 0){result = true;}else{result = false;}return result;
}
void write_person(FILE* fp, Person* person)
{// 就像read_person 是从文件里读取内容，使用的是fscanf// 写入文件使用fprintf ，语法类比printf//(1) your code}
typedef struct _PersonManager
{Person m_allPerson[100];int size;
} PersonManager;
void InitPersonMgr(PersonManager* personMgr)
{//(2) your code}
void push_back(PersonManager* personMgr, Person* person)
{personMgr->m_allPerson[personMgr->size++] = *person;
}
void erase_person(PersonManager* personMgr, int index)
{assert(index >= 0 && index < personMgr->size);for (int i = index; i < personMgr->size - 1; i++){//(3) your code}personMgr->size -= 1;
}
void InputOnePerson(PersonManager* personMgr);
bool DeletePerson(PersonManager* personMgr)
{printf("Please input person id for delete:");int id;scanf("%d", &id);for (int i = 0; i < personMgr->size; i++){if (personMgr->m_allPerson[i].m_id == id){//(4) your codereturn true;}}return false;
}
bool QueryPersonByName(PersonManager* personMgr)
{printf("Please input name for query:");char name[NAME_LENGTH];scanf("%s", name);for (int i = 0; i < personMgr->size; i++){if (strcmp( personMgr->m_allPerson[i].m_name, name) == 0){printf("Find:\n");//(5) your code return true;}}printf("not found %s\n", name);return false;
}
bool QueryPersonByTel(PersonManager* personMgr)
{printf("Please input tel for query:");char tel[TEL_LENGTH];scanf("%s", tel);for (int i = 0; i < personMgr->size; i++){if (strcmp(personMgr->m_allPerson[i].m_tel, tel) == 0){printf("Find:\n");print_person(&personMgr->m_allPerson[i]);return true;}}printf("not found %s\n", tel);return false;
}
void ShowAllPerson(PersonManager* personMgr)
{printf("All Person:\n");printf("id   name           tel\n");for (int i = 0; i < personMgr->size; i++){print_person(&personMgr->m_allPerson[i]);}
}
bool SaveAllPersonToFile(PersonManager* personMgr)
{FILE* fp = fopen("data_saved.txt", "w");//以写方式打开文件if (fp == NULL){printf("can not open file data_saved.txt for write data.\n");return false;}for (int i = 0; i < personMgr->size; i++){//(6) your code}fclose(fp);return true;
}
bool LoadAllPersonFromFile(PersonManager* personMgr, const char* fileName)
{FILE* fp = fopen(fileName, "r");//只读方式打开文本文件if (fp == NULL){printf("load data failed . file %s not exits.\n", fileName);return false;}Person person;while (read_person(fp, &person)){push_back(personMgr, &person);}printf("load data from file success.\n");fclose(fp);return true;
}
void InputOnePerson(PersonManager* personMgr)
{printf("Please input one person：\n");printf("Please input id：");int id;scanf("%d", &id);Person person;memset(&person, 0, sizeof(Person));person.m_id = id;for (int i = 0; i < personMgr->size; i++){if (personMgr->m_allPerson[i].m_id == id){printf("%d already existed! Save failed.\n", id);return;}}printf("Please input name：");scanf("%s", person.m_name);printf("Please input tel：");scanf("%s", person.m_tel);printf("Input finished, save successed.\n");//(7) your code}
int main(int argv, char* argc[])
{PersonManager personMgr;InitPersonMgr(&personMgr);LoadAllPersonFromFile(&personMgr, "input_data.txt");ShowAllPerson(&personMgr);while(true){printf("input a commond : \n");printf("1 [AddPerson]\n");printf("2 [ShowAllPerson]\n");printf("3 [QueryPerson by name]\n");printf("4 [QueryPerson by tel]\n");printf("5 [SaveAllPersonToFile]\n");printf("6 [DeletePerson]\n");printf("0 [ExitAndSaveChange]\n");int commond;scanf("%d", &commond);switch(commond){case 1: { InputOnePerson(&personMgr); break;}case 2: { ShowAllPerson(&personMgr); break;}case 3: { QueryPersonByName(&personMgr); break;}case 4: { QueryPersonByTel(&personMgr); break;}case 5: { SaveAllPersonToFile(&personMgr); break;}case 6: { DeletePerson(&personMgr); break;}case 0: { SaveAllPersonToFile(&personMgr); return 0;}default:{ printf("System Exit.\n"); return 0;}}}return 0;
}

运行结果

和C++ 一模一样：

load data from file success.
All Person:
id   name           tel
2    zhangsan2      13788889992
3    zhangsan3      13788889993
4    zhangsan4      13788889994
5    wanger         13333333333
input a commond :
1 [AddPerson]
2 [ShowAllPerson]
3 [QueryPerson by name]
4 [QueryPerson by tel]
5 [SaveAllPersonToFile]
6 [DeletePerson]
0 [ExitAndSaveChange]
2
All Person:
id   name           tel
2    zhangsan2      13788889992
3    zhangsan3      13788889993
4    zhangsan4      13788889994
5    wanger         13333333333
input a commond :
1 [AddPerson]
2 [ShowAllPerson]
3 [QueryPerson by name]
4 [QueryPerson by tel]
5 [SaveAllPersonToFile]
6 [DeletePerson]
0 [ExitAndSaveChange]
1
Please input one person：
Please input id：1
Please input name：zhangsan
Please input tel：13344445555
Input finished, save successed.
input a commond :
1 [AddPerson]
2 [ShowAllPerson]
3 [QueryPerson by name]
4 [QueryPerson by tel]
5 [SaveAllPersonToFile]
6 [DeletePerson]
0 [ExitAndSaveChange]
2
All Person:
id   name           tel
2    zhangsan2      13788889992
3    zhangsan3      13788889993
4    zhangsan4      13788889994
5    wanger         13333333333
1    zhangsan       13344445555
input a commond :
1 [AddPerson]
2 [ShowAllPerson]
3 [QueryPerson by name]
4 [QueryPerson by tel]
5 [SaveAllPersonToFile]
6 [DeletePerson]
0 [ExitAndSaveChange]
3
Please input name for query:zhangsan
Find:
1    zhangsan       13344445555
input a commond :
1 [AddPerson]
2 [ShowAllPerson]
3 [QueryPerson by name]
4 [QueryPerson by tel]
5 [SaveAllPersonToFile]
6 [DeletePerson]
0 [ExitAndSaveChange]
3
Please input name for query:zhang
not found zhang
input a commond :
1 [AddPerson]
2 [ShowAllPerson]
3 [QueryPerson by name]
4 [QueryPerson by tel]
5 [SaveAllPersonToFile]
6 [DeletePerson]
0 [ExitAndSaveChange]
4
Please input tel for query:13344445555
Find:
1    zhangsan       13344445555
input a commond :
1 [AddPerson]
2 [ShowAllPerson]
3 [QueryPerson by name]
4 [QueryPerson by tel]
5 [SaveAllPersonToFile]
6 [DeletePerson]
0 [ExitAndSaveChange]
4
Please input tel for query:1334444
not found 1334444
input a commond :
1 [AddPerson]
2 [ShowAllPerson]
3 [QueryPerson by name]
4 [QueryPerson by tel]
5 [SaveAllPersonToFile]
6 [DeletePerson]
0 [ExitAndSaveChange]
6
Please input person id for delete:4
input a commond :
1 [AddPerson]
2 [ShowAllPerson]
3 [QueryPerson by name]
4 [QueryPerson by tel]
5 [SaveAllPersonToFile]
6 [DeletePerson]
0 [ExitAndSaveChange]
2
All Person:
id   name           tel
2    zhangsan2      13788889992
3    zhangsan3      13788889993
5    wanger         13333333333
1    zhangsan       13344445555
input a commond :
1 [AddPerson]
2 [ShowAllPerson]
3 [QueryPerson by name]
4 [QueryPerson by tel]
5 [SaveAllPersonToFile]
6 [DeletePerson]
0 [ExitAndSaveChange]
5
input a commond :
1 [AddPerson]
2 [ShowAllPerson]
3 [QueryPerson by name]
4 [QueryPerson by tel]
5 [SaveAllPersonToFile]
6 [DeletePerson]
0 [ExitAndSaveChange]
0

最终保存数据到文件 data_saved.txt

文件 data_saved.txt 的内容为：

2 zhangsan2 13788889992
3 zhangsan3 13788889993
5 wanger 13333333333
1 zhangsan 13344445555

你的结果也是这样吗？

答案在此

C++自学精简教程 全部答案

学生代码的运行结果