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 15
typedef 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 code
return 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
