C++ 中的学生数据管理
现在，我们生活的方方面面都在使用数据库。数万亿字节的数据存储在世界各地的服务器中。 SQL 是使用此类数据库的最基本方法之一。但是你有没有想过用C++来维护这样一个数据库。在这篇文章中，我们将讨论根据用户类型在文本文件上实现不同的视图并进行相应的编辑。
使用此代码存储的数据是：
1) 注册号
2) 名称
3) CSE1001 成绩
4) CSE1002 成绩
5) 监考人 ID
以下代码是用 C++ 编写的学生管理项目的简单实现
C++
// Include all the necessary libraries.
#include
#include
#include
#include
using namespace std;
int main()
{
// Considering the max length of data entered (name) to
// be 15.
char data[15];
int n = 0, option = 0, count_n = 0;
// This is the initial mark alloted to a subject.
string empty = "00";
string proctor = "";
// Name of the file in which DB is stored.
ifstream f("Example.txt");
string line;
// The following for loop counts the total number of
// lines in the file.
for (int i = 0; std::getline(f, line); ++i) {
count_n++;
}
while (option != 6) {
// This prints out all the available options in the
// DB
cout << "\nAvailable operations: \n1. Add New "
"Students\n2."
<< "Student Login\n3. Faculty Login\n4. "
"Proctor Login\n5. Admin View\n"
<< "6. Exit\nEnter option: ";
cin >> option;
if (option == 1) {
cout << "Enter the number of students: ";
cin >> n;
count_n = count_n + n;
for (int i = 0; i < n; i++) {
ofstream outfile;
outfile.open("Example.txt", ios::app);
// The entire data of a single student is
// stored line-by-line.
cout << "Enter your registration number: ";
cin >> data;
outfile << data << "\t";
cout << "Enter your name: ";
cin >> data;
int len = strlen(data);
while (len < 15) {
data[len] = ' ';
len = len + 1;
}
outfile << data << "\t";
// Inserting empty data initially into the
// file
outfile << empty << "\t";
outfile << empty << "\t";
cout << "Enter your proctor ID: ";
cin >> proctor;
outfile << proctor << endl;
}
}
else if (option == 2) {
char regno[9];
cout << "Enter your registration number: ";
cin >> regno;
ifstream infile;
int check = 0;
infile.open("Example.txt", ios::in);
// This loop prints out the data according to
// the registration number specified.
while (infile >> data) {
if (strcmp(data, regno) == 0) {
cout
<< "\nRegistration Number: " << data
<< endl;
infile >> data;
cout << "Name: " << data << endl;
infile >> data;
cout << "CSE1001 mark: " << data
<< endl;
infile >> data;
cout << "CSE1002 mark: " << data
<< endl;
infile >> data;
cout << "Proctor ID: " << data << endl;
infile.close();
check = 1;
}
}
if (check == 0) {
cout << "No such registration number found!"
<< endl;
}
}
// This loop is used to view and add marks to the
// database of a student.
else if (option == 3) {
char subcode[7];
cout << "Enter your subject code: ";
cin >> subcode;
string code1 = "CSE1001", code2 = "CSE1002",
mark = "";
ifstream infile;
int check = 0;
cout << "\nAvailable operations: \n1. Add data "
"about marks\n"
<< "2. View data\nEnter option: ";
cin >> option;
if (option == 1) {
cout
<< "Warning! You would need to add mark"
<< "details for all the students!"
<< endl;
for (int i = 0; i < count_n; i++) {
fstream file("Example.txt");
// The seek in file has been done
// according to the length
// of the data being inserted. It needs
// to adjusted accordingly for different
// lengths of data.
if (strcmp(subcode, code1.c_str())
== 0) {
file.seekp(26 + 37 * i,
std::ios_base::beg);
cout << "Enter the mark of student#"
<< (i + 1) << " : ";
cin >> mark;
file.write(mark.c_str(), 2);
}
if (strcmp(subcode, code2.c_str())
== 0) {
file.seekp(29 + 37 * i,
std::ios_base::beg);
cout << "Enter the mark of student#"
<< (i + 1) << " : ";
cin >> mark;
file.write(mark.c_str(), 2);
}
}
}
// This loop is used to view marks of a student.
// The extra infile commands have been used to
// get a specific mark only since the data has
// been separated by a tabspace.
else if (option == 2) {
infile.open("Example.txt", ios::in);
if (strcmp(subcode, code1.c_str()) == 0) {
cout << "Registration number - Marks\n"
<< endl;
while (infile >> data) {
cout << data;
infile >> data;
infile >> data;
cout << " - " << data << endl;
infile >> data;
infile >> data;
check = 1;
}
}
infile.close();
infile.open("Example.txt", ios::in);
if (strcmp(subcode, code2.c_str()) == 0) {
cout << "Registration number - Marks\n"
<< endl;
while (infile >> data) {
cout << data;
infile >> data;
infile >> data;
infile >> data;
cout << " - " << data << endl;
infile >> data;
check = 1;
}
}
}
infile.close();
if (check == 0) {
cout << "No such subject code found!"
<< endl;
}
}
// This loop displays all the details of students
// under the same proctor ID.
else if (option == 4) {
char procid[7];
cout << "Enter your proctor ID: ";
cin >> procid;
int check = 0;
char temp1[100], temp2[100], temp3[100];
char temp4[100], id[100];
ifstream infile;
infile.open("Example.txt", ios::in);
while (infile >> temp1) {
infile >> temp2;
infile >> temp3;
infile >> temp4;
infile >> id;
if (strcmp(id, procid) == 0) {
cout << "\nRegistration Number: "
<< temp1 << endl;
cout << "Name: " << temp2 << endl;
cout << "CSE1001 Mark: " << temp3
<< endl;
cout << "CSE1002 Mark: " << temp4
<< endl;
check = 1;
}
}
if (check == 0) {
cout << "No such proctor ID found!" << endl;
}
}
// This loop acts as an admin view to see all the
// data in the file.
else if (option == 5) {
char password[25];
cout << "Enter the admin password: ";
cin >> password;
// This variable value can be changed according
// to your requirement of the administrator
// password.
string admin_pass = "admin";
if (strcmp(password, admin_pass.c_str()) == 0) {
cout << "Reg No. "
"\tName\tCSE1001\tCSE1002\tProctor "
"ID"
<< endl;
ifstream infile;
infile.open("Example.txt", ios::in);
char data[20];
while (infile >> data) {
cout << data << "\t";
infile >> data;
cout << data << "\t";
infile >> data;
cout << data << "\t";
infile >> data;
cout << data << "\t";
infile >> data;
cout << data << endl;
}
}
}
}
} 输出：
Available operations:
1. Add New Students
2. Student Login
3. Faculty Login
4. Proctor Login
5. Admin View
6. Exit
Enter option: 1
Enter the number of students: 2
Enter your registration number: 15BCE2083
Enter your name: Dheeraj
Enter your proctor ID: 1001
Enter your registration number: 15BCE2082
Enter your name: Rohan
Enter your proctor ID: 1002
Available operations:
1. Add New Students
2. Student Login
3. Faculty Login
4. Proctor Login
5. Admin View
6. Exit
Enter option: 3
Enter your subject code: CSE1001
Available operations:
1. Add data about marks
2. View data
Enter option: 1
Warning! You would need to add mark details for all the students!
Enter the mark of student#1 : 52
Enter the mark of student#2 : 89
No such subject code found!
Available operations:
1. Add New Students
2. Student Login
3. Faculty Login
4. Proctor Login
5. Admin View
6. Exit
Enter option: 5
Enter the admin password: admin
Reg No. Name CSE1001 CSE1002 Proctor ID
15BCE2083 Dheeraj 52 00 1001
15BCE2082 Rohan 89 00 1002
Available operations:
1. Add New Students
2. Student Login
3. Faculty Login
4. Proctor Login
5. Admin View
6. Exit
Enter option: 6
------------------
(program exited with code: 0)
Press return to continue