Certainly, let's go through the code step by step and explain its functionality:
1. Include necessary header files:
```cpp
#include <iostream>
#include <fstream>
#include <string>
```
These lines include the required C++ standard library headers for input/output, file handling, and working with strings.
2. Define a `Student` struct:
```cpp
struct Student {
int id;
std::string name;
};
```
This struct defines the structure of a student, containing two fields: `id` (an integer representing the student's ID) and `name` (a string representing the student's name).
3. Function `writeStudentData`:
```cpp
void writeStudentData(const std::string& filename, const Student& student) {
// Open the file in append mode
std::ofstream outFile(filename, std::ios::app);
if (outFile.is_open()) {
outFile << student.id << " " << student.name << "\n";
outFile.close();
std::cout << "Student information has been written to the file." << std::endl;
} else {
std::cerr << "Error: Unable to open the file for writing." << std::endl;
}
}
```
- This function takes two parameters: a filename and a `Student` object.
- It opens the file specified by the filename in append mode (`std::ios::app`) and writes the student's ID and name to the file, separated by a space.
- It then closes the file and prints a message to indicate whether the operation was successful.
4. Function `readStudentData`:
```cpp
void readStudentData(const std::string& filename) {
// Open the file for reading
std::ifstream inFile(filename);
if (inFile.is_open()) {
Student student;
while (inFile >> student.id) {
inFile.get(); // Consume the space character
std::getline(inFile, student.name);
std::cout << "Student ID: " << student.id << ", Student Name: " << student.name << std::endl;
}
inFile.close();
} else {
std::cerr << "Error: Unable to open the file for reading." << std::endl;
}
}
```
- This function takes a filename as a parameter and opens the file for reading using `std::ifstream`.
- It reads student information from the file line by line. It extracts the ID as an integer and consumes the space character before reading the student's name as a string.
- The student information is then displayed, and the file is closed.
5. The `main` function:
- It defines a constant string `filename` as the name of the file where student data is stored.
- Inside a while loop, it presents a menu to the user, allowing them to:
- Add a student (enter ID and name).
- Display all students' information.
- Quit the program.
- For adding a student, the program reads the student's ID and name, and for displaying all students, it reads and prints all student information from the file.
- The program keeps running until the user chooses to quit by entering '3'.
- It uses `std::cin` and `std::cout` for input and output and correctly handles student names with spaces using `getline` and consuming the newline characters.
- Error messages are displayed if there are issues with file operations.
In summary, this C++ program provides a simple file-based system for storing and retrieving student information, including student IDs and names, using functions and a menu-driven interface.