Qfyilyi

I am working on a school project right now, and I need to build a Student Management System with QT. I have a txt file with student information listed in a line like:

Studentname accountpassword  studentid

Every time a user(student) input their studentname and password, I have to check if the name and password are in the database (which is the txt file right now).

This is what I am struggling with right now. I don't know how I can only search line by line. For example, if the first student user name is jack, and his password is 123456; At the same time, second student user name is peter, and his password is 23567.

How can I check if the username jack and 123456 are inputted at the same time?

void MainWindow::on_loginpush_clicked()

{

    QString username = ui -> lineedit_username -> text();

    QString password = ui -> lineedit_password -> text();



    if (username == "admin" && password =="admin")

    {

        Adminmanagment adminview;

        adminview.exec();

    }



    else if( (username != "admin") && (password !="admin"))

        {

            ifstream studentinfo("student.txt");

            if (!studentinfo.is_open())

            {



            }

            else 

            {

                string current_name;

                string current_password;

                string id;

                int numofcourses;

                int gpa;

                char newline;

                char space;

                bool valid =false;

                while((studentinfo>>current_name>>current_password>>id>>numofcourses>>gpa>>noskipws>>newline) &&newline == 'n')

                {   

                    if((current_name == username)&& (current_password== password))

                    {



                    }

                }

            }

}

My student.txt looks exactly like below

name password id number of courses gpa

jack 123456 900440123 4 0

testing 987654 900542015 4 2

testing2 8888 900145265 4 2

testing3 8888 900158256 4 0

Untested. Expects every line (including last line) ending with a newline character. Given you have 2 QStrings username and password:

#include <fstream>

#include <string>

#include <cctype>  // std::isspace()



// ...



std::istream& eat_whitespace(std::istream &is) // eats whitespace except 'n'

{

    int ch;

    while (is && (ch = is.peek()) != EOF && ch != 'n'

           && std::isspace(static_cast<char unsigned>(ch)))

    {

        is.get();

    }

    return is;

}



// ...



std::ifstream studentinfo{ "your_file" };

if (!studentinfo.is_open())

    // big trouble



std::string current_name;

std::string current_password;

std::string id;

int numofcourses;

int gpa;

char newline;

bool valid = false;



while ((studentinfo >> current_name >> current_password >> id >> numofcourses >> gpa

                    >> eat_whitespace >> std::noskipws >> newline >> std::skipws )

       && newline == 'n')

{

    if (current_name == username.toLocal8Bit().constData() &&

        current_password == password.toLocal8Bit().constData())

    {

        valid = true;

        break;

    }

}



// valid now true if credentials found.

You mentioned that you are using Qt. This question shows how to read a file line by line(Read a text file line by line in Qt) with Qfile.

You could then use QStrings in built equality operators to see if they’re the same. http://doc.qt.io/qt-5/qstring.html