我试着打开一个文件，一次显示20行，直到文件结束，然后关闭程序。真实的简单。
代码如下：

int main()
{
    using namespace std;

    //try catch block sets up exception handling for files that do not exist. I added a few different
    //text files to search for
    try {
        //intro message and prompt for file name
        cout << "Welcome to the Advanced File I/O program." << endl;
        cout << "Please enter the name of the text file you would like to search for: ";
        string input;
        cin >> input;
        //concatonate input with .txt file designation
        string fileName = input + ".txt";
        fstream myFile;
        //open the file and read it in
        myFile.open(fileName, ios::in);
        //if the file exists
        if (myFile.is_open()) {
            string line;
            //while there are lines to be read in
            while (getline(myFile, line)) {
                
                //display 20 at a time
                for (int i = 0; i < 20 && getline(myFile, line); i++) {
                    cout << line << endl;
                }
                //app console controle
                system("pause");
                system("cls");
            }
            //app console controle
            system("pause");
            system("cls");
            //close the file once it's all read in and display end message
            myFile.close();
            system("cls");
            cout << "You have reached the end of the text file. " << endl;
            cout << "Thank you for visiting! Goodbye!" << endl;
            system("pause");
            exit(0);

        }
        //if the file does not open (does not exist) throw the error exception and close the program
        else if (myFile.fail()) {
            throw exception("File does not exist. Closing Program.");
            cout << endl;
            system("cls");
            exit(0);
        }
    }
    //catch the exception and display the message
    catch (exception& e) {
        cout << "\nError caught!" << endl;
        cout << e.what();
    }
}

问题是每次在for循环中，它都会跳过输出的第一行。我很确定这是发生的，因为我调用了getline()两次。但是，我不知道如何解决这个问题。
对于那些要告诉我不要使用using namespace std;的人，我是这个作业所在课程的要求。