如何编辑文本文件中的特定行？

Question

我应该如何编辑文本文件中的特定行？以及我应该如何避免覆盖问题。 （如何保留之前添加的记录，而不是用新记录替换它们？）

我尝试使用 line.replace 但它显示“没有匹配的成员函数用于调用替换”。

else if(choice == 4){

//            count++;

    string edit;
    string newdate;
    double newincome;
    double newoutcome;
    double EditTodayBalance = 0;
    string emptySpace = "         ";
//            string sentence;

    cout << " There are " << count << " record(s) in the file " <<     endl;
    cout << " Please enter the date to edit " << endl;
    cin >> edit;



    size_t pos;
    ifstream Record("BankRecord.txt");
    if (Record.is_open()) {
        while (getline(Record, line)) {
            pos = line.find(edit);
            if (pos != string::npos) // string::npos is returned if 
string is not found
                {
                    cout << line << endl;

                    cout << " Enter what you want to replace " << endl;

                    cout << " Please enter the new date you want to put " << endl;
                    cin >> newdate;
                    cout << " Please enter the new income you want to put " << endl;
                    cin >> newincome;
                    cout << " Please enter the new outcome you want to put " << endl;
                    cin >> newoutcome;

                    cout << "            Your new Record is                 " << endl;
                    cout << count << emptySpace << newdate << emptySpace << newincome << emptySpace << newoutcome << endl;


                    //line.replace()
            }
        }
    }
    EditTodayBalance = newincome - newoutcome;
    cout << " Today's balance is " << EditTodayBalance << endl;

    cout << " Please reenter your choice " << endl;
    cin >> choice;
}

我希望旧行是“ 1 2/2/2019 32 21 ”并且我输入新行是“ 1 2/3/2019 22 11 ”。然后当我打开文件时，记录将是新的。

Answer 1

恐怕您将不得不重新编写整个文件。逐行读取文件的内容，将其存储在内存中（可能是字符串向量）。现在在该向量中的指定行上进行编辑。操作完成后，将vector的全部内容转储到另一个文件中。您可以稍后替换原始文件。