从txt文件读入vector,然后用数字C ++排序

时间:2014-11-22 21:00:34

标签: c++ file vector

03 Ribena 7 2.20

17咖啡76 1.50

24茶21 1.10

39 Sprite 3 1.70

56 pla 18 1.70

68 Orange 106 2.20

77 Lime 11 2.10

86葡萄34 2.30

55巧克力15 2.70

16 Frosty 20 2.20

65 Lemonade 21 1.90

55 Yoghurt 99 3.40

05 Punch 3 1.70

这些记录需要根据第一列上的ITEM NUMBER进行排序。

void record_initialize()
{
    vector<string> record;
    cout << "\n";
    record.push_back("03""\t\t""Ribena""\t\t""7""\t\t""2.20");
    record.push_back("17"  "\t\t""Coffee"  "\t\t""76"  "\t\t""1.50");
    record.push_back("24"  "\t\t""Tea"     "\t\t""21"   "\t\t""1.10");
    record.push_back("39"  "\t\t""Sprite"   "\t\t""3" "\t\t""1.70");
    record.push_back("56"   "\t\t""Cola"  "\t\t""18" "\t\t""1.70");
    record.push_back("68"  "\t\t""Orange"  "\t\t""106""\t\t""2.20");
    record.push_back("77"  "\t\t""Lime"    "\t\t""11" "\t\t""2.10");
    record.push_back("86"  "\t\t""Grape"     "\t\t""34" "\t\t""2.30");
    record.push_back("55" "\t\t" "Chocolate"   "\t""15" "\t\t""2.70");
    record.push_back("16"  "\t\t""Frosty"    "\t\t""20" "\t\t""2.20");
    record.push_back("55" "\t\t" "Lemonade"  "\t""21" "\t\t""1.90");
    record.push_back("55"  "\t\t""Yoghurt"   "\t\t""99" "\t\t""3.40");
    record.push_back("05"  "\t\t""Punch"     "\t\t""3"  "\t\t""1.70");
    cout << "\n";
    //sort(record.begin(), record.end());
    ofstream output_file("Drinks.txt");
    ostream_iterator<string> output_iterator(output_file, "\n");
    copy(record.begin(), record.end(), output_iterator);
}
void record_add()
{
    DrinkRecord d;
    cout << "\n";
    cout << "Please enter the item no.: ";
    cin >> d.no;
    cout << "\n";
    cout << "Please enter name of drink: ";
    cin >> d.name;
    cout << "\n";
    cout << "Please enter the quantity: ";
    cin >> d.quantity;
    cout << "\n";
    cout << "Please enter the unit price: ";
    cin >> d.price;
    cout << "\n";
    ofstream myfile;
    myfile.open("Drinks.txt", ios::app | ios::out);
    cout << "\n";
    myfile << d.no << "\t\t" << d.name << "\t\t" << d.quantity << "\t\t" << d.price << endl;
    myfile.close();
}

void record_view()
{

    cout << "\n";
    cout << "ItemNo" << "\t\t" << "ItemName" << "\t" << "Quantity" << "\t" << "Unit Price" << endl;
    cout << "\n";
    string getcontent;
    ifstream openfile("Drinks.txt");
    if (openfile.is_open())
    {
        while (!openfile.eof())
        {
            getline(openfile, getcontent);
            cout << getcontent << endl;
        }
    }
}

我已成功完成这一部分。但是,在向饮料库存添加新商品后,我现在遇到问题。我的讲师告诉我将txt文件读入矢量,然后对矢量进行排序,然后显示结果。我似乎无法采取正确的步骤。任何帮助将非常感激。 我试过这样的事情。

void read_File() //Read the file into the vector function definition
{

    vector<string> logs;
    string line;


    cout << "Testing loading of file." << endl;
    ifstream myfile("Drinks.txt");
    if (myfile.is_open())
    {
        while (!myfile.eof())
        {
            getline(myfile, line);
            logs.push_back(line);
            sort(line.begin(), line.end());

        }
        myfile.close();
    }
    else{
        cout << "Unable to open file." << endl;
    }

}

2 个答案:

答案 0 :(得分:0)

在阅读每一行后,您似乎正在排序。请注意,对sort的调用是在循环内部。这意味着在每次迭代时(在您阅读的每一行之后),您都会调用sort。如果我正确理解了您的作业,则需要对文件中的所有行(logs)进行排序。如果是这样,那么这意味着您只需要拨打sort一次。而不是将该行作为参数传递,您可能需要将logs向量作为参数传递给它,因为您要对日志进行排序。

答案 1 :(得分:0)

阅读整个文件后,您必须对其进行一次排序。
另外,sort(line.begin(),line.end());将根据字符串比较规则对向量中的字符串进行排序,但是,您需要根据第一列进行排序。
你需要编写自己的自定义比较器,它从两个被比较的字符串读取第一列。

由于这看起来像一个类问题,我将让你编写下面的比较器函数。
请参阅以下链接以获取更多帮助。

sort(line.begin(), line.end(), mycolumncomparator);

// Fill the below function correctly
bool mycolumncomparator(const std::string& i, const std:string& j) 
{ 
    // Read the first column from both strings
    // covert them into int using atoi
    // return (int1 < int2);
}

请参阅此处:http://www.cplusplus.com/reference/algorithm/sort/