我应该使用什么数据结构来建模数据库/表？ [英] What data structure should I use to model a database/table?

问题描述

┃Name|Age|..┃
┠────┼───┼──┨
┃John│025│..┃
┃Carl│033│..┃
┃....│...│..┃

在这种情况下，我的意思是一个具有固定列大小和可变大小的未排序行的表，可以对其进行处理

In this case I mean a table with a fixed column size and a variable size of unsorted rows which can be addressed by an id.

在C ++ 11（或更早版本）中是否存在可以表示这种数据的数据结构？

Is there a data structure in C++11 (or earlier) that can represent data like this?

我想到了几种欺骗这种结构的方法，但都不是完美的。

I thought of a couple of ways of cheating such a structure, but none of them is perfect.

std::vector<std::string> name;
std::vector<unsigned int> age;

// Write
name.push_back("John");
age.push_back(25);

// Read
std::cout << "The first entry is (" << name[0] << " | " << age[0] << ")\n";

定义一个包含许多列的表需要很多标记，并通过调用<每个 std :: vector 上的code> push_back 确实很乏味。

Defining a table with many columns takes a lot of markup, though, and writing to it by calling push_back on each std::vector is really tedeous.

（在这种情况下，<< c $ c> std :: pair 就足够了）

(std::pair would be enough in this case)

std::vector<std::tuple<std::string, unsigned int>> table;

// Write
table.push_back(std::make_tuple("John", 25));

// Read 1
std::string name;
unsigned int age;
std::tie(name, age) = table[0];
std::cout << "The first entry is (" << name << " | " << age << ")\n";

// Read 2
enum
{
    NAME = 0,
    AGE
}
std::cout << "The first entry is (" << std::get<NAME>(table[0]) << " | "
<< std::get<AGE>(table[0]) << ")\n";

（对不起，如果我在这里弄乱了东西，我已经知道存在 std :: tuple 从昨天开始）

(Sorry, if I messed something up here; I've known about the existence of std::tuple since yesterday)

这很好，但是需要花很多时间来阅读这次，当您必须定义要放入值的新变量时，只需对所需的任何变量执行 std :: tie 值，但变得不可读。第二种方法几乎是完美的，但是我不希望在C ++ 11中使用隐式枚举。

This is fine, but reading from it takes a lot of markup, this time, when you have to define new variables that you want to put the values in. You could just do the std::tie to whatever variable you need the values at, but that becomes unreadable. The second method is almost perfect, but using implicit enums is not something I want to do in C++11.

enum
{
    NAME = 0,
    AGE
}

std::vector<std::array<std::string, 2> table;

// Write
table.push_back({"John", "25"});

// Read
std::cout << "The first entry is (" << table[0][NAME] << " | " << table[0][AGE] << ")\n";

这也很不错，但是它遇到了与2.2相同的问题。而且，这仅允许 std :: string 值。作为交换，它提供了更短更好的语法。

This is also pretty good, but it suffers the same problem as 2.2 did. Also this only allows std::string values. In exchange it offers shorter and nicer syntax, though.

推荐答案

我建议使用 std :: vector<记录> 来保存您的记录。

I suggest a std::vector<Record> to hold your records.

使用 std :: map< key，vector_index> 作为记录中的索引。这样一来，您就可以通过不同的搜索条件访问记录，而无需始终对向量进行排序。

Use std::map<key, vector_index> as an index into your records. This will enable you to access records by different search criteria without sorting the vector all the time.

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