SQL类似于C ++中的用法 [英] Sql Like similar use in c++

问题描述

我想问一个简单的问题，有什么方法可以在c ++中使用喜欢"这样的东西

I would like to ask a simple question, is there any way to use "like" such thing in c++

喜欢'％s，我想要用c ++这样的东西，因为如果我希望用户在程序中找到某些东西，那么它将简单地匹配所有相关数据.

LIKE '%s I want some thing like this in c++ because if I want user to find something in the program, this simply matches all the related data.

推荐答案

正则表达式可以用来实现您想要的.但是，有两个问题:

Regular expressions can be used to achieve what you want. There are two problems, though:

1.)与简单的SQL Like 关键字相比，它们使用起来确实复杂.

1.) They are really complicated to use compared to the simple SQL LIKE keyword.

2.)它们只是 C ++ 11 中的标准功能.如果使用旧" C ++编写，则必须使用 Boost.Regex 库.

2.) They are only a standard feature in C++11. If you write in "old" C++, then you'd have to use the Boost.Regex library.

但是...

在

Looking at the very basic LIKE examples at w3schools.com, you could in fact implement many of them in simple C++, using normal std::string functions.

例如，让我们看看这个:

For instance, let's have a look a this:

SELECT * FROM Customers WHERE City LIKE '%s'; 

这只是意味着对于每个字符串，您都要查看最后一个字符并检查它是否为's':

This just means that for every string, you look at the last character and check if it's 's':

std::string s;
// ...
if (!s.empty() && (s[s.size() - 1] == 's') {
    // ...
}

或者这个:

SELECT * FROM Customers WHERE Country NOT LIKE '%land%'; 

在C ++中:

std::string s;
// ...
if (s.find("land") == std::string::npos) {
    // ...
}

因此，最后，这实际上取决于您对 Like 到底想做什么.

So, in the end, it really depends on what exactly you'd want to do with LIKE.

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