C ++：C字符串集 [英] C++: set of C-strings

问题描述

我想创建一个，以便我可以检查某个字是否在集合中使用set :: find

I want to create one so that I could check whether a certain word is in the set using set::find

但是，C字符串是指针，所以默认情况下，集合将通过指针值进行比较。为了正确地运行，它必须取消引用它们并比较字符串。

However, C-strings are pointers, so the set would compare them by the pointer values by default. To function correctly, it would have to dereference them and compare the strings.

我可以传递构造函数作为比较器的strcmp（）函数的指针，不是我想要它的工作。我可能想检查的词可能是较长字符串的一部分，并且我不想创建一个新的字符串，由于性能问题。如果没有为集合，我会使用strncmp（a1，a2，3）来检查前3个字母。事实上，3可能是最长的时间，所以我很好与第三个参数常数。

I could just pass the constructor a pointer to the strcmp() function as a comparator, but this is not exactly how I want it to work. The word I might want to check could be part of a longer string, and I don't want to create a new string due to performance concerns. If there weren't for the set, I would use strncmp(a1, a2, 3) to check the first 3 letters. In fact, 3 is probably the longest it could go, so I'm fine with having the third argument constant.

有一种方法来构造一个集，将比较它的元素通过调用strncmp（）？非常感谢代码示例。

Is there a way to construct a set that would compare its elements by calling strncmp()? Code samples would be greatly appreciated.

这里是我想要做的伪代码：

Here's pseudocode for what I want to do:

bool WordInSet (string, set, length)
{
   for (each word in set)
    {
       if strncmp(string, word, length) == 0
            return true;
    }
    return false;
}

但我更喜欢使用标准库函数来实现它。 p>

But I'd prefer to implement it using the standard library functions.

推荐答案

创建包装函数：

bool myCompare(const char * lhs, const char * rhs)
{
    return strncmp(lhs, rhs, 3) < 0;
}

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