Question

我只是检查设置比较器的有效STL（书籍）示例以实现不区分大小写的设置，但我遇到了问题（visual studio说comaparator无效，但它在ideone中工作）。我确信在我的实施中存在一些问题，即使这样也不会让人感到困惑。

以下是代码

#include <iostream>
#include <set>
#include <map>
#include <algorithm>

using namespace std;
    inline int ciCharCompare(char c1, char c2) // case-insensitively compare chars
    { // c1 and c2, returning -1 if c1 < c2,
      //0 if c1==c2, and 1 if c1 > c2
        int Ic1 = tolower(static_cast<unsigned char>(c1)); //see below for
        int Ic2 = tolower(static_cast<unsigned char>(c2)); // info on these
        if (Ic1 < Ic2) return -1;
        if (Ic1 > Ic2) return 1;
        return 0;
    }

struct CiStringCompare : public std::binary_function<string, string, bool>
{

    int ciStringCompareImpl(const string& s1, const string& s2) const
    {
        auto p = mismatch( //see below for an
            s1.begin(), s1.end(), //explanation of why
            s2.begin(), //we need not2;see
            not2(ptr_fun(ciCharCompare))); //Item 41 for why we
                                           // need ptr_fun
        if (p.first == s1.end()) { //if true, either s1 and
            if (p.second == s2.end()) return 0; // s2 are equal or
            else return -1; //s1 is shorter than s2
        }
        return ciCharCompare(*p.first, *p.second);
    }
    int xxxx(const string& s1, const string& s2) const
    {
        if (s1.size() <= s2.size()) return ciStringCompareImpl(s1, s2);
        else return -ciStringCompareImpl(s2, s1);
    }

    int operator()(const string& str1, const string& str2) const {
        return xxxx(str1, str2);
    }
};

class DifferenceBetweenEquivalenceandEquality
{
    // Comparator functor 


    set<string, CiStringCompare> s;
public:
    DifferenceBetweenEquivalenceandEquality(const vector<string>& v)
    {
        for (const auto& x : v)
            s.insert(x);
    }

    void print() {
        for(const auto& x: s)
            cout << x << endl;
    }
};

int main()
{
    DifferenceBetweenEquivalenceandEquality dbee({ "STL","stl","aaa","bbb" });
    dbee.print();
    return 0;
}

虽然它在ideone中工作得很好，所以我对于什么使比较器有效以及每个这些的等式，等价和排序效果感到困惑。例如::在正常情况下我得到

STL stl aaa bbb

但是使用下面的比较器我得到

aaa bbb stl STL

inline string toLowerCase(const string& str) {
    string res(str);
    int i;

    for (i = 0; i < (int)res.size(); i++)
        res[i] = (char)tolower(res[i]);

    return res;
}

class NormalComparator
{
public:
    bool operator()(const string& s1, const string& s2)
    {
        return toLowerCase(s1) < toLowerCase(s2) ||
            !(toLowerCase(s2) < toLowerCase(s1)) && s1 < s2;
    }
};

比较器不区分大小写的字符串集

0 个答案: