Advanced templates

https://github.com/wuye9036/CppTemplateTutorial
chap1  无他， 唯手熟尔

Reading notes: till 2.3 即用即推导 (2018.05.29)

Implement Case Insensitive string by overwriting C++ basic_string template traits parameter

include<string>
#include<iostream>
using namespace std;
class CaseInsensitiveTraits: public std::char_traits<char> {
public:
    static bool lt (char one, char two) {
        return std::tolower(one) < std::tolower(two);
    }

    static bool eq (char one, char two) {
        return std::tolower(one) == std::tolower(two);
    }

    static int compare (const char* one, const char* two, size_t length) {
        for (size_t i = 0; i < length; ++i) {
            if (lt(one[i], two[i])) return -1;
            if (lt(two[i], one[i])) return +1;
        }
        return 0;
    }
};

typedef basic_string<char, CaseInsensitiveTraits> cistring;

int main(void) {
    cistring c1 = "HI!", c2 = "hi!";
    if (c1 == c2) {  // Always true
        cout << "Strings are equal." << endl;
    }

    cout << "c1 length is " << c1.size() << endl;
    cout << "Find 'I' in c1 length: " << c1.find('I') << endl;
    cout << "Find 'h' in c1 length: " << (int) c1.find('h') << endl;
}