custom strcmp

my_strcmp.cpp

#include <cstdio>
#include <cstring>
#include <cassert>

typedef enum {
	MyOrderedAscending = -1,
	MyOrderSame,
	MyOrderedDescending
} MyComparisonResult;

MyComparisonResult my_strcmp_enum(const char * str1, const char * str2) {
	int val = strcmp(str1, str2);
	if(val < 0) {
		return MyOrderedAscending;
	} else if(val > 0) {
		return MyOrderedDescending;
	} else {
		return MyOrderSame;
	}
}

bool operator==(MyComparisonResult a, int b) {
	return ((int)a == b);
}

bool operator==(MyComparisonResult a, bool b) {
	return !((bool)a == b);
}

bool operator!=(MyComparisonResult a, int b) { return !(a == b); }
bool operator!=(MyComparisonResult a, bool b) { return !(a == b); }

// compile error
// error: conversion function must be a non-static member function
// operator bool(MyComparisonResult a) { return true; }


class ComparisonResult {
public:
	enum {
		ASC = -1,
		EQUAL,
		DESC
	};

	ComparisonResult(int val) : val(val) {}

	bool operator==(int x) {
		return ((int)val == x);
	}

	bool operator==(bool x) {
		return !((bool)val == x);
	}

	bool operator!=(int x) { return !(*this == x); }
	bool operator!=(bool x) { return !(*this == x); }

	operator bool() {
		return (val == EQUAL);
	}

	static ComparisonResult strcmp(const char *str1, const char *str2) {
		int raw = ::strcmp(str1, str2);
		if(raw < 0) {
			return ComparisonResult(ASC);
		} else if(raw > 0) {
			return ComparisonResult(DESC);
		} else {
			return ComparisonResult(EQUAL);
		}
	}
private:
	int val;
};

ComparisonResult my_strcmp(const char *str1, const char *str2)
{
	return ComparisonResult::strcmp(str1, str2);
}

void test_enum_version()
{
	assert(my_strcmp_enum("foo", "foo") == 0);
	assert(my_strcmp_enum("foo", "foo") == true);

	assert(my_strcmp_enum("foo", "bar") != 0);
	assert(my_strcmp_enum("foo", "bar") != true);

	// compatible with strcmp
	assert(my_strcmp_enum("1", "1") == strcmp("1", "1"));
	assert(my_strcmp_enum("1", "2") == strcmp("1", "2"));
	assert(my_strcmp_enum("2", "1") == strcmp("2", "1"));

	// if(my_strcmp...)
	printf("same : %d\n", my_strcmp_enum("foo", "foo"));
	printf("different : %d\n", !my_strcmp_enum("foo", "foo"));
}

void test_class_version()
{
	assert(my_strcmp("foo", "foo") == 0);
	assert(my_strcmp("foo", "foo") == true);
	assert(my_strcmp("foo", "foo"));

	assert(my_strcmp("foo", "bar") != 0);
	assert(my_strcmp("foo", "bar") != true);
	assert(!my_strcmp("foo", "bar"));

	// compatible with strcmp
	assert(my_strcmp("1", "1") == strcmp("1", "1"));
	assert(my_strcmp("1", "2") == strcmp("1", "2"));
	assert(my_strcmp("2", "1") == strcmp("2", "1"));
}

int main()
{
	test_enum_version();
	test_class_version();
	return 0;
}