c++学習点滴3

一、異常処理

0.     1
class MyException {  //      
public :
	MyException(){errorCode = -1;}
	MyException(int code) {errorCode = code;}
	int get(){return errorCode;}
private :
	int errorCode;
};
void fun () {
	try {
		throw MyException(1);
	} catch (MyException& e) { //         ，      
		cout << "exception: " << e.get() << endl;
	}
}
int main() {
	fun();

	return 0;
}
      2：
  
class MyException1 {};
class MyException2 {};

void fun () {
	try {
		int flag = 3; //     flag  ，       
		if (flag == 1) {
			throw MyException1();
		} else if (flag == 2) {
			throw MyException2();
		} else {
			throw string();
		}
	} catch (MyException1& e) {
		cout << "exception1 handled." << endl;
	} catch (MyException2& e) {
		cout << "exception2 handled." << endl;
	} catch (...) {  // catch-all
		cout << "other exception handled." << endl;
	}
	cout << "after exception handled." << endl;
}
int main() {
	fun();

	return 0;
}


1.       throw       
//          ，   throw        
void sample() throw(string); // JAVA   ：void sampe() throws StringException;
//void sample(){} // error.   throw  
//void sample() throw (int) {} // error. throw     
//void sample() throw (string, int){} // error. throw     
void sample() throw (string) {} // ok. throw      

2. c++    throw       (       int，      string，      MyException)

3. throw  1 --           throw    
  // throw                  
void sample() throw (string) { //      string  
	throw string("xxxx"); // OK.           
}

int main() {

	try {
		sample();
	} catch (string& str) {  //       
		cout << "exception: " << str << endl;
	}

	return 0;
}

4. throw  2 --           throw     

void sample() throw (string) { //      string  
	throw int(-1);  //        string   。
	               //   c++      unexpected()，        terminate()  
}

int main() {

	try {
		sample();  //    int     
	} catch (string& str) {
		cout << "exception: " << str << endl;
	} catch (...) { //    catch-all，        。  c++     unexpected()  
		cout << "catch all exceptioin" << endl;
	}

	cout << "after exception handler." << endl;

	return 0;
}

5. throw  3 --      throw  
//       throw      ，             throw  
void sample() throw (string) { }
void (*pf)() throw (string) = sample; // ok。  。
void (*pf2)() throw (string,int)  = sample; // ok.   
void (*pf3)() throw() = sample; // ok。
void (*pf4)()  = sample; // ok.
void (*pf5)() throw (int) = sample; // ok.

6.

二、汎用アルゴリズム

void printVec(vector<string>& svec);
bool comparestr(const string& str1, const string& str2);
//     
class LessThan {
public:
	//       ()   
	bool operator()(const string& str1, const string& str2) {
		return str1.size() < str2.size();
	}
};
class GreaterThan{
public:
	GreaterThan(){_size = 3;}
	GreaterThan(int size) {_size = size;}
	int size(){return _size;}
	bool operator() (const string &str) {return str.size()>_size;}
private :
	int _size;
};
class PrintElem {
public :
	void operator() (const string& elem) {
		cout << elem << " ";
	}
};
void fun () {
	string arr[] = {"aaa", "bbb", "ccc", "ddd"};
	vector<string> svec(arr, arr+4);
	printVec(svec);
	vector<string> svec2;
	svec2.push_back("xxx"); // xxx


	// copy
	copy(svec.begin(), svec.end(), back_inserter(svec2));
	printVec(svec2);  // xxx,aaa,bbb,ccc,ddd


	// sort
	sort(svec2.begin(), svec2.end());
	printVec(svec2); // aaa,bbb,ccc,ddd,xxx
	svec2.push_back("xxx");
	svec2.push_back("aaa");
	printVec(svec2); // aaa,bbb,ccc,ddd,xxx,xxx,aaa


	// unique           ，                
	vector<string>::iterator removedIter = unique(svec2.begin(), svec2.end(), comparestr);
	printVec(svec2); // aaa, bbb, ccc, ddd, xxx, aaa, aaa,
	svec2.erase(removedIter);
	printVec(svec2); // aaa, bbb, ccc, ddd, xxx, aaa,
	sort(svec2.begin(), svec2.end(), comparestr); //              
	printVec(svec2); // aaa, aaa, bbb, ccc, ddd, xxx,


	//     
	string arr2[] = {"abc", "ab", "a"};
	svec2 = vector<string>(arr2, arr2+3);
	stable_sort(svec2.begin(), svec2.end(), LessThan()); //            
	printVec(svec2); // a, ab, abc,


	//          
	string s1("abc");
	string s2("ab");
	LessThan lt;
	bool b = lt(s1, s2);  //   size
	cout << "lt(s1,s2): " << (b?"true":"flase") << endl; // false。   s1 size  s2 size


	// count_if
	string arr3[] = {"aaa", "bbbb", "ddddd", "cc"};
	svec2 = vector<string>(arr3, arr3+4);
	int cnt = count_if(svec2.begin(), svec2.end(), GreaterThan(3)); // size  3     
	cout << "cnt=" << cnt << endl; // 2
	cnt = count_if(svec2.begin(), svec2.end(), GreaterThan(2)); // size  2     
	cout << "cnt=" << cnt << endl; // 3


	// remove
	vector<string>::iterator iter = remove(svec2.begin(), svec2.end(), "bbbb");  //   bbbb
	printVec(svec2); // aaa, ddddd, cc, cc,
	svec2.erase(iter, svec2.end());
	printVec(svec2); // aaa, ddddd, cc,


	// for-each
	for_each(svec2.begin(), svec2.end(), PrintElem());
}




int main() {
	fun();
	return 0;
}


bool comparestr(const string& str1, const string& str2) {
	return str1.compare(str2) == 0;
}
void printVec(const vector<string>& svec) {
	vector<string>::const_iterator iter = svec.begin();
	for (; iter != svec.end(); iter++) {
		cout << *iter << ", ";
	}
	cout << endl;
}

 
 、    
 
 
class CompareInt{
public :
	bool operator() (const int& i1, const int& i2) {
		return i1 < i2;
	}
};

template<typename Type, class Comp>
const Type& min3(const Type *p, int size, Comp comp) {
	int minIndex = 0;
	for (int i = 0; i < size; i++) {
		if (comp(p[i], p[minIndex])) {
			minIndex = i;
		}
	}

	return p[minIndex];
}
  
 の  を います.
int arr[] = {4,3,1,2};
cout << "min number: " << min3(arr, 4, CompareInt()) << endl; // 1
  
 、     を る つの  
//     
template <typename T>
const T& min1(const T *p, int size) {
	int minIdx = 0;
	for (int i = 0; i < size; i++) {
		if (p[i] < p[minIdx]) {
			minIdx = i;
		}
	}

	return p[minIdx];
}

//     
bool intComp(const int& i1, const int& i2) {
	return i1 < i2;
}

template <typename T>
const T& min2(const T *p, int size, bool (*comp)(const T&, const T&) ){
	int minIdx = 0;
	for (int i = 0; i < size; i++) {
		if (comp(p[i], p[minIdx])) {
			minIdx = i;
		}
	}

	return p[minIdx];
}


//     
class Less{
public:
	bool operator()(const int &v1, const int &v2) {
		return v1 < v2;
	}
};
template <typename T>
const T& min3(const T *p, int size, Less less){
	int minIdx = 0;
	for (int i = 0; i < size; i++) {
		if (less(p[i], p[minIdx])) {
			minIdx = i;
		}
	}

	return p[minIdx];
}

void test () {
	int arr[] = {4,1,3,2};
	cout << "min number: " << min1(arr, 4) << endl;
	cout << "min number: " << min2(arr, 4, intComp);
	cout << "min number: " << min3(arr, 4, Less());
}