int main()
{
	string s1("Hello");
	cout << s1 << endl; //Hello

	string s2(8, 'x');
	cout << s2 << endl; //xxxxxxxx
    
	string month = "March";
	cout << month << endl; //March
    
	string s;
	s = 'n';
	cout << s << endl; //n
    
    string error('n'); //error
    
	return 0;
}

string s1("hello"), s2("hello"), s2("hell");
int f1 = s1.compare(s2); //0 (hello == hello)

int f2 = s1.compare(s3); //1 (hello > hell)

int f3 = s3.compare(s1); //-1 (hell < hello)

int f4 = s1.compare(1, 2, s3, 0, 3); //-1 (el < hell)

int f5 = s1.compare(0, s1.size(), s3); //1 (hello > hell)

string s1("hello world"), s2;
s2 = s1.substr(4,5); //下标4开始的5个字符

cout << s2 << endl; //o wor

string s1("hello world"), s2("really");
s1.swap(s2); 
cout << s1 << endl; //really

cout << s2 << endl; //hello world

string s1("hello world");
cout << s1.find("ll") << endl; //2

cout << s1.find("abc") << endl; //4294967295(strin::npos)

cout << s1.rfind("ll") << endl; //9

cout << s1.rfind("abc") << endl; //4294967295(strin::npos)

cout << s1.find_first_of("abcde") << endl; //1

cout << s1.find_first_of("abc") << endl; //4294967295(strin::npos)

cout << s1.find_last_of("abcde") << endl; //11

cout << s1.find_last_of("abc") << endl; //4294967295(strin::npos)

cout << s1.find_first_not_of("abcde") << endl; //0

cout << s1.find_first_not_of("hello world") << endl; //4294967295(strin::npos)

cout << s1.find_last_not_of("abcde") << endl; //10

cout << s1.find_last_not_of("hello world") << endl; //4294967295(strin::npos)

string s1("hello world");
s1.erase(5); //去掉下标5及之后的字符

cout << s1 << " " << s1.length() << " " << s1.size() << endl; //hello 5 5

s1 = "hello world";
s1.replace(2, 3, "haha"); //将s1中下标2开始的3个字符换成“haha”

cout << s1 << endl; //hehaha world

s1 = "hello world";
s1.replace(2, 3, "haha", 1, 2); //将s1中下标2开始的3个字符换成“haha”中下标1开始的2个字符

cout << s1 << endl; //heah world

string s1("hello world");
string s2("show insert");
s1.insert(5, s2); //将s2插入到s1下标5的位置

cout << s1 << endl; //helloshow insert world

s1.insert(2, s2, 5, 3); //将s2中下标5开始的3个字符插入s1下标2的位置

cout << s1 << endl; //heinslloshow insert world

string s1("hello world");
printf("%s\n", s1.c_str()); //s1.c_str()返回传统的const char *类型字符串，且该字符串以 '\0' 结尾

//输出：hello world

string s1("hello world");
const char *p1 = s1.data();
for(int i = 0;i < s1.length(); ++i)
    printf("%c", *(p1 + i)); //s1.data()返回一个char *类型字符串，对s1的修改可能会使p1出错

//输出：hello world

string s1("hello world");
int len = s1.length();
char * p2 = new char[len + 1];
s1.copy(p2, 5, 0); //从s1的下标0的字符开始，制作一个最长5个字符长度的字符串副本，并将其赋值给p2。返回值表明实际复制的字符串的长度

p2[5] = 0;
cout << p2 << endl; //hello

#include <string>
#include <iostream>
#include <sstream>

int main()
{
    //istringstream示例
    
	string input("Input test 123 4.7 A");
	istringstream inputString(input);
	string string1, string2;
	int i;
	double d;
	char c;
	inputString >> string1 >> string2 >> i >> d >> c;
	cout << string1 << endl; //Input
    
	cout << string2 << endl; //test
    
	cout << i << endl; //123 
    
	cout << d << endl; //4.7 
    
	cout << c << endl; //A
    
	long L;
	if (inputString >> L)
		cout << "long\n";
	else
		cout << "empty\n"; //empty
    
    //ostringstream示例
    
    ostringstream outputString;
	int a = 10;
	outputString << "This" << a << "ok" << endl;
	cout << outputString.str(); //This 10ok
    
	return 0;
}

#include <iostream>
#include <algorithm>
using namespace std;

class A {
	int v;
public:
	A(int n) :v(n) { }
	bool operator < (const A & a2) const {
		//必须为常量成员函数
        
		cout << v << "<" << a2.v << "?" << endl;
		return false;
	}
	bool operator == (const A & a2) const {
		//必须为常量成员函数
        
		cout << v << "==" << a2.v << "?" << endl;
		return v == a2.v;
	}
};

int main()
{
	A a[] = { A(1),A(2) ,A(3) ,A(4) ,A(5) };
	cout << binary_search(a, a + 4, A(9)); //折半查找
    
	return 0;
}

//输出：

//3<9?

//2<9?

//1<9?

//9<1?

//1

class CMyAverage {
public:
	double operator()(int a1, int a2, int a3) {
		//重载()运算符
        
		return (double)(a1 + a2 + a3) / 3;
	}
};

int main()
{
	CMyAverage average; //函数对象
    
	cout << average(3, 2, 3); // average.operator()(3, 2, 3) 用起来看上起像函数调用
    
	//输出 2.6667
    
	return 0;
}

template<class InIt, class T, class Pred>
T accumulate(InIt first, InIt last, T val, Pred pr);

//Dev C++ 中 Accumulate 源代码1：

template<typename _InputIterator, typename _Tp>
_Tp accumulate(_InputIterator _first, _InputIterator _last, _Tp _init) {
	for (; _first!= _last; ++_first)
		_init = _init + *_first;
	return _init;
}

//Dev C++ 中 Accumulate 源代码2：

template<typename _InputIterator, typename _Tp, typename _BinaryOperation>
_Tp accumulate(_InputIterator _first, _InputIterator _last, _Tp _init, _BinaryOperation _binary_op) {
	for (; _first!= _last; ++_first)
		_init = _binary_op(_init, *_first);
	return _init;
}

int sumSquares(int total, int value) {
	return total + value * value;
}

template<class T>
void PrintInterval(T first, T last) {
	//输出区间[first, last)中的元素
    
	for (; first != last; ++first)
		cout << *first << " ";
	cout << endl;
}

template<class T>
class SumPowers {
private:
	int power;
public:
	SumPowers(int p) :power(p) {}
	const T operator()(const T & total, const T & value) {
		//计算value的power次方，加到total上
        
		T v = value;
		for (int i = 0; i < power - 1; ++i)
			v = v * value;
		return total + v;
	}
};

int main()
{
	const int SIZE = 10;
	int a1[] = { 1,2,3,4,5,6,7,8,9,10 };
	vector<int> v(a1, a1 + SIZE);
	cout << "1) ";
	PrintInterval(v.begin(), v.end());
	int result = accumulate(v.begin(), v.end(), 0, sumSquares);
	cout << "2) 平方和：" << result << endl;
	result = accumulate(v.begin(), v.end(), 0, SumPowers<int>(3));
	cout << "3) 立方和：" << result << endl;
	result = accumulate(v.begin(), v.end(), 0, SumPowers<int>(4));
	cout << "4) 4次方和：" << result << endl;
	return 0;
}

//输出：

//1) 1 2 3 4 5 6 7 8 9 10

//2) 平方和：385

//3) 立方和：3025

//4) 4次方和：25333

//其中accumulate实例化出：
int accumulate(vector<int>::iterator first, vector<int>::iterator last, int init, int (*op)(int, int)){
    for(;first != last;++first)
        init = op(init, *first);
    return init;
}