泛型设计的思路：
泛型设计的产生是为了解决 把相同的类或者模板类之间有相似的方法 函数 抽象出来
就是对算法的抽象 迭代器的出现 是为了让抽象后的算法能能够访问不同类的内部数据
而出来的概念函数对象可以理解为 对某一算法的进一步限制提出要求
1.容器
（1）vector 有点类似 动态数组
#include<iostream> #include<vector>//vector #include<iterator>//迭代器 #include<algorithm>//算法 #include<functional>//函数对象 using namespace std; void main() { int a[] = {1,5,3,4,2}; vector<int> v(a,a+5);//vector的构造 // for(int i = 0;i<5;i++) // cout<<v[i]<<endl; //普通的遍历 这里用到了 [] vector<int>::iterator itr;//声明vector迭代器 for(itr = v.begin();itr < v.end();itr++) cout<<*itr<<" ";//通过迭代器遍历 cout<<endl; cout<<v.size()<<endl;//vector的size大小 cout<<v.at(2)<<endl;//at 指定下标返回对应元素值 at的参数是下标 这个是支持随机访问 //访问分为顺序访问和随机访问 不是所有的容器都有随机访问 cout<<v.empty()<<endl;//判断vector是否为空 v.push_back(100);//在vector尾部插入100 for(itr = v.begin();itr < v.end();itr++) cout<<*itr<<" ";//通过迭代器遍历 }注意头文件的使用 (2)stack
#include<iostream> #include<stack> #include<iterator> #include<algorithm> #include<functional> using namespace std; //栈先进后出 void main() { int a; stack<int> s; for(int i = 0;i<5;i++) { cin>>a; s.push(a);//压栈 } cout<<s.top()<<endl; //for( i = 0;i<5;i++) // cout<<s.pop()<<endl; //s.pop()只能弹出 没有返回 pop的值 for( i = 0;i<5;i++) s.pop();//出栈 cout<<s.empty()<<endl;//判断是否为空 }(3).queue
#include<iostream> #include<queue> #include<iterator> #include<algorithm> #include<functional> using namespace std; //队列先进先出 void main() { int a; queue<int> q; for(int i = 0;i < 5;i++) { cin>>a; q.push(a); } cout<<q.front()<<endl;//输出队列头部元素 cout<<q.back()<<endl;//输出队列尾部元素 for( i = 0;i < 5;i++) { q.pop(); } cout<<q.empty()<<endl; }(4)string
#include<iostream> #include<string> #include<iterator> #include<algorithm> #include<functional> using namespace std; void main() { string s1 ="hello",s2("nihao"); cout<<s1.empty()<<endl; cout<<s2.size()<<endl; for(int i = 0;s1[i]!=NULL;i++) cout<<s1[i]; cout<<endl; cout<<s2.at(3)<<endl; string s3 = s1 + s2; cout<<s3<<endl; s3 += s1; cout<<s3<<endl; cout<<s1.substr(1,3)<<endl; cout<<(s1 == s2)<<endl; cout<<(s2 != s1)<<endl; cout<<(s3 > s1)<<endl; cout<<(s3 < s1)<<endl; cout<<(s1 >= s2)<<endl;// hello >= nihao 返回0 cout<<(s1 <= s2)<<endl;//hello <= nihao 返回1 }2.迭代器
vector<int>::iterator itr;//声明vector迭代器 for(itr = v.begin();itr < v.end();itr++) cout<<*itr<<" ";//通过迭代器遍历 3.算法
#include<iostream> #include<vector> #include<iterator> #include<algorithm> #include<functional> using namespace std; void main() { int a[] = {1,5,3,4,2}; vector<int> v(a,a+5);//vector的构造 // for(int i = 0;i<5;i++) // cout<<v[i]<<endl; //普通的遍历 这里用到了 [] vector<int>::iterator itr;//声明vector迭代器 for(itr = v.begin();itr < v.end();itr++) cout<<*itr<<" ";//通过迭代器遍历 cout<<endl; cout<<v.size()<<endl;//vector的size大小 cout<<v.at(2)<<endl;//at 指定下标返回对应元素值 at的参数是下标 这个是支持随机访问 //访问分为顺序访问和随机访问 不是所有的容器都有随机访问 cout<<v.empty()<<endl;//判断vector是否为空 v.push_back(100);//在vector尾部插入100 for(itr = v.begin();itr < v.end();itr++) cout<<*itr<<" ";//通过迭代器遍历 cout<<endl; sort(v.begin(),v.end()); for(itr = v.begin();itr < v.end();itr++) cout<<*itr<<" "; } 对 vector 可以 sort()
sort(v.begin(),v.end()); for(itr = v.begin();itr < v.end();itr++) cout<<*itr<<" ";//这个默认是从小到大排 要它从大到小排要加函数对象对string 也可以sort() sort(s1.begin(),s1.end()); cout<<s1<<endl;find方法
int *pos = find(v.begin(),v.end(),3); if(pos == v.end()) cout<<"Not Found"<<endl;//find 这个算法是 找到元素则返回这个元素 没找到返回最后一个元素的下一个 else cout<<"index = "<<pos - v.begin()<<endl; find_if方法
int isodd(int x) { return x%2; } cout<<*(find_if(v.begin(),v.end(),isodd));//按照isodd的规则查找 找到第一个满足的元素就返回了 count 和 count_if
int b = count(v.begin(),v.end(),3); cout<<endl; cout<<b<<endl; b = count_if(v.begin(),v.end(),isodd); cout<<b<<endl;
4.函数对象
(1)普通函数
#include<iostream> #include<vector> #include<iterator> #include<algorithm> #include<functional> using namespace std; int isbigger(int a,int b) { return (a>b); } void main() { int a[] = {1,5,3,4,2}; vector<int> v(a,a+5);//vector的构造 // for(int i = 0;i<5;i++) // cout<<v[i]<<endl; //普通的遍历 这里用到了 [] vector<int>::iterator itr;//声明vector迭代器 for(itr = v.begin();itr < v.end();itr++) cout<<*itr<<" ";//通过迭代器遍历 cout<<endl; cout<<v.size()<<endl;//vector的size大小 cout<<v.at(2)<<endl;//at 指定下标返回对应元素值 at的参数是下标 这个是支持随机访问 //访问分为顺序访问和随机访问 不是所有的容器都有随机访问 cout<<v.empty()<<endl;//判断vector是否为空 v.push_back(100);//在vector尾部插入100 for(itr = v.begin();itr < v.end();itr++) cout<<*itr<<" ";//通过迭代器遍历 cout<<endl; sort(v.begin(),v.end(),isbigger); for(itr = v.begin();itr < v.end();itr++) cout<<*itr<<" "; }函数对象
int isbigger(int a,int b) { return (a>b); }调用方法 sort(v.begin(),v.end(),isbigger); for(itr = v.begin();itr < v.end();itr++) cout<<*itr<<" "; （2）类
#include<iostream> #include<vector> #include<iterator> #include<algorithm> #include<functional> using namespace std; int isbigger(int a,int b) { return (a>b); } class Big { public: int operator()(int a,int b) { return (a>b); } }; void main() { int a[] = {1,5,3,4,2}; vector<int> v(a,a+5);//vector的构造 // for(int i = 0;i<5;i++) // cout<<v[i]<<endl; //普通的遍历 这里用到了 [] vector<int>::iterator itr;//声明vector迭代器 for(itr = v.begin();itr < v.end();itr++) cout<<*itr<<" ";//通过迭代器遍历 cout<<endl; cout<<v.size()<<endl;//vector的size大小 cout<<v.at(2)<<endl;//at 指定下标返回对应元素值 at的参数是下标 这个是支持随机访问 //访问分为顺序访问和随机访问 不是所有的容器都有随机访问 cout<<v.empty()<<endl;//判断vector是否为空 v.push_back(100);//在vector尾部插入100 for(itr = v.begin();itr < v.end();itr++) cout<<*itr<<" ";//通过迭代器遍历 cout<<endl; sort(v.begin(),v.end(),isbigger); for(itr = v.begin();itr < v.end();itr++) cout<<*itr<<" "; cout<<endl; sort(v.begin(),v.end(),Big()); for(itr = v.begin();itr < v.end();itr++) cout<<*itr<<" "; } 函数对象
class Big { public: int operator()(int a,int b) { return (a>b); } }; 调用方法
sort(v.begin(),v.end(),Big()); for(itr = v.begin();itr < v.end();itr++) cout<<*itr<<" "; 最后用一个复数类来解决
注意 函数对象要能访问到类的数据要用到 友元函数 或者友元类
#include<iostream> #include<iomanip> #include<vector> #include<iterator> #include<algorithm> #include<functional> #include<cmath> using namespace std; class Complex; ostream operator<<(ostream& out,const Complex& c); istream& operator>>(istream& in,Complex& c); Complex Add(const int a,const Complex &c1); Complex Jian(const int a,const Complex &c1); Complex Chen(const int a,const Complex &c1); Complex Chu(const int a,const Complex &c1); int isgreater(Complex x,Complex y); class Complex { friend Complex Add(const int a,const Complex &c1); friend Complex Jian(const int a,const Complex &c1); friend Complex Chen(const int a,const Complex &c1); friend Complex Chu(const int a,const Complex &c1); public: Complex(double r=0, double i=0) :real(r), imag(i){} ~Complex(){} Complex operator+(const Complex& c1)const; Complex operator-(const Complex& c1)const; Complex operator*(const Complex& c1)const; Complex operator/(const Complex& c1)const; Complex operator-(); Complex operator++(); Complex operator++(int); bool operator==(const Complex& c1)const; bool operator!=(const Complex& c1)const; bool operator>(const Complex& c1)const; bool operator<(const Complex& c1)const; friend ostream operator<<(ostream& out, const Complex& c); friend istream& operator>>(istream& in,Complex& c); friend int isgreater(Complex x,Complex y); private: double real; double imag; }; Complex Complex::operator+(const Complex& c1)const { Complex temp; temp.real = real + c1.real; temp.imag = imag + c1.imag; return temp; } Complex Complex::operator-(const Complex& c1)const { Complex temp; temp.real = real - c1.real; temp.imag = imag - c1.imag; return temp; } Complex Complex:: operator*(const Complex& c1)const{ Complex temp; temp.real = real * c1.real; temp.imag = imag * c1.imag; return temp; } Complex Complex:: operator/(const Complex& c1)const { Complex temp; temp.real = real / c1.real; temp.imag = imag / c1.imag; return temp; } Complex Add(const int a,const Complex &c1) { Complex temp; temp.real = a + c1.real; temp.imag = c1.imag; return temp; } Complex Jian(const int a,const Complex &c1) { Complex temp; temp.real = c1.real - a; temp.imag = c1.imag; return temp; } Complex Chen(const int a,const Complex &c1) { Complex temp; temp.real = c1.real * a; temp.imag = c1.imag; return temp; } Complex Chu(const int a,const Complex &c1) { Complex temp; temp.real = c1.real / a; temp.imag = c1.imag; return temp; } Complex Complex::operator-() { return Complex(-real, -imag); } Complex Complex::operator++() { ++real; ++imag; return Complex(real, imag); } Complex Complex::operator++(int) { Complex temp(*this); real++; imag++; return temp; } bool Complex::operator==(const Complex& c1)const { return real == c1.real&&imag == c1.imag; } bool Complex::operator!=(const Complex& c1)const { return real != c1.real && imag != c1.imag; } bool Complex::operator>(const Complex& c1)const { return real > c1.real && imag > c1.imag; } bool Complex:: operator<(const Complex& c1)const { return real < c1.real && imag <c1.imag; } ostream operator<<(ostream& out, const Complex& c) { out <<c.real<<" + "<<c.imag<<"i "; return out; } istream& operator>>(istream& in,Complex& c) { in>>c.real>>c.imag; return in; } int isgreater(Complex x,Complex y) { return sqrt(x.real*x.real+x.imag*x.imag)>sqrt(y.real*y.real+y.imag*y.imag); } void main() { int n; cout<<"请输入复数个数"; cin>>n; vector<Complex> a(n); vector<Complex>::iterator itr; for(itr = a.begin();itr<a.end();itr++) cin>>*itr; sort(a.begin(),a.end(),isgreater); for(itr = a.begin();itr<a.end();itr++) { cout<<*itr<<endl; } }
