c++学习笔记之 STL 泛型设计

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

#include//vector

#include//迭代器

#include//算法

#include//函数对象

using namespace std;

void main()

{

int a[] = {1,5,3,4,2};

vector v(a,a+5);//vector的构造

// for(int i = 0;i<5;i++)

// cout<

vector::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<

//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.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

using namespace std;

//栈先进后出

void main()

{

int a;

stack s;

for(int i = 0;i<5;i++)

{

cin>>a;

s.push(a);//压栈

}

cout<

//for( i = 0;i<5;i++)

// cout<

for( i = 0;i<5;i++)

s.pop();//出栈

cout<

}

(3).queue

#include

using namespace std;

//队列先进先出

void main()

{

int a;

queue q;

for(int i = 0;i < 5;i++)

{

cin>>a;

q.push(a);

}

cout<

for( i = 0;i < 5;i++)

{

q.pop();

}

cout<

}

(4)string

#include

using namespace std;

void main()

{

string s1 ="hello",s2("nihao");

cout<

for(int i = 0;s1[i]!=NULL;i++)

cout<

string s3 = s1 + s2;

cout<

s3 += s1;

cout<

cout<<(s1 == s2)<

cout<<(s2 != s1)<

cout<<(s3 > s1)<

cout<<(s3 < s1)<

cout<<(s1 >= s2)<= nihao 返回0

cout<<(s1 <= s2)<

}

2.迭代器

vector::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

using namespace std;

void main()

{

int a[] = {1,5,3,4,2};

vector v(a,a+5);//vector的构造

// for(int i = 0;i<5;i++)

// cout<

vector::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<

//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.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<

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<

find方法

int *pos = find(v.begin(),v.end(),3);

if(pos == v.end())

cout<<"Not Found"<

else

cout<<"index = "<

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<

b = count_if(v.begin(),v.end(),isodd);

cout<

4.函数对象

(1)普通函数

#include

using namespace std;

int isbigger(int a,int b)

{

return (a>b);

}

void main()

{

int a[] = {1,5,3,4,2};

vector v(a,a+5);//vector的构造

// for(int i = 0;i<5;i++)

// cout<

vector::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<

//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.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<

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

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 v(a,a+5);//vector的构造

// for(int i = 0;i<5;i++)

// cout<

vector::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<

//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.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<

sort(v.begin(),v.end(),isbigger);

for(itr = v.begin();itr < v.end();itr++)

cout<<*itr<<" ";

cout<

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

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

}

ostream operator<<(ostream& out, const Complex& c)

{

out <

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 a(n);

vector::iterator itr;

for(itr = a.begin();itr

cin>>*itr;

sort(a.begin(),a.end(),isgreater);

for(itr = a.begin();itr

{

cout<<*itr<

}

c++学习笔记之 STL 泛型设计

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