stl常用算法总结--GeekBand

1.for_each 用法：for_each(容器起始地址，容器结束地址，要执行的方法)
include <iostream>
include <algorithm>
include <vector>
using namespace std;
template<class T>
struct plus2
{
void operator()(T&x)const
{
x+=2;
}
};

void printElem(int& elem)
{
cout << elem << endl;
}

int main()
{
int ia[]={0,1,2,3,4,5,6};
for_each(ia,ia+7,printElem);//输出
int ib[]={7,8,9,10,11,12,13};
vector<int> iv(ib,ib+7);
for_each(iv.begin(),iv.end(),plus2<int>());//更改元素
for_each(iv.begin(),iv.end(),printElem);//输出
return 0;
}

2.find算法
用法：
int *find(int *begin，int *end，int value)
在前闭后合的区间 begin，end中，查找value如果查找到了就返回第一个符合条件的元素，否则返回end指针

include <iostream>
include <algorithm>
using namespace std;
void printElem(int& elem)
{
cout << elem << endl;
}

int main()
{
int ia[]={0,1,2,3,4,5,6};
int *i= find(ia,ia+7,9);//在整个数组中查找元素 9
int *j= find(ia,ia+7,3);//在整个数组中查找元素 3
int end=ia+7;//数组最后位置
if(i == end)
cout<<"没有找到元素 9"<<endl;
else
cout<<"找到元素9"<<endl;
if(j == end)
cout<<"没有找到元素 3"<<endl;
else
cout<<"找到元素"<<j<<endl;
return 0;
}

3. copy算法
   include <iostream>
   include <algorithm>
   include <deque>
   using namespace std;
   template<class T>
   struct display
   {
   void operator()(const T &x)const
   {
   cout<<x<<" ";
   }
   };
   int main()
   {

int ia1[]={0,1,2,3,4,5,6,7,8};
copy(ia1+2,ia1+7,ia1);//将下标2-6复制给 1-5
for_each(ia1,ia1+9,display<int>()); //2,3,4,5,6,5,6,7,8
cout<<endl;
int ia2[]={0,1,2,3,4,5,6,7,8};

copy(ia2+2,ia2+7,ia2+4);//将下标2-6复制给 4-8

for_each(ia2,ia2+9,display<int>()); //0,1,2,3,2,3,4,5,6

cout<<endl;
int ia3[]={0,1,2,3,4,5,6,7,8};

deque<int> id(ia3,ia3+9);

deque<int>::iterator first=id.begin();

deque<int>::iterator last=id.end();

deque<int>::iterator result=id.begin();

++++first;

cout<<*first<<endl;

----last;

cout<<*last<<endl;

cout<<*result<<endl;

copy(first,last,result);

for_each(id.begin(),id.end(),display<int>());//2,3,4,5,6,5,6,7,8

cout<<endl;

int ia4[]={0,1,2,3,4,5,6,7,8};

deque<int> ide(ia4,ia4+9);

deque<int>::iterator first1=ide.begin();

deque<int>::iterator last1=ide.end();

deque<int>::iterator result1=ide.begin();

advance(result1,4);//注意这里跟上面不一样

++++first1;

cout<<*first1<<endl;

----last1;

cout<<*last1<<endl;

cout<<*result1<<endl;

copy(first1,last1,result1);

for_each(ide.begin(),ide.end(),display<int>());// 0,1,2,3,2,3,2,3,2不是预期的 0,1,2,3,2,3,4,5,6

cout<<endl;

return 0;

}