find,find_if,count,count_if,search_n，search使用浅析

find,和find_if用于容器查找某个值，返回是迭代器。其中关联容器是基于二叉树的，它有自己更高性能的成员函数find和find_if  [count和count_if也是一样的]

STL这东西，得多敲代码，多理解，原谅我的惰性，我可直接贴代码了。推荐一个网站，可以根据头文件找函数，里面可以找到所有algorithm函数原型和例子：

http://www.cplusplus.com/reference/algorithm/

#include<iostream>#include<vector>#include<string>#include<algorithm>#include<functional>using namespace std;bool isoushu(int elem){return elem%2==0;}int main(){int a[]={1,2,3,4,5,6,7,8,4,10};vector<int>v(a,a+10);int num=count(v.begin(),v.end(),4);cout<<num<<endl;int oushu=count_if(v.begin(),v.end(),isoushu);cout<<oushu<<endl;int dayu5=count_if(v.begin(),v.end(),bind2nd(greater<int>(),5));cout<<dayu5<<endl;system("pause");return 0;}

#include<iostream>#include<string>#include<vector>#include<algorithm>#include<functional>#include<cmath>using namespace std;bool absLess(int& a,int& b){return abs(a)<abs(b);}int main(){int a[]={-17,-4,-3,-2,-1,0,1,2,3,4,5,6,7,8,9,10};vector<int>v(a,a+15);int maxnumber=*max_element(v.begin(),v.end());cout<<"max "<<maxnumber<<endl;int minnumber=*min_element(v.begin(),v.end());cout<<"min "<<minnumber<<endl;int zhengfumax=*max_element(v.begin(),v.end(),absLess);cout<<"zhengfumax "<<zhengfumax<<endl;int zhengfumin=*min_element(v.begin(),v.end(),absLess);cout<<"zhengfumin "<<zhengfumin<<endl;system("pause");return 0;}

#include<iostream>#include<string>#include<vector>#include<algorithm>#include<functional>#include<cmath>using namespace std;bool absLess(int& a,int& b){return abs(a)<abs(b);}int main(){int a[]={-17,-4,-3,-2,-1,0,1,2,3,4,5,6,7,8,9,10};vector<int>v(a,a+15);vector<int>::iterator it;it=find(v.begin(),v.end(),4);cout<<distance(v.begin(),it)<<endl;cout<<*it<<endl;vector<int>::iterator it1=find(v.begin(),v.end(),-4);vector<int>::iterator it2=find(v.begin(),v.end(),4);if(it1!=v.end()&&it2!=v.end()){copy(it1,++it2,ostream_iterator<int>(cout," "));cout<<endl;}system("pause");return 0;}

#include<iostream>#include<string>#include<vector>#include<algorithm>#include<functional>#include<cmath>using namespace std;bool beisanzhengchu(int elem){return elem%3==0;}int main(){int a[]={-17,-4,-3,-2,-1,0,1,2,3,4,5,6,7,8,9,10};vector<int>v(a,a+15);vector<int>::iterator it=v.begin();while((it=find_if(it,v.end(),beisanzhengchu))!=v.end()){cout<<*it<<"\t";++it;}cout<<endl;it=v.begin();while((it=find_if(it,v.end(),bind2nd(greater<int>(),6)))!=v.end()){cout<<*it<<"\t";++it;}cout<<endl;system("pause");return 0;}

#include<iostream>#include<string>#include<vector>#include<algorithm>#include<functional>#include<cmath>using namespace std;int main(){int a[]={1,2,3,4,5,6,7,7,7,7,8,8,8,9,10};vector<int>v(a,a+15);vector<int>::iterator it;it=search_n(v.begin(),v.end(),2,8);cout<<distance(v.begin(),it)<<endl;cout<<*(--it)<<endl;cout<<"********************"<<endl;it=v.begin();it=search_n(v.begin(),v.end(),3,6,greater<int>());cout<<*it<<endl;system("pause");return 0;}

#include<iostream>#include<string>#include<vector>#include<algorithm>#include<functional>#include<cmath>using namespace std;bool isoushu(int elem,int){//包装了一下，把二元函数封装成一元，理解一下。return elem%2==0;}int main(){int a[]={1,2,3,4,5,6,7,7,7,7,8,8,8,9,10};vector<int>v(a,a+15);vector<int>::iterator it=v.begin();it=search_n(v.begin(),v.end(),3,0,isoushu);cout<<distance(v.begin(),it)<<endl;system("pause");return 0;}

 

#include<iostream>#include<string>#include<vector>#include<list>#include<algorithm>using namespace std;int main(){int a[]={1,2,3,4,5,6,7,8,9,10};vector<int>v(a,a+10);vector<int>vv(a+2,a+8);for(vector<int>::iterator itera=v.begin();itera!=v.end();++itera){cout<<*itera<<" ";}cout<<endl;for(vector<int>::iterator iterb=vv.begin();iterb!=vv.end();++iterb){cout<<*iterb<<" ";}cout<<endl;vector<int>::iterator it=search(v.begin(),v.end(),vv.begin(),vv.end());if(it!=v.begin()){cout<<"v include vv"<<endl;}else{cout<<"v not include vv"<<endl;}cout<<*it<<endl;system("pause");return 0;}

#include<iostream>#include<string>#include<vector>#include<algorithm>using namespace std;int main(){int a[]={1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10};vector<int>v(a,a+20);vector<int>vv(a+3,a+8);for(vector<int>::iterator itera=v.begin();itera!=v.end();++itera){cout<<*itera<<" ";}cout<<endl;for(vector<int>::iterator iterb=vv.begin();iterb!=vv.end();++iterb){cout<<*iterb<<" ";}cout<<endl;vector<int>::iterator it;it=search(v.begin(),v.end(),vv.begin(),vv.end());while(it!=v.end()){cout<<"found the local "<<distance(v.begin(),it)<<endl;++it;it=search(it,v.end(),vv.begin(),vv.end());}system("pause");return 0;}

#include<iostream>#include<string>#include<vector>#include<algorithm>using namespace std;bool checkeven(int elem,bool even){if(even){return elem%2==0;}else{return elem%2==1;}}int main(){int a[]={1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10};vector<int>v(a,a+20);vector<int>vv(a+3,a+8);bool check[3]={true,false,true};vector<int>::iterator it;it=search(v.begin(),v.end(),check,check+3,checkeven);while(it!=v.end()){cout<<"found"<<*it<<endl;++it;it=search(it,v.end(),check,check+3,checkeven);}system("pause");return 0;}

#include<iostream>#include<string>#include<vector>#include<algorithm>using namespace std;int main(){int a[]={1,2,3,4,5,6,7,8,9,10,1,2,3,4,5,6,7,8,9,10};vector<int>v(a,a+20);vector<int>vv(a+3,a+8);vector<int>::iterator end=v.end();vector<int>::iterator it;it=find_end(v.begin(),v.end(),vv.begin(),vv.end());while(it!=end){cout<<"found "<<distance(v.begin(),it)<<endl;end=it;it=find_end(v.begin(),end,vv.begin(),vv.end());}system("pause");return 0;}

上面的代码都能运行，琢磨琢磨。