【C++】迭代器與二分查詢

bool search_value_loop(std::vector <int> &ivec,const int search_value,std::vector <int> ::difference_type & position){

 auto start=ivec.cbegin();

 auto end=ivec.cend();

 auto mid=start+(end-start)/2;

// std::cout<<*mid<<std::endl;

 while(mid!=end && *mid!=search_value){

 if(*mid<search_value){

 start=mid+1;

 }else{

 end=mid-1;

 }

 mid=start +(end-start)/2;

 }

 if(*mid==search_value){

 position=mid-ivec.cbegin()+1;

 return true;

 }

 return false;

}

int main()

{

 bool rest;

 vector <int> ::difference_type position;

 vector <int> ivec={1,2,3,4,18,23,85,122};

 rest=search_value_loop(ivec,122,position);

 if(!rest){

 std::cout<<"no match values"<<std::endl;

 }else{

 std::cout<<position<<std::endl;

 }
}