。。

简单记录下我的学习过程 (代码为主)

find 、 find_if

/**********************线性查找O(n)find();find_if();注意：    1.假设是已序区间，能够使用区间查找算法    2.关联式容器(set,map)有等效的成员函数find();时间复杂度O(log(n))    3.string 有等效的成员函数find();**********************/#include<iostream>#include<cstdio>#include<string>#include<vector>#include<set>#include<algorithm>#include<functional>using namespace std;/*************************************************************************************std::find                                                                    algorithm--------------------------------------------------------------------------------------template <class InputIterator, class T>   InputIterator find ( InputIterator first, InputIterator last, const T& value );eg:template<class InputIterator, class T>  InputIterator find ( InputIterator first, InputIterator last, const T& value )  {    for ( ;first!=last; first++) if ( *first==value ) break;    return first;  }**************************************************************************************//*************************************************************************************std::find_if                                                                    algorithm--------------------------------------------------------------------------------------template <class InputIterator, class Predicate>   InputIterator find_if ( InputIterator first, InputIterator last, Predicate pred );eg:template<class InputIterator, class Predicate>  InputIterator find_if ( InputIterator first, InputIterator last, Predicate pred )  {    for ( ; first!=last ; first++ ) if ( pred(*first) ) break;    return first;  }**************************************************************************************/bool IsEven (int i);int main (){    int myints[] = {10,30,20,40,20,10,30,40};    int * p;    // pointer to array element:    p = find(myints,myints+8,30);    ++p;    cout << "The element following 30 is " << *p << endl;    vector<int> myvector (myints,myints+8);    vector<int>::iterator it;    // iterator to vector element:    it = find (myvector.begin(), myvector.end(), 30);    ++it;    cout << "The element following 30 is " << *it << endl;    //输出第一个30---第二个30区间内的数    vector<int>::iterator it2;    it2=find (it,myvector.end(),30);    while(it!=it2)        cout<<*it++<<" ";    cout<<endl;/**--------------------------------find_if()---------------------------------**///找第一个偶数    it = find_if (myvector.begin(), myvector.end(), IsEven);//函数 或 函数对象    cout << "The first odd value is " << *it << endl;    it2 = find_if(myvector.begin(),myvector.end(), not1(bind2nd(modulus<int>(),2)));    cout << "The first odd value is " << *it2 << endl;/**--------------------------------关联容器---------------------------------**/    set<int> s(myvector.begin(),myvector.begin()+4);    cout<<"复杂度为O(log(n))，查找*s.find(40)：= " << *s.find(40) << endl;/**---------------------------------string----------------------------------**/    string st("AngelaBaby");    string::size_type pos = st.find("Baby");    if(pos != string::npos)        cout<<"find it!"<<endl;    else cout<<"not find it!"<<endl;    pos = st.find("baby");    if(pos != string::npos)        cout<<"find it!"<<endl;    else cout<<"not find it!"<<endl;    return 0;}bool IsEven (int i){  return ((i%2)==0);}/******Output:    The element following 30 is 20    The element following 30 is 20    20 40 20 10    The first odd value is 10    The first odd value is 10    复杂度为O(log(n))，查找*s.find(40)：= 40    find it!    not find it!******/