读书笔记（C++）——【泛型算法】

#include<iostream>
#include<fstream>
#include<sstream>
#include<string>
#include<cctype>
#include<vector>
#include<map>
#include<set>
#include <stdexcept>
#include<stdlib.h>
#include<algorithm>
#include<numeric>
//11.1 概述
//容器内查询某个特定值，vector为例
    int search_value = 42;
    vector<int>::iterator resualt =
        find(vec.begin(),vec.end(),search_value);

    cout<<"the resualt"<<search_value<<(resualt == vec.end()
                         ? "is not present" : "is present");
                       <<endl;
//数组例
    int a[6] = {27,210,12,47,109,83};
    int search_value = 83;
    int *result = find(a,a+6,search_value);
    cout<<"the resualt"<<search_value<<(resualt == a+6
                     ? "is not present" : "is present");
                       <<endl;
//11.2.1 只读算法
    //sum the element in vec starting the summation with the value 42
    int sum = accumulate(vec.begin().vec.end(),42);

    //concatenate element from v and store in sum
    string sum = accumulate(v.begin(),v.end()," "); //第三个参数不能使显式字符串字面值

    // find_first_of的使用
    //统计有多少名字同时出现在两个列表中
    size_t cnt = 0;
    vector<string>::iterator it = roster1.begin();

    while((it = find_first_of(it,roster1.end(),roster2.begin(),
                              roster2.end())) != roster1.end())
    {
        ++cnt;
        ++it;
    }
    cout << "Found " << cnt << " name on both rosters" << endl;
//11.2.2写容器元素的算法

    //1.写入输入序列的元素

    fill(vec.begin(),vec.end(),10);//reset each element to 10;

    //2.不检查写入操作的算法

    vector<int> vec;//empty vector
    //disaster:attempts to write to 10(nonexistent) element in vec;
    fill_n(vec.begin(),10,0);

    //3.引入back_inserter

    vector<int> vec;
    fill_n(back_inserter(vec),10,0);//ok

    //4.写入到目标迭代器的算法

    vector<int> ivec;
    copy(ilist.begin(),ilist.end(),back_inserter(ivec));

    //better way to copy element from list
    vector<int> ivec(list.begin(),list.end());

    //5.算法的_copy版本

    //replace empty vector with value of 0 by 42
    replace(ilst.begin(),ilst.end(),0,42);

    //creat empty vector to hold the replacement
    vector<int> ivec.
    replace_copy(ilst.begin(),ilst.end(),back_inserter(ivec),0,42);

//11.2.3 对容器元素重新排序的算法

    //输入：the quick red fox jumps over the slow red turtle
    //输出:1 word 6 characters or longer

    //去掉重复
    vector<string> words;
    sort(words.begin(),words.end());
    vector<string>::iterator end_unique =
            unique(words.begin,words.end());
    words.erase(end_unique,words.end())

    //定义函数 - 谓词
    bool isShorter(string &s1,string &s2)
    {
        return si.size() < s2.size();
    }

    bool GT6(string &s)
    {
        return s1 >= 6;
    }

    //排序

    //sort word by size,but maintain alphabetic order for word of the same size
    stable_sort(words.begin(),words.end(),isShorter);

    //统计长度不小于6的单词
    vector<string>::size_type wc =
    count_if(words.begin(),words.end(),GT6);

    //完整程序
#include<iostream>
#include<string>
#include<vector>
#include<stdexcept>
#include<stdlib.h>
#include<algorithm>
#include<numeric>


bool isShorter(std::string &s1,std::string &s2)
{
    return (s1.size() < s2.size());
}

bool GT6(std::string &s)
{
    return (s.size() >= 6);
}
    std::string make_plural(size_t ctr,const std::string &word,const std::string &ending)
{
    return (ctr==1)?word:word + ending;
}
int main()
{
    std::vector<std::string> words;
    std::string next_word;
    while(std::cin>>next_word)
    {
        words.push_back(next_word);
    }
    sort(words.begin(),words.end());
    std::vector<std::string>::iterator end_unique =
            unique(words.begin(),words.end());
    words.erase(end_unique,words.end());

    stable_sort(words.begin(),words.end(),isShorter);

    std::vector<std::string>::size_type wc =
    count_if(words.begin(),words.end(),GT6);

    std::cout << wc << " " << make_plural(wc,"word","s")
         << " 6 characters or longer" << std::endl;
    return 0;
}

//11.3.1插入迭代器
1).back_inserter //push_back()实现
2).front_inserter//push_front()实现
3).inserter      //insert实现

        list<int>::iterator it =
            find(ilst.begin(),ilst.end(),42);
        replace_copy(ivec.begin(),ivec.end(),inserter(ilst,it),100,0);

//11.3.2 iostream 迭代器
    //表11 - 1 iostream 迭代器的构造函数
    istream_iterator<T> in(strm);
    istream_iterator<T> in;//istream_iterator超出末端的迭代器
    ostream_iterator<T> in(strm);
    ostream_iterator<T> in(strm,delim);//写入过程中使用dilim作为元素分隔符，delim是以空字符结束的字符数组

    //流迭代器定义

    istream_iterator<int> cin_it(cin);
    istream_iterator<int> end_of_stream;
    ofstream outfile;
    ostream_iterator<Sales_item> output(outfile," ");

    //istream_iterator 迭代器上的操作

    istream_iterator<int> in_iter(cin);
    istream_iterator<int> eof;
    while(in_iter != eof)
        vec.push_back(*in_iter++);

    //等价
    istream_iterator<int> in_iter(cin);
    istream_iterator<int> eof;
    vector<int> vec(in_iter,eof);

    //ostream_iterator对象和istream_iterator对象的使用

    ostream_iterator<string> out_iter(cout," ");
    istream_iterator<string> in_iter(cin),eof;
    while(in_iter != eof)
        *out_iter++ = *in_file++;

    //在类类型上使用istream_iterator

    istream_iterator<Sale_item> item_iter(cin),eof;
    Sale_item sum;
    sum = *item_iter++
    while(item != eof)
    {
        if(item_iter->same_isbn(sum))
            sum = sum + *item_iter;
        else
        {
            cout<<sum<<endl;
            sum = *item_iter;
        }
        ++item_iter;
    }
    cout<<sum<<endl;

    //流迭代器三个限制
    //................

    //与算法一起使用流迭代器
    istream_iterator cin_it(cin);
    istream_iterator eof;
    vector<int> vec(cin_it,eof);
    sort(vec,begin(),vec.end());
    ostream_iterator output(cout," ");
    unique_copy(vec.begin(),vec.end(),output);

//11.3.3 反向迭代器

    vector<int> vec;
    for(int i = 0;i != 10;++i)
    {
        vec.push_back(i);
    }
    vector<int>::reverse_iterator r_iter;
    for(r_iter = vec.rbegin();
        r_iter != vec.rend();++r_iter)
    {
        cout<<*r_iter<<endl;
    }

    //降序排列vector

    sort(vec.rbegin(),vec.rend());

    //反向迭代器与其它迭代器

    //find first element in a comma-separated list
    string::iterator comma = find(line.begin(),line.end(),',');
    cout<<string(line.begin(),comma)<<endl;

    //find last element in a comma-separated list
    string::reverse_iterator rcomma = find(line.rbegin(),line.rend(),',');
    cout<<string(line.rbegin(),rcomma)<<endl;//MIDDLE,LAST -> TSAL
    cout<<string(rcomma.base(),line.end());  //ok

//11.3.4 const 迭代器

//五种迭代器

    //表 11 - 3 迭代器种类
    /*输入迭代器
     *输出迭代器
     *前向迭代器
     *双向迭代器
     *随机访问迭代器
     */

//泛型算法结构

//容器特有算法
    //对于list对象，应该优先使用list容器特有的成员版本，而不是泛型算法

    //表 11 - 4 list 容器特有的操作
    /*
    *lst.merge(lst2)
    *lst.merge(lst2,comp)
    *lst.remove(val)
    *lst.remove_if(unaryPred)
    *lst.reverse()
    *lst.sort()
    *lst.splice(iter,lst2)
    *lst.splice(iter,lst2,iter2)
    *lst.splice(iter,beg,end)
    *lst.unique()
    *lst.unique(binaryPred)
    */