定制操作_2

/**
* 功能:定制操作
* 时间:2014年6月19日07:32:03
* 作者:cutter_point
*/

#include<iostream>
#include<vector>
#include<string>
#include<numeric>
#include<algorithm>

using namespace std;

void elimDups(vector<string> &words)
{
    //按字典顺序排列
    sort(words.begin(), words.end());
    //unique重排输入范围，使每个单词出现一次
    //排列在范围的前部，返回不重复区域之后一个位置的迭代器
    auto end_unique=unique(words.begin(), words.end());
    //使用向量操作erase删除重复单词
    words.erase(end_unique, words.end());
}

//如果ctr的值大于1，返回word的复数形式
string make_plural(size_t ctr, const string &word, const string &ending)
{
    return (ctr>1)?word+ending:word;
}


void biggies(vector<string> &words, vector<string>::size_type sz)
{
    elimDups(words);    //将words按字典顺序排列，删除重复单词
    //按长度排序，长度相同的单词维持字典序
    stable_sort(words.begin(), words.end(),
                [](const string &a, const string &b){return a.size()<b.size();});
    //获取一个迭代器，指向第一个满足size()>=sz的元素
    auto wc=find_if(words.begin(), words.end(),
                    [sz](const string &a){return a.size()>=sz;});
    //计算满足size>=sz的元素的数目
    auto count=words.end()-wc;
    cout<<count<<" "<<make_plural(count, "word", "s")
        <<" of length "<<sz<<" or longer "<<endl;
    //打印长度大于等于给定值的单词，每个单词后面接一个空格
    for_each(wc, words.end(), [](const string &s){cout<<s<<" ";});
    cout<<endl;
}



int main()
{
    vector<string> words={"fox","jumps","over","quick","red","red","slow","the","the","turtle"};
    size_t v1 = 4;

    biggies(words, v1);
    return 0;
}

课后的几个习题

/**
* 功能:编写一个lambda，接受两个int，返回他们的和
* 时间:2014年6月19日08:10:08
* 作者:cutter_point
*/

#include<iostream>
#include<algorithm>
#include<numeric>

using namespace std;

void demo_14()
{
    int a=42;
    int b=38;
    auto c1=[&a,&b]{return a+b;};

    cout<<" a+b= "<<c1()<<endl;
}

void demo_15()
{
    size_t a=38;
    int c=8;
    auto d15=[&a](const int &b){return a+b;};
    cout<<" a+b= "<<d15(c)<<endl;
    a=42;
    auto j=d15(c);
    cout<<" a+b= "<<d15(c)<<" j= "<<j<<endl;
}

int main()
{
    demo_14();
    demo_15();
    return 0;
}

lambda捕获和返回

void biggies(vector<string> &words, vector<string>::size_type sz, ostream &os=cout, char c=' ')
{
    elimDups(words);    //将words按字典顺序排列，删除重复单词
    //按长度排序，长度相同的单词维持字典序
    stable_sort(words.begin(), words.end(),
                [](const string &a, const string &b){return a.size()<b.size();});
    //获取一个迭代器，指向第一个满足size()>=sz的元素
    auto wc=find_if(words.begin(), words.end(),
                    [sz](const string &a){return a.size()>=sz;});
    //计算满足size>=sz的元素的数目
    auto count=words.end()-wc;
    cout<<count<<" "<<make_plural(count, "word", "s")
        <<" of length "<<sz<<" or longer "<<endl;
    //打印长度大于等于给定值的单词，每个单词后面接一个空格
    /*
    for_each(wc, words.end(), [](const string &s){cout<<s<<" ";});
    cout<<endl;
    */
    for_each(words.begin(), words.end(), [&os, c](const string &s){os<<s<<c;});
}