c++ primer 学习笔记10--关联容器

书本376页。练习11.4：单词计数，忽略大小写，与标点。

#include <iostream>
#include <vector>
#include <string>
#include <fstream>
#include <map>
#include <algorithm>
using namespace std;

string& trans(string &s)
{
for (int p = 0; p < s.size(); ++p)
{
if (s[p] >= 'A'&& s[p] <= 'Z')
{
s[p] -= 'A' - 'a';
}
else if (s[p] == ',' || s[p] == '.')
{
s.erase(p, 1);
}

}
return s;
}

int main(int argc,char *argv[])
{
ifstream in(argv[1]);
if (!in)
{
cerr << "打开输入文件失败" << endl;
return -1;
//exit(1);
}
map<string, size_t> word_count;
string word;
while (cin >> word)
{
++word_count[word];
}
for (auto &w : word_count)
{
cout << w.first << "出现了" << w.second << "次" << endl;
}
}

练习11.7

定义一个map,关键字是家庭的姓，保存的是孩子的名。实现添加新的家庭以及向已有的家庭添加孩子。

#include <iostream>
#include <vector>
#include <string>
#include <fstream>
#include <map>
#include <algorithm>
using namespace std;
void add_family(map<string, vector<string>> &families, const string &family)
{
if (families.find(family) != families.end())
{
families[family] = vector<string>();
}
}
void add_child(map<string, vector<string>> &families, const string &family,const string &child)
{
families[family].push_back(child);
}

int main(int argc,char *argv[])
{
map<string, vector<string>> families;
add_family(families, "张");
add_child(families, "张", "强");
add_child(families, "张", "刚");
add_child(families, "王", "五");
add_family(families, "王");

for (auto f : families)
{
cout << f.first << "家的孩子";
for (auto c : f.second)
{
cout << c << " ";
}
cout << endl;
}
}

11.9，定义一个map,将单词与一个行号的list关联，list保存的是单词所在的行号。

#include <iostream>
#include <vector>
#include <string>
#include <fstream>
#include <map>
#include <algorithm>
#include <list>
#include <sstream>
using namespace std;

string& trans(string &s)
{
for (int p = 0; p < s.size(); ++p)
{
if (s[p] >= 'A'&& s[p] <= 'Z')
{
s[p] -= 'A' - 'a';
}
else if (s[p] == ',' || s[p] == '.')
{
s.erase(p, 1);
}

}
return s;
}

int main(int argc, char *argv[])
{
ifstream in(argv[1]);
if (!in)
{
cerr << "打开输入文件失败" << endl;
return -1;
//exit(1);
}

map<string, list<int>> word_lineno;
string line;
string word;
int lineno = 0;
while (getline(in, line))
{
++lineno;//行号增加
istringstream l_in(line);//构造字符串流，读取单词
while (l_in >> word)
{
trans(word);
word_lineno[word].push_back(lineno);
}
}
for (auto &w : word_lineno)
{
cout << w.first << "所在行： " ;
for (auto i : w.second)
{
cout << i << " ";
}
cout << endl;
}
}

11.12.编写程序，读入string 和int的序列，将每个string 和int存入一个pair中，pair保存在一vector中

#include <iostream>
#include <vector>
#include <string>
#include <fstream>
#include <map>
#include <algorithm>
using namespace std;

int main(int argc, char *argv[])
{
ifstream in(argv[1]);
if (!in)
{
cerr << "打开输入文件失败" << endl;
return -1;
//exit(1);
}
vector<pair<string, int>> data;
string s;
int v;
while (in >> s && in >> v)
{
data.push_back(pair<string, int>(s, v));
//data.push_back(make_pair(s,v));
//data.push_back({s,v});
}
for (auto &w : data)
{
cout << w.first << " " << w.second << endl;
}
}