C++ Primer 课后习题9.39 统计单词个数并记录最大单词和最短单词

习题9.39： 已知有如下string对象：

string line1 = "We were her pride of 10 she named us:";
string line2 = "Benjamin, Phoenix, the Prodigal";
string line3 = "and perspicacious perspicacious pacific Suzanne";
string sentence = line1 + ‘ ‘ + line2 + ‘ ‘ + line3;

编写程序计算sentence中有多少个单词，并指出其中最长和最短的单词。如果有多个最短或者最长单词，则将他们全部输出。

代码：

 1 #include <iostream>
 2 #include <vector>
 3 #include <list>
 4 #include <string>
 5 #include <deque>
 6 #include <algorithm>
 7 #include <sstream>
 8 using namespace std;
 9
10 int main(int argc, char **argv)
11 {
12     string num("0123456789");
13     string alpha("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ");
14     string alphanum = num + alpha;
15     string line1 = "We were her pride of 10 she named us:";
16     string line2 = "Benjamin, Phoenix, the Prodigal";
17     string line3 = "and perspicacious perspicacious pacific Suzanne";
18     string sentence = line1 + ‘ ‘ + line2 + ‘ ‘ + line3;
19     stringstream ss;
20     ss.str(sentence);
21     string str;
22     string strMax;
23     string strMin;
24     vector<string> vStrMax;
25     vector<string> vStrMin;
26     int sum = 0;
27     while (ss>>str)
28     {
29         sum++;
30         string::size_type pos = 0;
31         //删除非字母字符
32         while ((pos = str.find_first_not_of(alphanum,pos)) != string::npos)
33         {
34             str.erase(pos);
35         }
36         //比较获取最大单词
37         if (str.size() > strMax.size())
38         {
39             strMax = str;
40             vStrMax.clear();
41             vStrMax.push_back(str);
42         }else if (str.size() == strMax.size())
43         {
44             vStrMax.push_back(str);
45         }
46         //比较获取最小单词，注意strMin第一次大小为0
47         if (str.size() < strMin.size() || strMin.size() == 0)
48         {
49             strMin = str;
50             vStrMin.clear();
51             vStrMin.push_back(str);
52         }else if (str.size() == strMin.size())
53         {
54             vStrMin.push_back(str);
55         }
56     }
57     return 0;
58 }

总结：（1）使用字符串流处理字符串，获取单个单词；

　　　（2）使用string的find_first_not_of()方法除去“，：”非单词字符。