1 string line;
2 while (getline(cin, line))
3     cout << line << endl; 

1 while (getline(cin, line))//如果串不空则输出
2     if (!line.empty())
3         cout << line << endl;
4 while (getline(cin, line))//输出字符数量大于30的串
5     if (line.size > 30)
6         cout << line << endl;

auto len = line.size(); //len的类型就是size_type，不过使用的auto自动确定了类型而不需要事先了解size返回类型

1 isalunm(c)//是字母或数字为真
2 isalpha(c)//是字母为真
3 iscntrl(c)//是控制字符为真
4 isdigit(c)//是数字为真
5 isgraph(c)  // 不是空格但可以打印
6 islower(c)  //是小写？
7 isprint(c)    //是否是可打印的字符
8 tolower(c)    //如果大写字母，转换小写，否则输出
9 toupper(c)    //如果小写字母，转换成对应的大写，否则原本输出

1 string str("some stringA");
2 for (auto c : str)            //对于str中的每一个字符
3     cout << c << endl;    //输出当前字符    

1 string s("hello world!!");
2 decltype(s.size()) punct_cnt = 0;
3 for (auto c : s)
4     if (ispunct(c))
5         ++punct_cot;
6 cout << punct_cnt << "puncts in: " << s << endl;

1 const string hexdigits = "0123456789ABCDEF";
2 string result;
3 string::size_type n;

4 while (cin >> n)
5     if (n < hexdigits.size())
6         result += hexdigits[n];
7 cout << "Your hex number is:" << result << endl;

1 vector<T> v1;              //空
2 vector<T> v2 = v1;         //拷贝初始化
3 vector<T> v2(v1);          //默认初始化
4 vector<T> v3(n, val);      //v3含有n个val初始值
5 vector<T> v4(n);           //v4包含了n个重复执行了初始化的对象
6 vector<T> v5= {a, b, c, ...};//v5包含了初始值个数的原色
7 vector<T> v5 {a, b, c, ...};//等价于上面

vector<string> v1{"hello", "world", "!!!"};//列表初始化
vector<string> v2("hello", "world", "!!!");//错误

1 vector<int> v2;                 //空vector对象
2 for (int i = 0; i != 100; ++i)
3     v2.push_back(i);        //一次把整数值放在v2的尾端

1 string word;
2 vector<string> text;    //空对象
3 while (cin >> word)
4     text.push_back(word);   //把word添加到text后面

1     vector<int> v{1,2,3,4,5,6,7,8,9};
2     for (auto &i : v)
3         i *= i;
4     for (auto i: v)
5         cout << i << " ";
6     cout << endl;

1 vector<unsigned> scores(11, 0);
2 unsigned grade;
3 while (cin >> grade)
4 {
5     if (grade <= 100)
6         ++scores[grade/10];　　//很好的体现了C++代码的简洁性
7 }

1 string s("some string");
2 if (s.begin() != s.end())
3 {
4     auto it = s.begin();
5     *it = toupper(*it);
6 }

1 for (auto it = s.begin(); it != s.end() && !isspace(*it); ++it)
2     *it = toupper(*it);

1 auto beg = text.begin(), end = text.end();
2 auto mid = text.begin() + (end - beg)/ 2;
3 while (mid != end && *mid != sought){
4     if (sought < *mid)
5         end = mid;
6     else
7         beg = mid + 1;
8     mid = beg + (end - beg) / 2;
9 }

 1 #include <iostream>
 2 #include <stdexcept>
 3 using namespace std;
 4 void fun(int a, int b)
 5 {
 6     if (a == b)
 7         throw runtime_error("A == B");
 8     else
 9         throw runtime_error("A != B");
10 }
11 int main()
12 {
13     int x = 1, y = 1;
14     try{
15         fun(x, y);
16     }catch(runtime_error err){
17         cout << err.what();
18     }
19     return 0;
20 }