[C + +] uses a range-based for loop action string

C++11 provides a scope for statement that iterates through each element in a given sequence and performs some action on each element in the sequence:

forexpression)    statement

• Output each character in a string:

    string str("some string");    for (auto c : str)    {        cout << c << endl;    }

在for循环中使用auto声明变量c，由编译器决定其类型，每次循环，将str中的下一个字符拷贝到c中。

• Use the ISPUNCT function to count the number of punctuation in a string

    string s("Hello World!!!");    decltype0;    for (auto c : s)    {        if (ispunct(c))            ++punct_cnt;    }    cout" punctuation characters in " << s << endl;

• Use the range for statement to change the character of a string

    for (auto &c : s)    {        toupper(c);    }    cout << s << endl;

c是string s中字符的引用，使用toupper将string中字符改成大写字符。

[C + +] uses a range-based for loop action string