C++11-范围for(range for)

for (declaration : expression)
    statement

string str("my string");
for (auto c : str)
    cout<<c<<endl;　　//每行输出str的第一个字符；

#include <iostream>
#include<string>
using namespace std;
int main() {
    string str("This is a cpp_test sample!");
    decltype(str.size()) cnt = 0;　　//类型为string::size_type
    for (auto &c : str) {
        if (ispunct(c))
            cnt++;
        else
            c = toupper(c);
    }
    cout << str << endl << cnt;
}