Given a string, find all integers inside and return a string that separates them by commas. There should be no leading or trailing commas. For example, if 11 12 and 13 are in the string, you should return "11,12,13" NOT "11,12,13," or ",11,12,13". If no integers are found, return an empty string.

Complete the following file:

prog.cpp

#include <iostream> #include <string> using namespace std; #include <cctype> #include <iostream> #include <sstream> #include <string> using namespace std; string all_integers(string s) {
}