Add a bit more C++ stuff to the C++ app

apps/src/hello-cpp.cpp

@@ -1,6 +1,19 @@
 #include <cstdio>
+#include <string>
+#include <vector>
 
 int main()
 {
-    printf("Well hello world!\n");
+    std::printf("Well hello world!\n");
+
+    std::string str = "this is a c++ string";
+
+    str.append(" yay");
+
+    std::printf("%s\n", str.c_str());
+
+    std::vector<int> vec = {3, 2, 8};
+
+    for (int i : vec) { std::printf("%d ", i); }
+    std::putchar('\n');
 }