diff --git a/Program.cs b/Program.cs
index 6822aca..e6399ee 100644
--- a/Program.cs
+++ b/Program.cs
@@ -56,7 +56,18 @@ class Program {
                     break;
                 case 4:
                     Console.Clear();
-                    //Input4();
+                    Console.WriteLine("È richiesta la frase in cui effettuare la ricerca");
+                    stringa1 = Input();
+                    Console.WriteLine();
+                    Console.WriteLine("È richiesta la frase che verrà sostituita");
+                    stringa2 = Input();
+                    Console.WriteLine();
+                    if (Controllo2(stringa2, stringa1.Length)) {
+                        Console.WriteLine(TrovaESostituisci(stringa1, stringa2));
+                    }
+                    else {
+                        Console.WriteLine($"Errore: la frase da cercare non può essere più lunga della frase in cui cercare");
+                    }
                     Pausa();
                     break;
                 case 5:
@@ -166,4 +177,24 @@ class Program {
 
         return string.Join(" ", substrings);
     }
+
+    static string TrovaESostituisci(string p_stringa1, string p_stringa2) {
+        string ritorno;
+        const string sostituisci = "*";
+
+        if (p_stringa1.Contains(p_stringa2)) {
+            ritorno = p_stringa1;
+            for (int i = 0; i < p_stringa2.Length; i++) {
+                ritorno = ritorno.Replace(p_stringa2[i], Convert.ToChar(sostituisci));
+            }
+            
+        }
+        else {
+            ritorno = $"Nessuna occorrenza di {p_stringa2} trovata in {p_stringa1}";
+        }
+
+        return ritorno;
+    }
+
+     
 }
diff --git a/bin/Debug/net9.0/strings_3.dll b/bin/Debug/net9.0/strings_3.dll
index c26ffef..3e4cb71 100644
Binary files a/bin/Debug/net9.0/strings_3.dll and b/bin/Debug/net9.0/strings_3.dll differ
diff --git a/bin/Debug/net9.0/strings_3.pdb b/bin/Debug/net9.0/strings_3.pdb
index 2152a9d..fe88fc7 100644
Binary files a/bin/Debug/net9.0/strings_3.pdb and b/bin/Debug/net9.0/strings_3.pdb differ
diff --git a/obj/Debug/net9.0/ref/strings_3.dll b/obj/Debug/net9.0/ref/strings_3.dll
index b9ab9a2..0f2bd7a 100644
Binary files a/obj/Debug/net9.0/ref/strings_3.dll and b/obj/Debug/net9.0/ref/strings_3.dll differ
diff --git a/obj/Debug/net9.0/refint/strings_3.dll b/obj/Debug/net9.0/refint/strings_3.dll
index b9ab9a2..0f2bd7a 100644
Binary files a/obj/Debug/net9.0/refint/strings_3.dll and b/obj/Debug/net9.0/refint/strings_3.dll differ
diff --git a/obj/Debug/net9.0/strings_3.AssemblyInfo.cs b/obj/Debug/net9.0/strings_3.AssemblyInfo.cs
index 9b559bf..ae9f6b9 100644
--- a/obj/Debug/net9.0/strings_3.AssemblyInfo.cs
+++ b/obj/Debug/net9.0/strings_3.AssemblyInfo.cs
@@ -13,7 +13,7 @@ using System.Reflection;
 [assembly: System.Reflection.AssemblyCompanyAttribute("strings_3")]
 [assembly: System.Reflection.AssemblyConfigurationAttribute("Debug")]
 [assembly: System.Reflection.AssemblyFileVersionAttribute("1.0.0.0")]
-[assembly: System.Reflection.AssemblyInformationalVersionAttribute("1.0.0+9786e2adcd46bff810419c77a664ff038d4fb2bd")]
+[assembly: System.Reflection.AssemblyInformationalVersionAttribute("1.0.0+6415a06c85cfa74b112fb81faf09820fc9a42aaf")]
 [assembly: System.Reflection.AssemblyProductAttribute("strings_3")]
 [assembly: System.Reflection.AssemblyTitleAttribute("strings_3")]
 [assembly: System.Reflection.AssemblyVersionAttribute("1.0.0.0")]
diff --git a/obj/Debug/net9.0/strings_3.AssemblyInfoInputs.cache b/obj/Debug/net9.0/strings_3.AssemblyInfoInputs.cache
index a0c2987..4e9c5da 100644
--- a/obj/Debug/net9.0/strings_3.AssemblyInfoInputs.cache
+++ b/obj/Debug/net9.0/strings_3.AssemblyInfoInputs.cache
@@ -1 +1 @@
-62074303f49b761550171178f383c453b8b19d1e02f472014128ddf26529322b
+daf4d26f162aad74b0d6ca9d5e46d1f534c7df8294bd270db72667436b646006
diff --git a/obj/Debug/net9.0/strings_3.dll b/obj/Debug/net9.0/strings_3.dll
index c26ffef..3e4cb71 100644
Binary files a/obj/Debug/net9.0/strings_3.dll and b/obj/Debug/net9.0/strings_3.dll differ
diff --git a/obj/Debug/net9.0/strings_3.pdb b/obj/Debug/net9.0/strings_3.pdb
index 2152a9d..fe88fc7 100644
Binary files a/obj/Debug/net9.0/strings_3.pdb and b/obj/Debug/net9.0/strings_3.pdb differ