diff --git a/Cargo.lock b/Cargo.lock
index 85b51d1..a3a1692 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -204,6 +204,10 @@ dependencies = [
  "bitflags",
 ]
 
+[[package]]
+name = "refcell-program"
+version = "0.1.0"
+
 [[package]]
 name = "rustc-demangle"
 version = "0.1.21"
@@ -273,6 +277,10 @@ version = "0.1.0"
 name = "stack-program"
 version = "0.1.0"
 
+[[package]]
+name = "str-program"
+version = "0.1.0"
+
 [[package]]
 name = "string-dhat"
 version = "0.1.0"
diff --git a/Cargo.toml b/Cargo.toml
index 33da0a4..3186475 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,2 +1,2 @@
 [workspace]
-members = ["stack-program", "stack-and-heap-program", "string-program", "box-str-program", "string-dhat", "box-str-dhat"]
+members = ["stack-program", "stack-and-heap-program", "string-program", "box-str-program", "string-dhat", "box-str-dhat", "refcell-program", "str-program"]
diff --git a/refcell-program/Cargo.toml b/refcell-program/Cargo.toml
new file mode 100644
index 0000000..6ca9216
--- /dev/null
+++ b/refcell-program/Cargo.toml
@@ -0,0 +1,4 @@
+[package]
+name = "refcell-program"
+version = "0.1.0"
+edition = "2021"
diff --git a/refcell-program/src/main.rs b/refcell-program/src/main.rs
new file mode 100644
index 0000000..31cb573
--- /dev/null
+++ b/refcell-program/src/main.rs
@@ -0,0 +1,9 @@
+use std::cell::RefCell;
+
+fn main() {
+    let refcell_str: RefCell<&str> = RefCell::new("hello");
+
+    println!("refcell_str");
+    let second = refcell_str.clone();
+    println!("refcell_str second:");
+}
diff --git a/str-program/Cargo.toml b/str-program/Cargo.toml
new file mode 100644
index 0000000..28b42e9
--- /dev/null
+++ b/str-program/Cargo.toml
@@ -0,0 +1,4 @@
+[package]
+name = "str-program"
+version = "0.1.0"
+edition = "2021"
diff --git a/str-program/src/main.rs b/str-program/src/main.rs
new file mode 100644
index 0000000..ad9f57c
--- /dev/null
+++ b/str-program/src/main.rs
@@ -0,0 +1,13 @@
+const NAME: &str = "asqar";
+
+fn hello() -> u8 {
+    let hello = NAME;
+    println!("hello {}", hello);
+    0
+}
+
+fn main() {
+    for _ in 1..5 {
+        let v = hello();
+    }
+}
diff --git a/string-program/src/main.rs b/string-program/src/main.rs
index f08a91d..903d4a0 100644
--- a/string-program/src/main.rs
+++ b/string-program/src/main.rs
@@ -1,5 +1,5 @@
 fn main() {
-    let s = String::from("hello!");
+    let s = String::from("hello");
     println!("{}", s);
     println!("size of string on stack: {}", std::mem::size_of_val(&s));
 }