finish chapter 3

1 files changed, 67 insertions, 0 deletions

diff --git a/rust/theBook/chapter-3-variables-and-mutability/practice/fibonacci/src/main.rs b/rust/theBook/chapter-3-variables-and-mutability/practice/fibonacci/src/main.rs
new file mode 100644
index 0000000..078f729
--- /dev/null
+++ b/rust/theBook/chapter-3-variables-and-mutability/practice/fibonacci/src/main.rs
@@ -0,0 +1,67 @@
+use std::io;
+use std::process;
+
+fn main() {
+    println!("Print nth Fibonacci number!");
+    println!("");
+
+    print_fibonacci();
+
+    println!("done!");
+}
+
+fn print_fibonacci() {
+    println!("Enter the n you want to print");
+
+    let fib = read_input();
+
+    println!("recursion_fibonacci:");
+    println!("{}", recursion_fibonacci(fib));
+    loop_fibonacci(fib);
+}
+
+fn loop_fibonacci(x: i32) {
+    let mut num1 = 0;
+    let mut num2 = 1;
+    let mut next: i32;
+
+    println!("loop_fibonacci:");
+
+    for _i in 0..x {
+        if _i <= 1 {
+            next = _i;
+        }   else {
+            next = num1 + num2;
+            num1 = num2;
+            num2 = next;
+        }
+        println!("{next}");
+    }
+}
+
+// Not recommend in rust
+fn recursion_fibonacci(x: i32) -> i32 {
+    if x <= 1 {
+        return x;
+    }   else {
+        recursion_fibonacci(x-1) + recursion_fibonacci(x-2)
+    }
+}
+
+fn read_input() -> i32 {
+    let mut inp = String::new();
+
+    io::stdin()
+        .read_line(&mut inp)
+        .expect("failed to read number");
+    
+    let inp: i32 = match inp.trim().parse() {
+        Ok(inp) => inp,
+        Err(_) => {
+            println!("converting error");
+            process::exit(1);
+        },
+    };
+
+    inp
+}