format code in md

solutions/compound-types/array.md

@@ -1,4 +1,5 @@
 1.
+
 ```rust
 fn main() {
     let arr: [i32; 5] = [1, 2, 3, 4, 5];
@@ -8,12 +9,13 @@ fn main() {
 ```
 
 2.
+
 ```rust
 fn main() {
     // we can ignore parts of the array type or even the whole type, let the compiler infer it for us
     let arr0 = [1, 2, 3];
     let arr: [_; 3] = ['a', 'b', 'c'];
-    
+
     // Arrays are stack allocated, `std::mem::size_of_val` return the bytes which array occupies
     // A char takes 4 byte in Rust: Unicode char
     assert!(std::mem::size_of_val(&arr) == 12);
@@ -21,6 +23,7 @@ fn main() {
 ```
 
 3.
+
 ```rust
 fn main() {
     let list: [i32; 100] = [1; 100];
@@ -31,6 +34,7 @@ fn main() {
 ```
 
 4.
+
 ```rust
 fn main() {
     // fix the error
@@ -39,10 +43,11 @@ fn main() {
 ```
 
 5.
+
 ```rust
 fn main() {
     let arr = ['a', 'b', 'c'];
-    
+
     let ele = arr[0];
 
     assert!(ele == 'a');
@@ -50,10 +55,11 @@ fn main() {
 ```
 
 6.
+
 ```rust
 fn main() {
     let names = [String::from("Sunfei"), "Sunface".to_string()];
-    
+
     // `get` returns an Option<T>, it's safe to use
     let name0 = names.get(0).unwrap();