add solutions for basic-types, fix errors

solutions/basic-types/char-bool.md

@@ -0,0 +1,75 @@
+1.
+```rust
+use std::mem::size_of_val;
+fn main() {
+    let c1 = 'a';
+    assert_eq!(size_of_val(&c1),4); 
+
+    let c2 = '中';
+    assert_eq!(size_of_val(&c2),4); 
+} 
+```
+
+2.
+```rust
+fn main() {
+    let c1 = '中';
+    print_char(c1);
+} 
+
+fn print_char(c : char) {
+    println!("{}", c);
+}
+```
+
+3.
+```rust
+fn main() {
+    let _f: bool = false;
+
+    let t = false;
+    if !t {
+        println!("hello, world");
+    }
+} 
+```
+
+4.
+```rust
+fn main() {
+    let f = true;
+    let t = true || false;
+    assert_eq!(t, f);
+}
+```
+
+5.
+```rust
+fn main() {
+    let v0: () = ();
+
+    let v = (2, 3);
+    assert_eq!(v0, implicitly_ret_unit())
+}
+
+fn implicitly_ret_unit() {
+    println!("I will returen a ()")
+}
+
+// don't use this one
+fn explicitly_ret_unit() -> () {
+    println!("I will returen a ()")
+}
+```
+
+6.
+```rust
+use std::mem::size_of_val;
+fn main() {
+    let unit: () = ();
+    // unit type does't occupy any memeory space
+    assert!(size_of_val(&unit) == 0);
+}
+```
+
+

solutions/basic-types/functions.md

@@ -0,0 +1,55 @@
+1.
+```rust
+fn main() {
+    // don't modify the following two lines!
+    let (x, y) = (1, 2);
+    let s = sum(x, y);
+
+    assert_eq!(s, 3);
+}
+
+fn sum(x: i32, y: i32) -> i32 {
+    x + y
+}
+```
+
+2.
+```rust
+fn main() {
+    print();
+}
+
+// replace i32 with another type
+fn print() -> () {
+    println!("hello,world");
+}
+```
+
+3.
+```rust
+fn main() {
+    never_return();
+}
+
+fn never_return() -> ! {
+    // implement this function, don't modify fn signatures
+    panic!("I return nothing!")
+}
+```
+
+```rust
+fn main() {
+    never_return();
+}
+
+use std::thread;
+use std::time;
+fn never_return() -> ! {
+    // implement this function, don't modify fn signatures
+    loop {
+        println!("I return nothing");
+        // sleeping for 1 second to avoid exhausting the cpu resoucre
+        thread::sleep(time::Duration::from_secs(1))
+    }
+}
+```

solutions/basic-types/statements.md

@@ -0,0 +1,47 @@
+1.
+```rust
+fn main() {
+    let v = {
+        let mut x = 1;
+        x += 2
+    };
+ 
+    assert_eq!(v, ());
+ }
+```
+
+```rust
+fn main() {
+    let v = {
+        let mut x = 1;
+        x += 2;
+        x
+    };
+
+    assert_eq!(v, 3);
+}
+```
+
+2.
+```rust
+fn main() {
+    let v = {
+        let x = 3;
+        x
+    };
+ 
+    assert!(v == 3);
+}
+```
+
+3.
+```rust
+fn main() {
+    let s = sum(1 , 2);
+    assert_eq!(s, 3);
+}
+
+fn sum(x: i32, y: i32) -> i32 {
+    x + y
+}
+```