Add [&'static and T: 'static] chapter

solutions/lifetime/static.md

@@ -0,0 +1,98 @@
+1、
+```rust
+fn main() {
+    let v: &str = "hello";
+    need_static(v);
+
+    println!("Success!")
+}
+
+fn need_static(r : &'static str) {
+    assert_eq!(r, "hello");
+}
+```
+
+```rust
+fn main() {
+    const v: &str = "hello";
+    need_static(v);
+
+    println!("Success!")
+}
+
+fn need_static(r : &'static str) {
+    assert_eq!(r, "hello");
+}
+```
+
+2、
+```rust
+#[derive(Debug)]
+struct Config {
+    a: String,
+    b: String,
+}
+static mut config: Option<&mut Config> = None;
+
+fn init() -> Option<&'static mut Config> {
+    let c = Box::new(Config {
+        a: "A".to_string(),
+        b: "B".to_string(),
+    });
+
+    Some(Box::leak(c))
+}
+
+
+fn main() {
+    unsafe {
+        config = init();
+
+        println!("{:?}",config)
+    }
+}
+```
+
+3、
+```rust
+fn main() {
+    // Make a `string` literal and print it:
+    let static_string = "I'm in read-only memory";
+    println!("static_string: {}", static_string);
+
+    println!("static_string reference remains alive: {}", static_string);
+}
+```
+
+5、
+```rust
+use std::fmt::Debug;
+
+fn print_it<T: Debug + 'static>( input: T) {
+    println!( "'static value passed in is: {:?}", input );
+}
+
+fn print_it1( input: impl Debug + 'static ) {
+    println!( "'static value passed in is: {:?}", input );
+}
+
+
+fn print_it2<T: Debug + 'static>( input: &T) {
+    println!( "'static value passed in is: {:?}", input );
+}
+
+fn main() {
+    // i is owned and contains no references, thus it's 'static:
+    const i:i32 = 5;
+    print_it(i);
+
+    // oops, &i only has the lifetime defined by the scope of
+    // main(), so it's not 'static:
+    print_it(&i);
+
+    print_it1(&i);
+
+    // but this one WORKS !
+    print_it2(&i);
+}
+```