Added lifetimes; split code into library for minigrep.

1 files changed, 43 insertions, 0 deletions

diff --git a/lifetimes/src/main.rs b/lifetimes/src/main.rs
new file mode 100644
index 0000000..87b6ce6
--- /dev/null
+++ b/lifetimes/src/main.rs
@@ -0,0 +1,43 @@
+fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
+    // what this is doing is basically tagging x and y and the
+    // result with the same 'a, telling rust not to let any
+    // of them expire before the others; that way nothing
+    // will go out of scope prematurely and the result will
+    // always have a non-null reference
+
+    // basically, 'a gives all three values the same lifetime.
+    // so long as they're all alive at the same time, there are
+    // no reference errors
+    
+    // note that the lifetime selected for the result is 
+    // equal to the smaller of the lifetimes of the 
+    // parameters
+
+    if x.len() > y.len() {
+        x
+    }
+    else {
+        y
+    }
+}
+
+struct ImportantExcerpt<'a> {
+    part: &'a str,
+}
+
+fn main() {
+    let string1 = String::from("abcd");
+    {
+    let string2 = "xyz";
+
+    let result = longest(string1.as_str(), string2);
+    //dbg!(result);
+    }
+
+    let script = String::from("Before time began, there was the cube. We know not where it comes from.");
+    let first_sentence = script.split('.')
+        .next()
+        .expect("Could not find a '.'");
+    let i = ImportantExcerpt { part: first_sentence };
+    dbg!(i.part);
+}