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_archive/rhai_engine/rhaibook/ref/loop.md

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+Infinite Loop
+=============
+
+Infinite loops follow Rust syntax.
+
+`continue` can be used to skip to the next iteration, by-passing all following statements;
+`break` can be used to break out of the loop unconditionally.
+
+```rust
+let x = 10;
+
+loop {
+    x -= 1;
+
+    if x > 5 { continue; }  // skip to the next iteration
+
+    print(x);
+
+    if x == 0 { break; }    // break out of loop
+}
+```
+
+~~~admonish danger.small "Remember the `break` statement"
+
+A `loop` statement without a `break` statement inside its loop block is infinite.
+There is no way for the loop to stop iterating.
+~~~
+
+
+Loop Expression
+---------------
+
+`loop` statements can also be used as _expressions_.
+
+The `break` statement takes an optional expression that provides the return value.
+
+The default return value of a `loop` expression is `()`.
+
+```js
+let x = 0;
+
+// 'loop' can be used just like an expression
+let result = loop {
+    if is_magic_number(x) {
+        // if the loop breaks here, return a specific value
+        break get_magic_result(x);
+    }
+
+    x += 1;
+
+    // ... if the loop exits here, the return value is ()
+};
+
+if result == () {
+    print("Magic number not found!");
+} else {
+    print(`Magic result = ${result}!`);
+}
+```