---

yaml
---
r: 222863
b: refs/heads/master
c: ffa2121
h: refs/heads/master
i:
  222861: 83456a3
  222859: e13f39c
  222855: 101ac23
  222847: 4c632a0
v: v3

Author: brson

[refs]

@@ -1,5 +1,5 @@
 ---
-refs/heads/master: 0860b29b6a4cc4c150ed2dfb245320527d9a7cc0
+refs/heads/master: ffa21217d2aa41475dd5d14c39f09e17277cf14c
 refs/heads/snap-stage3: a5c12f4e39d32af3c951b66bd2839bc0b5a1125b
 refs/heads/try: b53c0f93eedcdedd4fd89bccc5a3a09d1c5cd23e
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105

trunk/src/doc/trpl/SUMMARY.md

@@ -26,7 +26,8 @@
     * [Primitive Types](primitive-types.md)
     * [Comments](comments.md)
     * [if](if.md)
-    * [Loops](loops.md)
+    * [for loops](for-loops.md)
+    * [while loops](while-loops.md)
     * [Ownership](ownership.md)
     * [References and Borrowing](references-and-borrowing.md)
     * [Lifetimes](lifetimes.md)

trunk/src/doc/trpl/choosing-your-guarantees.md

@@ -308,7 +308,6 @@ scope.
 
 Both of these provide safe shared mutability across threads, however they are prone to deadlocks.
 Some level of additional protocol safety can be obtained via the type system.
-
 #### Costs
 
 These use internal atomic-like types to maintain the locks, which are pretty costly (they can block

trunk/src/doc/trpl/for-loops.md

@@ -0,0 +1,85 @@
+% for Loops
+
+The `for` loop is used to loop a particular number of times. Rust’s `for` loops
+work a bit differently than in other systems languages, however. Rust’s `for`
+loop doesn’t look like this “C-style” `for` loop:
+
+```c
+for (x = 0; x < 10; x++) {
+    printf( "%d\n", x );
+}
+```
+
+Instead, it looks like this:
+
+```rust
+for x in 0..10 {
+    println!("{}", x); // x: i32
+}
+```
+
+In slightly more abstract terms,
+
+```ignore
+for var in expression {
+    code
+}
+```
+
+The expression is an [iterator][iterator]. The iterator gives back a series of
+elements. Each element is one iteration of the loop. That value is then bound
+to the name `var`, which is valid for the loop body. Once the body is over, the
+next value is fetched from the iterator, and we loop another time. When there
+are no more values, the `for` loop is over.
+
+[iterator]: iterators.html
+
+In our example, `0..10` is an expression that takes a start and an end position,
+and gives an iterator over those values. The upper bound is exclusive, though,
+so our loop will print `0` through `9`, not `10`.
+
+Rust does not have the “C-style” `for` loop on purpose. Manually controlling
+each element of the loop is complicated and error prone, even for experienced C
+developers.
+
+# Enumerate
+
+When you need to keep track of how many times you already looped, you can use the `.enumerate()` function.
+
+## On ranges:
+
+```rust
+for (i,j) in (5..10).enumerate() {
+    println!("i = {} and j = {}", i, j);
+}
+```
+
+Outputs:
+
+```text
+i = 0 and j = 5
+i = 1 and j = 6
+i = 2 and j = 7
+i = 3 and j = 8
+i = 4 and j = 9
+```
+
+Don't forget to add the parentheses around the range.
+
+## On iterators:
+
+```rust
+# let lines = "hello\nworld".lines();
+for (linenumber, line) in lines.enumerate() {
+    println!("{}: {}", linenumber, line);
+}
+```
+
+Outputs:
+
+```text
+0: Content of line one
+1: Content of line two
+2: Content of line tree
+3: Content of line four
+```