From 483fb97dfccca833457f55798149b68942be6deb Mon Sep 17 00:00:00 2001
From: Dave Gauer <dave@ratfactor.com>
Date: Sun, 10 Jan 2021 11:46:42 -0500
Subject: [PATCH] Added Ex 11-14: while loops

---
 11_while.zig  | 33 +++++++++++++++++++++++++++++++++
 12_while2.zig | 33 +++++++++++++++++++++++++++++++++
 13_while3.zig | 30 ++++++++++++++++++++++++++++++
 14_while4.zig | 24 ++++++++++++++++++++++++
 README.md     |  2 +-
 ziglings      |  8 ++++++++
 6 files changed, 129 insertions(+), 1 deletion(-)
 create mode 100644 11_while.zig
 create mode 100644 12_while2.zig
 create mode 100644 13_while3.zig
 create mode 100644 14_while4.zig

diff --git a/11_while.zig b/11_while.zig
new file mode 100644
index 0000000..820cf56
--- /dev/null
+++ b/11_while.zig
@@ -0,0 +1,33 @@
+//
+// Zig 'while' statements create a loop that runs while the
+// condition is true:
+//
+//     while (condition) {
+//         condition = false;
+//     }
+//
+// Remember that the condition must be a boolean value and
+// that we can get a boolean value from conditional operators
+// such as:
+//
+//     a == b   a equals b
+//     a < b    a is less than b
+//     a > b    a is greater than b
+//     a !=b    a does not equal b
+//
+const std = @import("std");
+
+pub fn main() void {
+    var n: u32 = 2;
+
+    while ( ??? ){
+        // Print the current number
+        std.debug.print("{} ", .{n});
+
+        // Set n to n multiplied by 2
+        n *= 2;
+    }
+
+    // Make this print n=1024
+    std.debug.print("n={}\n", .{n});
+}
diff --git a/12_while2.zig b/12_while2.zig
new file mode 100644
index 0000000..dba1a26
--- /dev/null
+++ b/12_while2.zig
@@ -0,0 +1,33 @@
+//
+// Zig 'while' statements can have an optional 'continue expression'
+// which runs every time the while loop continues (either at the
+// end of the loop or when an explicit 'continue' is invoked (we'll
+// try those out next):
+//
+//     while (condition) : (continue expression)
+//         ...
+//     }
+//
+// Example:
+//
+//     var foo = 2;
+//     while (foo<10) : (foo+=2)
+//         // Do something with even numbers less than 10...
+//     }
+//
+// See if you can re-write the last exercise using a continue
+// expression:
+//
+const std = @import("std");
+
+pub fn main() void {
+    var n: u32 = 2;
+
+    while (n < 1000) : ??? {
+        // Print the current number
+        std.debug.print("{} ", .{n});
+    }
+
+    // Make this print n=1024
+    std.debug.print("n={}\n", .{n});
+}
diff --git a/13_while3.zig b/13_while3.zig
new file mode 100644
index 0000000..adb74ef
--- /dev/null
+++ b/13_while3.zig
@@ -0,0 +1,30 @@
+//
+// The last two exercises were functionally identical. Continue
+// expressions really show their utility when used with 'continue'
+// statements!
+//
+// Example:
+//
+//     while (condition) : (continue expression){
+//         if(other condition) continue;
+//         ...
+//     }
+//
+// The continue expression executes even when 'other condition'
+// is true and the loop is restarted by the 'continue' statement.
+//
+const std = @import("std");
+
+pub fn main() void {
+    var n: u32 = 1;
+
+    // I want to print every number between 1 and 20 that is NOT
+    // divisible by 3 or 5.
+    while (n <= 20) : (n+=1) {
+        if(n % 3 == 0) ???;
+        if(n % 5 == 0) ???;
+        std.debug.print("{} ", .{n});
+    }
+
+    std.debug.print("\n", .{});
+}
diff --git a/14_while4.zig b/14_while4.zig
new file mode 100644
index 0000000..e686f88
--- /dev/null
+++ b/14_while4.zig
@@ -0,0 +1,24 @@
+//
+// Continue expressions do NOT execute when a while loop stops
+// because of a 'break' statement.
+//
+// Example:
+//
+//     while (condition) : (continue expression){
+//         if(other condition) break;
+//         ...
+//     }
+//
+const std = @import("std");
+
+pub fn main() void {
+    var n: u32 = 1;
+
+    // Oh dear! This while loop will go forever!?
+    while (true) : (n+=1) {
+        if(???) ???;
+    }
+
+    // Result: we want n=4
+    std.debug.print("n={}\n", .{n});
+}
diff --git a/README.md b/README.md
index f43a95a..ddda73b 100644
--- a/README.md
+++ b/README.md
@@ -63,7 +63,7 @@ Planned exercises:
 * [x] Arrays
 * [x] Strings
 * [x] If
-* [ ] While
+* [x] While
 * [ ] For
 * [ ] Functions
 * [ ] Defer
diff --git a/ziglings b/ziglings
index 2e180f0..1feac45 100755
--- a/ziglings
+++ b/ziglings
@@ -59,6 +59,10 @@ function check_it {
         printf "${fmt_yay}** PASSED **${fmt_off}\n"
     else
         printf "${fmt_err}It seems to compile, but I wanted to see '$correct_output'.${fmt_off}\n"
+        if [[ ! -z "$hint" ]]
+        then
+            echo "$hint"
+        fi
         echo
         exit 1
     fi
@@ -75,6 +79,10 @@ check_it 07_strings2.zig "Ziggy" "Please fix the lyrics!"
 check_it 08_quiz.zig "Program in Zig" "See if you can fix the program!"
 check_it 09_if.zig "Foo is 1!"
 check_it 10_if2.zig "price is \$17"
+check_it 11_while.zig "n=1024" "You probably want a 'less than' condition."
+check_it 12_while2.zig "n=1024" "It might help to look back at the previous exercise."
+check_it 13_while3.zig "1 2 4 7 8 11 13 14 16 17 19"
+check_it 14_while4.zig "n=4"
 
 echo
 echo "    __   __          _ "