var to const when posssible

exercises/010_if2.zig

@@ -1,16 +1,16 @@
 //
 // If statements are also valid expressions:
 //
-//     var foo: u8 = if (a) 2 else 3;
+//     const foo: u8 = if (a) 2 else 3;
 //
 const std = @import("std");
 
 pub fn main() void {
-    var discount = true;
+    const discount = true;
 
     // Please use an if...else expression to set "price".
     // If discount is true, the price should be $17, otherwise $20:
-    var price: u8 = if ???;
+    const price: u8 = if ???;
 
     std.debug.print("With the discount, the price is ${}.\n", .{price});
 }

exercises/016_for2.zig

@@ -29,7 +29,7 @@ pub fn main() void {
         // Note that we convert the usize i to a u32 with
         // @intCast(), a builtin function just like @import().
         // We'll learn about these properly in a later exercise.
-        var place_value = std.math.pow(u32, 2, @intCast(u32, i));
+        const place_value = std.math.pow(u32, 2, @intCast(u32, i));
         value += place_value * bit;
     }
 

exercises/017_quiz2.zig

@@ -13,7 +13,7 @@ const std = import standard library;
 
 function main() void {
     var i: u8 = 1;
-    var stop_at: u8 = 16;
+    const stop_at: u8 = 16;
 
     // What kind of loop is this? A 'for' or a 'while'?
     ??? (i <= stop_at) : (i += 1) {

exercises/023_errors3.zig

@@ -11,8 +11,8 @@ const std = @import("std");
 const MyNumberError = error{TooSmall};
 
 pub fn main() void {
-    var a: u32 = addTwenty(44) catch 22;
-    var b: u32 = addTwenty(4) ??? 22;
+    const a: u32 = addTwenty(44) catch 22;
+    const b: u32 = addTwenty(4) ??? 22;
 
     std.debug.print("a={}, b={}\n", .{ a, b });
 }

exercises/024_errors4.zig

@@ -21,9 +21,9 @@ const MyNumberError = error{
 pub fn main() void {
     // The "catch 0" below is a temporary hack to deal with
     // makeJustRight()'s returned error union (for now).
-    var a: u32 = makeJustRight(44) catch 0;
-    var b: u32 = makeJustRight(14) catch 0;
-    var c: u32 = makeJustRight(4) catch 0;
+    const a: u32 = makeJustRight(44) catch 0;
+    const b: u32 = makeJustRight(14) catch 0;
+    const c: u32 = makeJustRight(4) catch 0;
 
     std.debug.print("a={}, b={}, c={}\n", .{ a, b, c });
 }

exercises/025_errors5.zig

@@ -15,9 +15,9 @@ const MyNumberError = error{
 };
 
 pub fn main() void {
-    var a: u32 = addFive(44) catch 0;
-    var b: u32 = addFive(14) catch 0;
-    var c: u32 = addFive(4) catch 0;
+    const a: u32 = addFive(44) catch 0;
+    const b: u32 = addFive(14) catch 0;
+    const c: u32 = addFive(4) catch 0;
 
     std.debug.print("a={}, b={}, c={}\n", .{ a, b, c });
 }

exercises/031_switch2.zig

@@ -2,7 +2,7 @@
 // What's really nice is that you can use a switch statement as an
 // expression to return a value.
 //
-//     var a = switch (x) {
+//     const a = switch (x) {
 //         1 => 9,
 //         2 => 16,
 //         3 => 7,

exercises/036_enums2.zig

@@ -9,7 +9,7 @@
 // @enumToInt(). We'll learn about builtins properly in a later
 // exercise.
 //
-//     var my_stuff: u8 = @enumToInt(Stuff.foo);
+//     const my_stuff: u8 = @enumToInt(Stuff.foo);
 //
 // Note how that built-in function starts with "@" just like the
 // @import() function we've been using.

exercises/045_optionals.zig

@@ -29,7 +29,7 @@ pub fn main() void {
 
     // Please threaten the result so that answer is either the
     // integer value from deepThought() OR the number 42:
-    var answer: u8 = result;
+    const answer: u8 = result;
 
     std.debug.print("The Ultimate Answer: {}.\n", .{answer});
 }

exercises/047_methods.zig

@@ -78,7 +78,7 @@ pub fn main() void {
     };
 
     var aliens_alive = aliens.len;
-    var heat_ray = HeatRay{ .damage = 7 }; // We've been given a heat ray weapon.
+    const heat_ray = HeatRay{ .damage = 7 }; // We've been given a heat ray weapon.
 
     // We'll keep checking to see if we've killed all the aliens yet.
     while (aliens_alive > 0) {

exercises/059_integers.zig

@@ -18,7 +18,7 @@
 const print = @import("std").debug.print;
 
 pub fn main() void {
-    var zig = [_]u8{
+    const zig = [_]u8{
         0o131, // octal
         0b1101000, // binary
         0x66, // hex

exercises/060_floats.zig

@@ -43,7 +43,7 @@ pub fn main() void {
     //
     // We'll convert this weight from tons to kilograms at a
     // conversion of 907.18kg to the ton.
-    var shuttle_weight: f16 = 907.18 * 2200;
+    const shuttle_weight: f16 = 907.18 * 2200;
 
     // By default, float values are formatted in scientific
     // notation. Try experimenting with '{d}' and '{d:.3}' to see

patches/patches/010_if2.patch

@@ -1,4 +1,4 @@
 13c13
-<     var price: u8 = if ???;
+<     const price: u8 = if ???;
 ---
->     var price: u8 = if (discount) 17 else 20;
+>     const price: u8 = if (discount) 17 else 20;

patches/patches/023_errors3.patch

@@ -1,7 +1,7 @@
 15c15
-<     var b: u32 = addTwenty(4) ??? 22;
+<     const b: u32 = addTwenty(4) ??? 22;
 ---
->     var b: u32 = addTwenty(4) catch 22;
+>     const b: u32 = addTwenty(4) catch 22;
 22c22
 < fn addTwenty(n: u32) ??? {
 ---

patches/patches/045_optionals.patch

@@ -1,4 +1,4 @@
 32c32
-<     var answer: u8 = result;
+<     const answer: u8 = result;
 ---
->     var answer: u8 = result orelse 42;
+>     const answer: u8 = result orelse 42;

patches/patches/060_floats.patch

@@ -1,4 +1,4 @@
 43c43
-<     var shuttle_weight: f16 = 907.18 * 2200;
+<     const shuttle_weight: f16 = 907.18 * 2200;
 ---
->     var shuttle_weight: f32 = 907.18 * 2200.0;
+>     const shuttle_weight: f32 = 907.18 * 2200.0;