From 1be1d854a8f690c25a577bef1feb1e9926caf2c7 Mon Sep 17 00:00:00 2001 From: Sean Aubin Date: Tue, 28 Feb 2023 20:54:42 -0500 Subject: [PATCH 1/7] first draft of memory allocation exercise --- build.zig | 4 ++ exercises/076a_memory_allocation.zig | 70 ++++++++++++++++++++++++++++ 2 files changed, 74 insertions(+) create mode 100644 exercises/076a_memory_allocation.zig diff --git a/build.zig b/build.zig index 36668b4..4617515 100644 --- a/build.zig +++ b/build.zig @@ -392,6 +392,10 @@ const exercises = [_]Exercise{ .main_file = "076_sentinels.zig", .output = "Array:123056. Many-item pointer:123.", }, + .{ + .main_file = "076a_memory_allocation.zig", + .output = "Running Average: 0.30 0.25 0.20 0.18 0.22", + }, .{ .main_file = "077_sentinels2.zig", .output = "Weird Data!", diff --git a/exercises/076a_memory_allocation.zig b/exercises/076a_memory_allocation.zig new file mode 100644 index 0000000..b098773 --- /dev/null +++ b/exercises/076a_memory_allocation.zig @@ -0,0 +1,70 @@ +// In most of the examples so far, the inputs are known at compile time, thus +// the amount of memory used by the program is fixed and is requested. However, if responding to +// input whose size is not known at compile time, such as: +// - user input via command-line arguments +// - inputs from another program +// +// You'll need to request memory for you program to be allocated by your +// operating system at runtime. +// +// Zig provides several different allocators. In the Zig documentation, it +// recommends the Arena allocator for simple programs which allocate once and +// then exit: +// +// const std = @import("std"); +// +// // memory allocation can fail because your computer is out of memory, so +// // the return type is !void +// pub fn main() !void { +// +// var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator); +// defer arena.deinit(); +// +// const allocator = arena.allocator(); +// +// const ptr = try allocator.create(i32); +// std.debug.print("ptr={*}\n", .{ptr}); +// +// const slice_ptr = try allocator.create(i32); +// std.debug.print("ptr={*}\n", .{ptr}); +// } + +// Instead of a simple integer, this program requires a slice to be allocated that is the same size as an input array + +// Given a series of numbers, take the running average. In other words, the running average of the last N elements + +const std = @import("std"); + +fn runningAverage(arr: []const f64, avg: [] f64) void { + var sum: f64 = 0; + + for (0.., arr) |index, val| { + sum += val; + avg[index] = sum / @intToFloat(f64, index + 1); + } +} + +pub fn main() !void { + // pretend this was defined by reading in user input + var arr: []const f64 = &[_]f64{ 0.3, 0.2, 0.1, 0.1, 0.4 }; + + // initialize the allocator + var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator); + + // free the memory on exit + defer arena.deinit(); + + // initialize the allocator (TODO: replace this with ???) + const allocator = arena.allocator(); + + // TODO: replace this whole line with ??? + var avg = try allocator.alloc(f64, arr.len); + + runningAverage(arr, avg); + std.debug.print("Running Average: ", .{}); + for (avg) |val| { + std.debug.print("{d:.2} ", .{val}); + } +} + +// For more details on memory allocation and the different types of memory allocators, see https://www.youtube.com/watch?v=vHWiDx_l4V0 From f01d9ba92d8362557aa0e4885d48de5e7975f67d Mon Sep 17 00:00:00 2001 From: Sean Aubin Date: Wed, 8 Mar 2023 12:50:10 -0500 Subject: [PATCH 2/7] rephrase/reformat comments --- exercises/076a_memory_allocation.zig | 43 ++++++++++++++++------------ 1 file changed, 24 insertions(+), 19 deletions(-) diff --git a/exercises/076a_memory_allocation.zig b/exercises/076a_memory_allocation.zig index b098773..ff54edf 100644 --- a/exercises/076a_memory_allocation.zig +++ b/exercises/076a_memory_allocation.zig @@ -1,22 +1,22 @@ -// In most of the examples so far, the inputs are known at compile time, thus -// the amount of memory used by the program is fixed and is requested. However, if responding to -// input whose size is not known at compile time, such as: +// In most of the examples so far, the inputs are known at compile +// time, thus the amount of memory used by the program is fixed. +// However, if responding to input whose size is not known at compile +// time, such as: // - user input via command-line arguments // - inputs from another program // -// You'll need to request memory for you program to be allocated by your -// operating system at runtime. +// You'll need to request memory for your program to be allocated by +// your operating system at runtime. // -// Zig provides several different allocators. In the Zig documentation, it -// recommends the Arena allocator for simple programs which allocate once and -// then exit: +// Zig provides several different allocators. In the Zig +// documentation, it recommends the Arena allocator for simple +// programs which allocate once and then exit: // // const std = @import("std"); // -// // memory allocation can fail because your computer is out of memory, so -// // the return type is !void +// // memory allocation can fail, so the return type is !void // pub fn main() !void { -// +// // var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator); // defer arena.deinit(); // @@ -25,17 +25,21 @@ // const ptr = try allocator.create(i32); // std.debug.print("ptr={*}\n", .{ptr}); // -// const slice_ptr = try allocator.create(i32); +// const slice_ptr = try allocator.create(f64, 5); // std.debug.print("ptr={*}\n", .{ptr}); // } -// Instead of a simple integer, this program requires a slice to be allocated that is the same size as an input array +// Instead of an simple integer or a constant sized slice, this +// program requires a slice to be allocated that is the same size as +// an input array. -// Given a series of numbers, take the running average. In other words, the running average of the last N elements +// Given a series of numbers, take the running average. In other +// words, each item N should contain the average of the last N +// elements. const std = @import("std"); -fn runningAverage(arr: []const f64, avg: [] f64) void { +fn runningAverage(arr: []const f64, avg: []f64) void { var sum: f64 = 0; for (0.., arr) |index, val| { @@ -54,11 +58,11 @@ pub fn main() !void { // free the memory on exit defer arena.deinit(); - // initialize the allocator (TODO: replace this with ???) + // initialize the allocator const allocator = arena.allocator(); - // TODO: replace this whole line with ??? - var avg = try allocator.alloc(f64, arr.len); + // allocate memory for this array instead of empty initialization + var avg: []f64 = {}; runningAverage(arr, avg); std.debug.print("Running Average: ", .{}); @@ -67,4 +71,5 @@ pub fn main() !void { } } -// For more details on memory allocation and the different types of memory allocators, see https://www.youtube.com/watch?v=vHWiDx_l4V0 +// For more details on memory allocation and the different types of +// memory allocators, see https://www.youtube.com/watch?v=vHWiDx_l4V0 From f08af9b24280090c599e30a3ee90b4fbfbcb3aaf Mon Sep 17 00:00:00 2001 From: Sean Aubin Date: Wed, 8 Mar 2023 12:51:07 -0500 Subject: [PATCH 3/7] move memory allocation example to 095 --- build.zig | 8 ++++---- ...6a_memory_allocation.zig => 095_memory_allocation.zig} | 0 2 files changed, 4 insertions(+), 4 deletions(-) rename exercises/{076a_memory_allocation.zig => 095_memory_allocation.zig} (100%) diff --git a/build.zig b/build.zig index 4617515..4f9f046 100644 --- a/build.zig +++ b/build.zig @@ -392,10 +392,6 @@ const exercises = [_]Exercise{ .main_file = "076_sentinels.zig", .output = "Array:123056. Many-item pointer:123.", }, - .{ - .main_file = "076a_memory_allocation.zig", - .output = "Running Average: 0.30 0.25 0.20 0.18 0.22", - }, .{ .main_file = "077_sentinels2.zig", .output = "Weird Data!", @@ -487,6 +483,10 @@ const exercises = [_]Exercise{ .main_file = "095_for_loops.zig", .output = "1 2 4 7 8 11 13 14 16 17 19", }, + .{ + .main_file = "096_memory_allocation.zig", + .output = "Running Average: 0.30 0.25 0.20 0.18 0.22", + }, .{ .main_file = "999_the_end.zig", .output = "\nThis is the end for now!\nWe hope you had fun and were able to learn a lot, so visit us again when the next exercises are available.", diff --git a/exercises/076a_memory_allocation.zig b/exercises/095_memory_allocation.zig similarity index 100% rename from exercises/076a_memory_allocation.zig rename to exercises/095_memory_allocation.zig From 551a36f7c92251e8e035ac9f9f878849af85a459 Mon Sep 17 00:00:00 2001 From: Sean Aubin Date: Wed, 8 Mar 2023 13:09:41 -0500 Subject: [PATCH 4/7] fix allocate example --- exercises/095_memory_allocation.zig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/exercises/095_memory_allocation.zig b/exercises/095_memory_allocation.zig index ff54edf..057b420 100644 --- a/exercises/095_memory_allocation.zig +++ b/exercises/095_memory_allocation.zig @@ -25,7 +25,7 @@ // const ptr = try allocator.create(i32); // std.debug.print("ptr={*}\n", .{ptr}); // -// const slice_ptr = try allocator.create(f64, 5); +// const slice_ptr = try allocator.alloc(f64, 5); // std.debug.print("ptr={*}\n", .{ptr}); // } From a218425ee57d0800fa685d0eb4f5040329a28da2 Mon Sep 17 00:00:00 2001 From: Sean Aubin Date: Wed, 8 Mar 2023 13:21:48 -0500 Subject: [PATCH 5/7] add 095_memory_allocation.patch --- patches/patches/095_memory_allocation.patch | 4 ++++ 1 file changed, 4 insertions(+) create mode 100644 patches/patches/095_memory_allocation.patch diff --git a/patches/patches/095_memory_allocation.patch b/patches/patches/095_memory_allocation.patch new file mode 100644 index 0000000..e13a27a --- /dev/null +++ b/patches/patches/095_memory_allocation.patch @@ -0,0 +1,4 @@ +65c65 +< var avg: []f64 = {}; +--- +> var avg: []f64 = try allocator.alloc(f64, arr.len); From 484822a8da1361d5878c82b0f30eafec1e3bc43e Mon Sep 17 00:00:00 2001 From: Sean Aubin Date: Wed, 8 Mar 2023 13:42:21 -0500 Subject: [PATCH 6/7] rename memory allocation 095 -> 096 --- .../{095_memory_allocation.zig => 096_memory_allocation.zig} | 0 .../{095_memory_allocation.patch => 096_memory_allocation.patch} | 0 2 files changed, 0 insertions(+), 0 deletions(-) rename exercises/{095_memory_allocation.zig => 096_memory_allocation.zig} (100%) rename patches/patches/{095_memory_allocation.patch => 096_memory_allocation.patch} (100%) diff --git a/exercises/095_memory_allocation.zig b/exercises/096_memory_allocation.zig similarity index 100% rename from exercises/095_memory_allocation.zig rename to exercises/096_memory_allocation.zig diff --git a/patches/patches/095_memory_allocation.patch b/patches/patches/096_memory_allocation.patch similarity index 100% rename from patches/patches/095_memory_allocation.patch rename to patches/patches/096_memory_allocation.patch From be87134397d1728b3d98d1229d241254130e0708 Mon Sep 17 00:00:00 2001 From: Sean Aubin Date: Wed, 8 Mar 2023 19:22:17 -0500 Subject: [PATCH 7/7] change empty init to '???' placeholder --- exercises/096_memory_allocation.zig | 4 ++-- patches/patches/096_memory_allocation.patch | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/exercises/096_memory_allocation.zig b/exercises/096_memory_allocation.zig index 057b420..7843b93 100644 --- a/exercises/096_memory_allocation.zig +++ b/exercises/096_memory_allocation.zig @@ -61,8 +61,8 @@ pub fn main() !void { // initialize the allocator const allocator = arena.allocator(); - // allocate memory for this array instead of empty initialization - var avg: []f64 = {}; + // allocate memory for this array + var avg: []f64 = ???; runningAverage(arr, avg); std.debug.print("Running Average: ", .{}); diff --git a/patches/patches/096_memory_allocation.patch b/patches/patches/096_memory_allocation.patch index e13a27a..5398ce5 100644 --- a/patches/patches/096_memory_allocation.patch +++ b/patches/patches/096_memory_allocation.patch @@ -1,4 +1,4 @@ 65c65 -< var avg: []f64 = {}; +< var avg: []f64 = ???; --- > var avg: []f64 = try allocator.alloc(f64, arr.len);