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rephrase/reformat comments

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Sean Aubin 2023-03-08 12:50:10 -05:00
parent 1be1d854a8
commit f01d9ba92d
1 changed files with 24 additions and 19 deletions
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41
exercises/076a_memory_allocation.zig
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@ -1,20 +1,20 @@
// 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);
@ -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