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// 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
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