mirror of
https://codeberg.org/andyscott/ziglings.git
synced 2024-12-22 22:13:11 -05:00
76 lines
2.3 KiB
Zig
76 lines
2.3 KiB
Zig
// 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 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:
|
|
//
|
|
// const std = @import("std");
|
|
//
|
|
// // 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();
|
|
//
|
|
// const allocator = arena.allocator();
|
|
//
|
|
// const ptr = try allocator.create(i32);
|
|
// std.debug.print("ptr={*}\n", .{ptr});
|
|
//
|
|
// const slice_ptr = try allocator.alloc(f64, 5);
|
|
// std.debug.print("ptr={*}\n", .{ptr});
|
|
// }
|
|
|
|
// 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, each item N should contain the 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
|
|
const allocator = arena.allocator();
|
|
|
|
// allocate memory for this array
|
|
var avg: []f64 = ???;
|
|
|
|
runningAverage(arr, avg);
|
|
std.debug.print("Running Average: ", .{});
|
|
for (avg) |val| {
|
|
std.debug.print("{d:.2} ", .{val});
|
|
}
|
|
std.debug.print("\n", .{});
|
|
}
|
|
|
|
// For more details on memory allocation and the different types of
|
|
// memory allocators, see https://www.youtube.com/watch?v=vHWiDx_l4V0
|