98 lines
2.6 KiB
Zig
98 lines
2.6 KiB
Zig
//
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// Help! Evil alien creatures have hidden eggs all over the Earth
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// and they're starting to hatch!
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//
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// Before you jump into battle, you'll need to know four things:
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//
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// 1. You can attach functions to structs:
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//
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// const Foo = struct{
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// pub fn hello() void {
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// std.debug.print("Foo says hello!\n", .{});
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// }
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// }
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//
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// 2. A function that is a member of a struct is a "method" and is
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// called with the "dot syntax" like so:
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//
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// Foo.hello();
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//
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// 3. The NEAT feature of methods is the special parameter named
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// "self" that takes an instance of that type of struct:
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//
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// const Bar = struct{
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// number: u32,
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//
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// pub fn printMe(self: *Bar) void {
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// std.debug.print("{}\n", .{self.number});
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// }
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// }
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//
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// (Actually, you can name the first parameter anything, but
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// please follow convention and use "self".)
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//
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// 4. Now when you call the method on an INSTANCE of that struct
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// with the "dot syntax", the instance will be automatically
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// passed as the "self" parameter:
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//
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// var my_bar = Bar{ .number = 2000 };
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// my_bar.printMe(); // prints "2000"
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//
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// Okay, you're armed.
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//
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// Now, please zap the alien structs until they're all gone or
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// Earth will be doomed!
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//
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const std = @import("std");
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// Look at this hideous Alien struct. Know your enemy!
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const Alien = struct {
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health: u8,
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// We hate this method:
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pub fn hatch(strength: u8) Alien {
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return Alien{
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.health = strength * 5,
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};
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}
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// We love this method:
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pub fn zap(self: *Alien, damage: u8) void {
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self.health -= if (damage >= self.health) self.health else damage;
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}
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};
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pub fn main() void {
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// Look at all of these aliens of various strengths!
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var aliens = [_]Alien{
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Alien.hatch(2),
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Alien.hatch(1),
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Alien.hatch(3),
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Alien.hatch(3),
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Alien.hatch(5),
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Alien.hatch(3),
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};
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var aliens_alive = aliens.len;
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var heat_ray_strength: u8 = 7; // We've been given a heat ray weapon.
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// We'll keep checking to see if we've killed all the aliens yet.
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while (aliens_alive > 0) {
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aliens_alive = 0;
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// Loop through every alien...
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for (aliens) |*alien| {
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// *** Zap the Alien Here! ***
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alien.zap(heat_ray_strength);
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// If the alien's health is still above 0, it's still alive.
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if (alien.health > 0) aliens_alive += 1;
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}
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std.debug.print("{} aliens. ", .{aliens_alive});
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}
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std.debug.print("Earth is saved!\n", .{});
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}
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