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authorDave Gauer <dave@ratfactor.com>2023-04-30 17:11:37 -0400
committerDave Gauer <dave@ratfactor.com>2023-04-30 17:11:37 -0400
commitbef099fee6f5a24036d1f02fcc43fe4b849c5528 (patch)
treec7d5ac9b6c2fe41cde1cbfd7ac14f4a86c2fc891 /exercises/095_for3.zig
parentfd10ff8bb3e32ad4c0ef5231cc5f9685d1cd6ca4 (diff)
Renamed 095 to "for3" to match feature sequence
So 100 will be the next in line.
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+//
+// The Zig language is in rapid development and continuously
+// improves the language constructs. Ziglings evolves with it.
+//
+// Until version 0.11, Zig's 'for' loops did not directly
+// replicate the functionality of the C-style: "for(a;b;c)"
+// which are so well suited for iterating over a numeric
+// sequence.
+//
+// Instead, 'while' loops with counters clumsily stood in their
+// place:
+//
+// var i: usize = 0;
+// while (i < 10) : (i += 1) {
+// // Here variable 'i' will have each value 0 to 9.
+// }
+//
+// But here we are in the glorious future and Zig's 'for' loops
+// can now take this form:
+//
+// for (0..10) |i| {
+// // Here variable 'i' will have each value 0 to 9.
+// }
+//
+// The key to understanding this example is to know that '0..9'
+// uses the new range syntax:
+//
+// 0..10 is a range from 0 to 9
+// 1..4 is a range from 1 to 3
+//
+// At the moment, ranges are only supported in 'for' loops.
+//
+// Perhaps you recall Exercise 13? We were printing a numeric
+// sequence like so:
+//
+// var n: u32 = 1;
+//
+// // I want to print every number between 1 and 20 that is NOT
+// // divisible by 3 or 5.
+// while (n <= 20) : (n += 1) {
+// // The '%' symbol is the "modulo" operator and it
+// // returns the remainder after division.
+// if (n % 3 == 0) continue;
+// if (n % 5 == 0) continue;
+// std.debug.print("{} ", .{n});
+// }
+//
+// Let's try out the new form of 'for' to re-implement that
+// exercise:
+//
+const std = @import("std");
+
+pub fn main() void {
+
+ // I want to print every number between 1 and 20 that is NOT
+ // divisible by 3 or 5.
+ for (???) |n| {
+
+ // The '%' symbol is the "modulo" operator and it
+ // returns the remainder after division.
+ if (n % 3 == 0) continue;
+ if (n % 5 == 0) continue;
+ std.debug.print("{} ", .{n});
+ }
+
+ std.debug.print("\n", .{});
+}
+//
+// That's a bit nicer, right?
+//
+// Of course, both 'while' and 'for' have different advantages.
+// Exercises 11, 12, and 14 would NOT be simplified by switching
+// a 'while' for a 'for'.