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Updating wording in 'for' exercises

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This is in preparation for another dive into 'for'
in an upcoming Exercise 100.

Also reformatted 095 for 65 columns and some wording.
This commit is contained in:
Dave Gauer 2023-04-30 16:23:35 -04:00
parent 6b48914d7a
commit e9e6be4e05
3 changed files with 57 additions and 38 deletions
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6
exercises/015_for.zig
View file

@ -23,5 +23,9 @@ pub fn main() void {
std.debug.print("The End.\n", .{}); std.debug.print("The End.\n", .{});
} }
// Note that "for" loops also work on things called "slices" // Note that 'for' loops also work on things called "slices"
// which we'll see later. // which we'll see later.
//
// Also note that 'for' loops have recently become more flexible
// and powerful (two years after this exercise was written).
// More about that in a moment.

6
exercises/016_for2.zig
View file

@ -35,3 +35,9 @@ pub fn main() void {
std.debug.print("The value of bits '1101': {}.\n", .{value}); std.debug.print("The value of bits '1101': {}.\n", .{value});
} }
//
// As mentioned in the previous exercise, 'for' loops have gained
// additional flexibility since these early exercises were
// written. As we'll see in later exercises, the above syntax for
// capturing the index is part of a more general ability. hang in
// there!

83
exercises/095_for_loops.zig
View file

@ -1,47 +1,55 @@
// //
// The Zig language is in rapid development and continuously improves // The Zig language is in rapid development and continuously
// the language constructs steadily. // improves the language constructs. Ziglings evolves with it.
// //
// Since version 0.11, the "for-loops" widely used in other languages // Until version 0.11, Zig's 'for' loops did not directly
// such as C, e.g. "for (int i = 0; i < 10..." can now also be formed // replicate the functionality of the C-style: "for(a;b;c)"
// similarly in Zig, which previously required a "while" construct. // which are so well suited for iterating over a numeric
// Similar in this case actually means better, just as Zig generally // sequence.
// tries to make everything simple and "better".
// //
// These new "for-loops" look like the following in Zig: // Instead, 'while' loops with counters clumsily stood in their
// place:
// //
// for (0..10) |idx| { // var i: usize = 0;
// // In this case 'idx' takes all values from 0 to 9. // while (i < 10) : (i += 1) {
// } // // Here variable 'i' will have each value 0 to 9.
// }
// //
// This is really simple and can replace the previous, somewhat bulky: // But here we are in the glorious future and Zig's 'for' loops
// can now take this form:
// //
// var idx: usize = 0; // for (0..10) |i| {
// while (idx < 10) : (idx += 1) { // // Here variable 'i' will have each value 0 to 9.
// // Again, idx takes all values from 0 to 9. // }
// }
// //
// This would also simplify exercise 13, for example. // The key to understanding this example is to know that '0..9'
// The best way to try this out is to use this exercise, which in the // uses the new range syntax:
// original looks like this:
// //
// ... // 0..10 is a range from 0 to 9
// var n: u32 = 1; // 1..4 is a range from 1 to 3
// //
// // I want to print every number between 1 and 20 that is NOT // At the moment, ranges are only supported in 'for' loops.
// // divisible by 3 or 5. //
// while (n <= 20) : (n += 1) { // Perhaps you recall Exercise 13? We were printing a numeric
// // The '%' symbol is the "modulo" operator and it // sequence like so:
// // returns the remainder after division. //
// if (n % 3 == 0) continue; // var n: u32 = 1;
// if (n % 5 == 0) continue; //
// std.debug.print("{} ", .{n}); // // 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"); const std = @import("std");
// And now with the new "for-loop".
pub fn main() void { pub fn main() void {
// I want to print every number between 1 and 20 that is NOT // I want to print every number between 1 and 20 that is NOT
@ -57,8 +65,9 @@ pub fn main() void {
std.debug.print("\n", .{}); std.debug.print("\n", .{});
} }
//
// Is actually a little easier. The interesting thing here is that the other // That's a bit nicer, right?
// previous 'while' exercises (11,12, 14) cannot be simplified by this //
// new "for-loop". Therefore it is good to be able to use both variations // Of course, both 'while' and 'for' have different advantages.
// accordingly. // Exercises 11, 12, and 14 would NOT be simplified by switching
// a 'while' for a 'for'.