1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
|
//
// Remember using if/else statements as expressions like this?
//
// var foo: u8 = if (true) 5 else 0;
//
// Zig also lets you use for and while loops as expressions.
//
// Like 'return' for functions, you can return a value from a
// loop block with break:
//
// break true; // return boolean value from block
//
// But what value is returned from a loop if a break statement is
// never reached? We need a default expression. Thankfully, Zig
// loops also have 'else' clauses! As you might have guessed, the
// 'else' clause is evaluated when: 1) a 'while' condition becomes
// false or 2) a 'for' loop runs out of items.
//
// const two: u8 = while (true) break 2 else 0; // 2
// const three: u8 = for ([1]u8{1}) |f| break 3 else 0; // 3
//
// If you do not provide an else clause, an empty one will be
// provided for you, which will evaluate to the void type, which
// is probably not what you want. So consider the else clause
// essential when using loops as expressions.
//
// const four: u8 = while (true) {
// break 4;
// }; // <-- ERROR! Implicit 'else void' here!
//
// With that in mind, see if you can fix the problem with this
// program.
//
const print = @import("std").debug.print;
pub fn main() void {
const langs: [6][]const u8 = .{
"Erlang",
"Algol",
"C",
"OCaml",
"Zig",
"Prolog",
};
// Let's find the first language with a three-letter name and
// return it from the for loop.
const current_lang: ?[]const u8 = for (langs) |lang| {
if (lang.len == 3) break lang;
};
if (current_lang) |cl| {
print("Current language: {s}\n", .{cl});
} else {
print("Did not find a three-letter language name. :-(\n", .{});
}
}
|
