while loops in Zig

The while loop with a continue expression, and one that breaks with a value.

const std = @import("std");

pub fn main() void {
    // The continue expression after : runs at the end of each pass.
    var lap: u32 = 2;
    while (lap <= 8) : (lap += 2) {
        std.debug.print("sled dog lap {d}\n", .{lap});
    }

    // break with a value turns the whole loop into an expression.
    var n: u32 = 1;
    const first_cube = while (n < 100) : (n += 1) {
        if (n * n * n > 300) break n;
    } else 0;
    std.debug.print("first cube past 300: {d}\n", .{first_cube});
}

How it works

1. while (lap <= 8) : (lap += 2) runs the step after every pass.
2. break n hands a value out of the loop, making the loop an expression.
3. The else 0 arm covers the case where the loop ends without breaking.

Keywords and builtins used here

• break
• const
• else
• fn
• if
• pub
• u32
• var
• void
• while

The run, in numbers

Lines

16

Characters to type

445

Tokens

118

Three-star pace

70 tpm

At the three-star pace of 70 tokens a minute, this run takes about 101 seconds.

Type this snippet

Step 2 of 3 in Control flow, step 5 of 27 in Language basics.

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while loops in other languages

• Mojo