catch and orelse in Zig

Two fallback operators: catch for error unions, orelse for optionals.

const std = @import("std");

pub fn main() void {
    // parseInt returns an error union; catch supplies the fallback.
    const good = std.fmt.parseInt(i32, "42", 10) catch 0;
    const bad = std.fmt.parseInt(i32, "4x2", 10) catch 0;
    std.debug.print("good {d}, bad fell back to {d}\n", .{ good, bad });

    // orelse does the same job for optionals.
    const found = std.mem.indexOf(u8, "causeway", "use");
    const at = found orelse 999;
    std.debug.print("'use' found at index {d}\n", .{at});
}

How it works

1. parseInt(...) catch 0 swallows the parse failure and supplies zero.
2. The good string parses; the bad one falls back, both in one shape.
3. orelse does the identical job when the missing thing is null, not an error.

Keywords and builtins used here

• catch
• const
• fn
• i32
• orelse
• pub
• u8
• void

The run, in numbers

Lines

13

Characters to type

474

Tokens

123

Three-star pace

70 tpm

At the three-star pace of 70 tokens a minute, this run takes about 105 seconds.

Type this snippet

Step 2 of 3 in Errors, step 8 of 27 in Language basics.

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