Trying to get user input results in a build error. Zig

Question

I tried getting user input with std.io.getStdIn().reader().readUntilDelimiter(buffer, '\n') but it results in a build error that doesn't provide much help:

Build Summary: 2/5 steps succeeded; 1 failed (disable with --summary none)
install transitive failure
└─ install Test transitive failure
   └─ zig build-exe Test Debug native 1 errors
error: the following build command failed with exit code 1

I simplified the code to the bare minimum but it still presents the same bug:

const std = @import("std");

pub fn main() !void {
    const stdin = std.io.getStdIn().reader();

    const buffer: [1024]u8 = undefined;

    _ = try stdin.readUntilDelimiter(buffer, '\n');
}

Doing anything else without the readUntilDelimiter works fine, it's just the input function that freaks out.

Since the error message provided no help, I tried uninstalling and reinstalling Zig, but that didn't help either. Any help would be greatly appreciated.

Edit: It turns out the build fails just by calling std.io.getStdIn().reader(); without anything else.

zig version ? With 0.13.0, I get the same error message as @sigod — bortzmeyer
– bortzmeyer, Commented Jul 1, 2024 at 9:37

sigod · Accepted Answer · 2024-07-01 07:45:41Z

0

I get this error message:

src\main.zig:8:38: error: array literal requires address-of operator (&) to coerce to slice type '[]u8'
    _ = try stdin.readUntilDelimiter(buffer, '\n');
                                     ^~~~~~

You need to use &buffer instead of buffer. The readUntilDelimiter takes a slice. The & operator coerces an array into a slice.
And declare buffer as var instead of const.

answered Jul 1, 2024 at 7:45

sigod

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2 Comments

YKS Over a year ago

Hi, thanks for your answer. I think that would've been the solution if my computer wasn't weird. My build fails even just by calling std.io.getStdIn().reader(); without anything else, so I think the error has to do with the reader itself.

sigod Over a year ago

Zig is probably complaining about an unused local constant. You need to figure out why you're not seeing error messages.

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