I want to use a structure to handle `argv` and `env`, but I don't know how to do it

[silver ibex]

As the title suggests, I want to separate argv and env from the main() function and handle them separately, but I am inexperienced and do not know how to operate them

const std = @import("std");

pub fn main() !void {
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    const allocator = gpa.allocator();
    defer {
        const deinit_status = gpa.deinit();
        if (deinit_status == .leak) @panic("TEST FAIL");
    }

    const argv = try std.process.argsAlloc(allocator);
    defer std.process.argsFree(allocator, argv);

    const env = std.os.environ;

    for (argv) |value| {
        std.debug.print("{s}", .{value});
    }

    for (env) |value| {
        std.debug.print("{s}", .{value});
    }
}

[tropic flint]

std.os.environ and std.process.argsAlloc are not tied to the main function, you can access them wherever you want

[weary marten]

well to be clear, std.os.environ is tied to the startup code, it will be undefined if you create your own startup code

same with std.process.argsAlloc

but yeah, you can use them anywhere of course (assuming you're using the main function)

[silver ibex]

Forgive me for my lack of ability. It seems that I am unable to write a program that can compile or run normally. Can you help me?

I estimate that I only need an example of creating and destroying, and I may understand how to do it

[weary marten]

what errors are you getting?

[silver ibex]

Such as type errors, incorrect memory releases, etc. There was indeed a version before that could not run normally during compilation, but it made me feel too frustrated. I have already deleted it

[weary marten]

i recommend you try again, and whenever you hit an error your dont understand, post it here

[tropic flint]

does the program above not work?
to separate getting the environment and program arguments from main, simply put them in their own functions. do notice that std.process.argsAlloc requires an allocator (the usual pattern is for the function to require a std.mem.Allocator argument), and the result should also be freed after use

[silver ibex]

envParameter.zig

const std = @import("std");

pub const envParameter = struct {
    arg: []const [:0]u8,
    env: [][*]u8,

    pub fn get(allocator: std.mem.Allocator) !envParameter {
        const arg = try std.process.argsAlloc(allocator);
        const env = std.os.environ;
        return envParameter{ .arg = arg, .env = env };
    }

    pub fn del(self: envParameter, allocator: std.mem.Allocator) void {
        std.process.argsFree(allocator, self.arg);
    }
};

main.zig

const std = @import("std");
const envParameter = @import("envParameter.zig");

pub fn main() !void {
    var gpa = std.heap.GeneralPurposeAllocator(.{}){};
    const allocator = gpa.allocator();
    defer {
        const deinit_status = gpa.deinit();
        if (deinit_status == .leak) @panic("TEST FAIL");
    }

    const p = try envParameter.envParameter.get(allocator);

    for (p.arg) |value| {
        std.debug.print("{s}", .{value});
    }

    for (p.env) |value| {
        std.debug.print("{s}", .{value});
    }
    p.del(allocator);
}

install
└─ install RAZOR
   └─ zig build-exe RAZOR Debug native 1 errors
C:\Users\Raum\AppData\Local\Microsoft\WinGet\Packages\zig.zig_Microsoft.Winget.Source_8wekyb3d8bbwe\zig-windows-x86_64-0.13.0\lib\std\mem.zig:756:57: error: invalid type given to std.mem.span: [*]u8       
                .Many => if (ptr_info.sentinel == null) @compileError("invalid type given to std.mem.span: " ++ @typeName(T)),
                                                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
C:\Users\Raum\AppData\Local\Microsoft\WinGet\Packages\zig.zig_Microsoft.Winget.Source_8wekyb3d8bbwe\zig-windows-x86_64-0.13.0\lib\std\mem.zig:782:31: note: called from here
pub fn span(ptr: anytype) Span(@TypeOf(ptr)) {
                          ~~~~^~~~~~~~~~~~~~
referenced by:
    format__anon_7274: C:\Users\Raum\AppData\Local\Microsoft\WinGet\Packages\zig.zig_Microsoft.Winget.Source_8wekyb3d8bbwe\zig-windows-x86_64-0.13.0\lib\std\fmt.zig:185:23
    print__anon_4520: C:\Users\Raum\AppData\Local\Microsoft\WinGet\Packages\zig.zig_Microsoft.Winget.Source_8wekyb3d8bbwe\zig-windows-x86_64-0.13.0\lib\std\io\Writer.zig:24:26
    remaining reference traces hidden; use '-freference-trace' to see all reference traces
error: the following command failed with 1 compilation errors:
C:\Users\Raum\AppData\Local\Microsoft\WinGet\Packages\zig.zig_Microsoft.Winget.Source_8wekyb3d8bbwe\zig-windows-x86_64-0.13.0\zig.exe build-exe -ODebug -Mroot=C:\Users\Raum\Documents\rz\RAZOR\src\main.zig --cache-dir C:\Users\Raum\Documents\rz\RAZOR\.zig-cache --global-cache-dir C:\Users\Raum\AppData\Local\zig --name RAZOR --listen=-
Build Summary: 2/5 steps succeeded; 1 failed (disable with --summary none)
install transitive failure
└─ install RAZOR transitive failure
   └─ zig build-exe RAZOR Debug native 1 errors

error: the following build command failed with exit code 1:
C:\Users\Raum\Documents\rz\RAZOR\.zig-cache\o\83d4a787f2972ef8aa51f89f0140834d\build.exe C:\Users\Raum\AppData\Local\Microsoft\WinGet\Packages\zig.zig_Microsoft.Winget.Source_8wekyb3d8bbwe\zig-windows-x86_64-0.13.0\zig.exe C:\Users\Raum\Documents\rz\RAZOR C:\Users\Raum\Documents\rz\RAZOR\.zig-cache C:\Users\Raum\AppData\Local\zig --seed 0xf923367f -Z1b8a870c5a6a3dcb

[weary marten]

yeah you can't print a [][*]u8 with the stdlib formatter

so the p.env printing stuff

[tropic flint]

the env field in envParameter should probably have type [][*:0]u8 - that is, sentinel terminated

[weary marten]

yes

[silver ibex]

How can I fix this error

[tropic flint]

change the type of the env field.
the error is due to std.debug.print not knowing how to print a [*]u8 as a string - very reasonable, since the type has no indication for the number of characters in the string.
by changing the type to [][*:0]u8 (that is, a slice of pointers to sequences of u8s, terminated with 0s), the printing function will know how to obtain the length of the strings (by searching for the 0 sentinel)

[silver ibex]

Thank you so much, the program has finally run successfully. I have gained a new understanding of Zig!

[tropic flint]

you're welcome ^-^

also I think you've found a bug...

this is covariance over mutable references

a classic type system unsoundness

well, I'll call this an oversight, not bug

still, I'll look into that - it might be worth opening an issue about

and here's the issue:

test {
    var x: [*:0]const u8 = "abc";
    const good_ref: *[*:0]const u8 = &x;
    const evil_ref: *[*]const u8 = good_ref; // this coercion is bad!

    evil_ref.* = @as([*]const u8, &.{ 'a', 'b', 'c' });
    // oops! `x` is now storing a
    // non-sentinel-terminated pointer!
}

gonna file a bug report about it

I have reported on a similar issue before, Imma just append this example to it

[silver ibex]

It was several months before I saw your important comment😲
I have indeed discovered some aspects of the code now
But when I wanted to replace it with other std code, I found that there were a lot of methods in the library
I don't know which library to use, so I came to ask you specifically

[weary marten]

library for what?

[silver ibex]

This should be a translation error
Look at the picture
Which function should I use to solve the problem

[weary marten]

what’s your problem exactly?

[silver ibex]

You said before,
well to be clear, std.os.environ is tied to the startup code, it will be undefined if you create your own startup code
That is to say, it is unusable, so I need to find an alternative solution in std, but I don't know which one to use