cli_args_handling

cli_args_handling.zig

const std = @import("std");
const process = std.process;
const mem = std.mem;

const usage: []const u8 =
    \\Usage: executable_name [options]
    \\
    \\  -h            Print this help message and exit.
    \\  -c <command>  Run `sh -c <command>` on startup.
    \\
;

//1. iterate arguments: no allocation necessary
pub fn main() anyerror!void {
    var it = std.process.args();
    // Skip our name
    _ = it.nextPosix();
    while (it.nextPosix()) |arg| {
        if (std.mem.eql(u8, arg, "-h")) {
            try std.io.getStdErr().writeAll(usage);
            std.os.exit(0);
        } else {
            try std.io.getStdErr().writeAll(usage);
            std.os.exit(1);
        }
    }
}
//2. save all arguments and free at end of execution
// defer/errdefer: "always run this when exiting scope" or "run this on error when exiting scope"
pub fn main() !void {
    var arena_instance = std.heap.ArenaAllocator.init(std.heap.page_allocator);
    defer arena_instance.deinit(); // this will deinit on error or success

    const arena = &arena_instance.allocator;
    const args = try process.argsAlloc(arena);
    defer process.argsFree(arena, args); // same here

    if (args.len <= 1) {
        var number_or_error: anyerror!i32 = error.ArgNotFound;
        std.log.info("{s}", .{usage});
    }
}