How to open/create a file/read from a file (n line at a time)/write to a file (in the new Io.Dir)?

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1

All of the topics I’ve searched is std.fs, can you give me a sample of:

  1. Opening/Creating a file in the new (Io.Dir)?

  2. Reading a file (n line at a time)

  3. Writing to a file

I did get into opening a file, but couldn’t give the 2nd parameter (std.Io)?

What i did was

const file = try std.Io.Dir.createFile(std.Io.Dir.cwd(), 'std.Io', cfgfile, .{.read=true});
2

(post deleted by author)

1 Like
3

Here’s my $2c.

const std = @import("std");
const fs = std.fs;

pub fn main() !void {

    // opening or creating a file at a absolute path
    const file = try fs.createFileAbsolute("/tmp/test.txt", .{ .read = true });
    var threaded: std.Io.Threaded = .init_single_threaded;
    const io = threaded.ioBasic();
    const buf_siz = 1024 * 4; // 4K
    var buffer: [buf_siz]u8 = undefined;
    var file_reader = file.reader(io, &buffer);
    var file_writer = file.writer(&buffer);

    // writing to the file
    try file_writer.end();
    try file_writer.interface.writeAll("first line;\n");
    try file_writer.interface.writeAll("second line;\n");
    try file_writer.interface.writeAll("third line.\n");
    try file_writer.interface.flush();

    // reading & printing the lines
    try file_reader.seekTo(0);
    // here I am taking on account that buffer if big enough to hold all lines
    try file_reader.interface.fillMore();
    const new_line = 10;
    var line = (try file_reader.interface.takeDelimiter(new_line)).?;
    std.debug.print("line 1: {s}\n", .{line});
    line = (try file_reader.interface.takeDelimiter(new_line)).?;
    std.debug.print("line 2: {s}\n", .{line});
    line = (try file_reader.interface.takeDelimiter(new_line)).?;
    std.debug.print("line 3: {s}\n", .{line});


    // deleting the created test file
    var dir = try std.fs.openDirAbsolute("/tmp", .{});
    defer dir.close();
    try dir.deleteFile("test.txt");
}
4

@Austin I don’t know, the second param is giving me an error, seems a struct but it needs the vtable field…

note: missing struct field: vtable

@kalapalo What’s the difference between std.fs.Dir.openFile and std.Io.Dir.openFile. I know that std.Io.Dir.openFile is the new way moving forwards…

5

Yeah, std.fs.Dir.Openfile is deprecated and std.Io.Dir.openFile is the way to go.

6

Ah.

My eyes deceived me. I’m very much not using Io.Dir either.
Something I’d update when 16 is no longer dev.

Disregard my answer.