How to resolve the algorithm Read entire file step by step in the Zig programming language

Published on 12 May 2024 09:40 PM
#Zig

How to resolve the algorithm Read entire file step by step in the Zig programming language

Table of Contents

Problem Statement

Load the entire contents of some text file as a single string variable. If applicable, discuss: encoding selection, the possibility of memory-mapping. Of course, in practice one should avoid reading an entire file at once if the file is large and the task can be accomplished incrementally instead (in which case check File IO); this is for those cases where having the entire file is actually what is wanted.

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Read entire file step by step in the Zig programming language

Source code in the zig programming language

const std = @import("std");

const File = std.fs.File;

pub fn main() (error{OutOfMemory} || File.OpenError || File.ReadError)!void {
    var gpa: std.heap.GeneralPurposeAllocator(.{}) = .{};
    defer _ = gpa.deinit();
    const allocator = gpa.allocator();

    const cwd = std.fs.cwd();

    var file = try cwd.openFile("input_file.txt", .{ .mode = .read_only });
    defer file.close();

    const file_content = try file.readToEndAlloc(allocator, comptime std.math.maxInt(usize));
    defer allocator.free(file_content);

    std.debug.print("Read {d} octets. File content:\n", .{file_content.len});
    std.debug.print("{s}", .{file_content});
}

const std = @import("std");

const File = std.fs.File;

pub fn main() (File.OpenError || File.SeekError || std.os.MMapError)!void {
    const cwd = std.fs.cwd();

    var file = try cwd.openFile("input_file.txt", .{ .mode = .read_only });
    defer file.close();

    const file_size = (try file.stat()).size;

    const file_content = try std.os.mmap(null, file_size, std.os.PROT.READ, std.os.MAP.PRIVATE, file.handle, 0);
    defer std.os.munmap(file_content);

    std.debug.print("Read {d} octets. File content:\n", .{file_content.len});
    std.debug.print("{s}", .{file_content});
}

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