Read file line by line
There is a Reader
type in Zig, which provides various methods to read file, such as readAll
, readInt
, here we will use streamUntilDelimiter
to split lines.
const std = @import("std");
const fs = std.fs;
const print = std.debug.print;
pub fn main() !void {
var gpa = std.heap.GeneralPurposeAllocator(.{}){};
defer _ = gpa.deinit();
const allocator = gpa.allocator();
const file = try fs.cwd().openFile("tests/zig-zen.txt", .{});
defer file.close();
// Wrap the file reader in a buffered reader.
// Since it's usually faster to read a bunch of bytes at once.
var buf_reader = std.io.bufferedReader(file.reader());
const reader = buf_reader.reader();
var line = std.ArrayList(u8).init(allocator);
defer line.deinit();
const writer = line.writer();
var line_no: usize = 1;
while (reader.streamUntilDelimiter(writer, '\n', null)) : (line_no += 1) {
// Clear the line so we can reuse it.
defer line.clearRetainingCapacity();
print("{d}--{s}\n", .{ line_no, line.items });
} else |err| switch (err) {
error.EndOfStream => {}, // Continue on
else => return err, // Propagate error
}
}