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Function `std.stdio.File.byLine`

Returns an input range set up to read from the file handle one line at a time.


						
				auto byLine(Terminator, Char)
				(
				

				  KeepTerminator keepTerminator = No.keepTerminator,
				

				  Terminator terminator = '\n'
				

				)
				

				if (isScalarType!Terminator);
				

				

				auto byLine(Terminator, Char)
				(
				

				  KeepTerminator keepTerminator,
				

				  Terminator terminator
				

				)
				

				if (is(immutable(ElementEncodingType!Terminator) == immutable(Char)));

The element type for the range will be Char[]. Range primitives may throw StdioException on I/O error.

Note

Each front will not persist after popFront is called, so the caller must copy its contents (e.g. by calling to!string) when retention is needed. If the caller needs to retain a copy of every line, use the byLineCopy function instead.

Parameters

Name	Description
Char	Character type for each line, defaulting to `char`.
keepTerminator	Use `Yes.keepTerminator` to include the terminator at the end of each line.
terminator	Line separator (`'\n'` by default). Use `newline` for portability (unless the file was opened in text mode).

Example

import std.algorithm, std.stdio, std.string;
// Count words in a file using ranges.
void main()
{
    auto file = File("file.txt"); // Open for reading
    const wordCount = file.byLine()            // Read lines
                          .map!split           // Split into words
                          .map!(a => a.length) // Count words per line
                          .sum();              // Total word count
    writeln(wordCount);
}

Example

import std.range, std.stdio;
// Read lines using foreach.
void main()
{
    auto file = File("file.txt"); // Open for reading
    auto range = file.byLine();
    // Print first three lines
    foreach (line; range.take(3))
        writeln(line);
    // Print remaining lines beginning with '#'
    foreach (line; range)
    {
        if (!line.empty && line[0] == '#')
            writeln(line);
    }
}

Notice that neither example accesses the line data returned by front after the corresponding popFront call is made (because the contents may well have changed).

Authors

Walter Bright, Andrei Alexandrescu, Alex Rønne Petersen

License

Boost License 1.0.

API Documentation

Function std.stdio.File.byLine

Note

Parameters

Example

Example

Authors

License

Function `std.stdio.File.byLine`