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instance method

IO#each_line

each_line(sep = $/, chomp: false) {|line| ... } → self

each_line(limit, chomp: false) {|line| ... } → self

each_line(sep, limit, chomp: false) {|line| ... } → self

each_line → enumerator

static VALUE
rb_io_each_line(int argc, VALUE *argv, VALUE io)
{
    VALUE str;
    struct getline_arg args;

    RETURN_ENUMERATOR(io, argc, argv);
    prepare_getline_args(argc, argv, &args, io);
    if (args.limit == 0)
        rb_raise(rb_eArgError, "invalid limit: 0 for each_line");
    while (!NIL_P(str = rb_io_getline_1(args.rs, args.limit, args.chomp, io))) {
        rb_yield(str);
    }
    return io;
}

Alias of #each

Calls the block with each remaining line read from the stream; returns self. Does nothing if already at end-of-stream; See Line IO.

With no arguments given, reads lines as determined by line separator $/:

Example

f = File.new('t.txt')
f.each_line {|line| p line }
f.each_line {|line| fail 'Cannot happen' }
f.close

Output:

Example

"First line\n"
"Second line\n"
"\n"
"Fourth line\n"
"Fifth line\n"

With only string argument sep given, reads lines as determined by line separator sep; see Line Separator:

Example

f = File.new('t.txt')
f.each_line('li') {|line| p line }
f.close

Output:

Example

"First li"
"ne\nSecond li"
"ne\n\nFourth li"
"ne\nFifth li"
"ne\n"

The two special values for sep are honored:

Example

f = File.new('t.txt')
# Get all into one string.
f.each_line(nil) {|line| p line }
f.close

Output:

Example

"First line\nSecond line\n\nFourth line\nFifth line\n"

f.rewind
# Get paragraphs (up to two line separators).
f.each_line('') {|line| p line }

Output:

Example

"First line\nSecond line\n\n"
"Fourth line\nFifth line\n"

With only integer argument limit given, limits the number of bytes in each line; see Line Limit:

Example

f = File.new('t.txt')
f.each_line(8) {|line| p line }
f.close

Output:

Example

"First li"
"ne\n"
"Second l"
"ine\n"
"\n"
"Fourth l"
"ine\n"
"Fifth li"
"ne\n"

With arguments sep and limit given, combines the two behaviors:

Calls with the next line as determined by line separator sep.
But returns no more bytes than are allowed by the limit.

Optional keyword argument chomp specifies whether line separators are to be omitted:

Example

f = File.new('t.txt')
f.each_line(chomp: true) {|line| p line }
f.close

Output:

Example

"First line"
"Second line"
""
"Fourth line"
"Fifth line"

Returns an Enumerator if no block is given.

IO#each is an alias for IO#each_line.

See also #each #each_codepoint #echo= #each_char also in 4.1 · 4.0 · 3.4 · 3.3 · 3.1 · 3.0

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