cs326:formatted_output
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cs326:formatted_output [2018/02/16 14:46] scarl |
cs326:formatted_output [2018/02/16 14:56] scarl |
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| ==== Formatted Output using :io.format ==== | ==== Formatted Output using :io.format ==== | ||
| - | The Erlang library :io includes a ''format'' function that works in a way analogous to ''System.out.printf'', but of course the details are different...very different. One thing in particular, that I tend to forget: the ''format'' function takes two arguments: the format string and a list of zero or more variables and literals to be output. | + | The Erlang library :io includes a ''format'' function that works in a way analogous to ''System.out.printf'', but of course the details are different...very different. One thing in particular, that I tend to forget: the ''format'' function takes two arguments: the format string and a //list// of zero or more variables and literals to be output. |
| We'll explore it in a series of examples: | We'll explore it in a series of examples: | ||
| Line 10: | Line 10: | ||
| :ok | :ok | ||
| - | iex> :io.format("this outputs one Elixir number: ~b~n", [-999]) | + | iex> :io.format("Outputs one Elixir number: ~b~n", [-999]) |
| - | this outputs one Elixir term: -999 | + | Outputs one Elixir number: -999 |
| :ok | :ok | ||
| - | iex> :io.format("this outputs a floating-point number: ~f~n", [5.678]) | + | iex> :io.format("Outputs a floating-point number: ~f~n", [5.678]) |
| - | The number is 5.678 | + | Outputs a floating-point number: 5.678000 |
| :ok | :ok | ||
| - | iex> :io.format("this outputs the same but with just one digit to the right of the decimal: ~3.1f~n", [5.678]) | + | iex> :io.format("Outputs the same but with just 3 digits to the right of the decimal: ~.3f~n", [5.678]) |
| - | The number is 5.7 | + | Outputs the same but with just 3 digits to the right of the decimal: 5.678 |
| :ok | :ok | ||
| - | iex> :io.format("this outputs a floating-point number on a line by itself:~n ~3.1f~n", [5.678]) | + | iex> :io.format("Outputs the same but with field width 3 and just 1 digit right of the decimal: ~3.1f~n", [5.678]) |
| - | The number is | + | Outputs the same but with field width 3 and just 1 digit right of the decimal: 5.7 |
| - | 5.7 | + | :ok |
| + | |||
| + | iex> :io.format("Outputs a floating-point number on a line by itself:~n ~3.1f~n", [5.678]) | ||
| + | Outputs a floating-point number on a line by itself: | ||
| + | 5.7 | ||
| :ok | :ok | ||
| iex> :io.format("this outputs one Elixir term: ~w~n", [:hello]) | iex> :io.format("this outputs one Elixir term: ~w~n", [:hello]) | ||
| this outputs one Elixir term: hello | this outputs one Elixir term: hello | ||
| - | :ok | ||
| - | |||
| - | iex> :io.format("this outputs one Elixir term: ~w~n", ["hello"]) | ||
| - | this outputs one Elixir term: <<104,101,108,108,111>> | ||
| :ok | :ok | ||
| Line 38: | Line 38: | ||
| this outputs two Elixir terms: hello world | this outputs two Elixir terms: hello world | ||
| :ok | :ok | ||
| + | |||
| + | iex> :io.format("~~w outputs any Elixir term: ~w~n", [:hello]) | ||
| + | ~w outputs any Elixir term: hello | ||
| + | :ok | ||
| + | |||
| + | iex> :io.format("~~w outputs any Elixir term: ~w~n", ["hello"]) | ||
| + | ~w outputs any Elixir term: <<104,101,108,108,111>> | ||
| + | :ok | ||
| + | |||
| + | iex> :io.format("~~w outputs any Elixir term: ~w~n", [-999]) | ||
| + | ~w outputs any Elixir term: -999 | ||
| + | :ok | ||
| + | |||
| + | iex> :io.format("~~w outputs any Elixir term: ~w~n", [[1, 2, 3]]) | ||
| + | ~w outputs any Elixir term: [1,2,3] | ||
| + | :ok | ||
| + | iex> | ||
| iex> :io.format("~-15w: ~b degrees C~n", [:moscow, -10]) # ~-15w sets a 15-character field, left justified | iex> :io.format("~-15w: ~b degrees C~n", [:moscow, -10]) # ~-15w sets a 15-character field, left justified | ||
| Line 48: | Line 65: | ||
| </code> | </code> | ||
| - | Complete docs on the :io.format function are on the Erlang library website, but be warned, it is extensive. Note that in Erlang the function is invoked as io::format(...) | + | Complete docs on the :io.format function are on the [[http://erlang.org/doc/man/io.html#format-2|Erlang STDLIB website]], but be warned, it is extensive. Note that in Erlang the function is invoked as io::format(...) |
cs326/formatted_output.txt · Last modified: 2018/02/16 15:00 by scarl
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