如何在Erlang中将整数转换为字符串？ [英] How to convert an integer to a string in Erlang?

问题描述

我知道Erlang中的字符串使用起来会很昂贵。那么如何将 5 转换为 5 ？

I know strings in Erlang can be costly to use. So how do I convert "5"to 5?

是否有像 io：format（〜p，[5]）这样的东西会返回格式化的字符串而不是打印到流中？

Is there anything like io:format("~p",[5]) that would return a formatted string instead of printing to a stream?

推荐答案

以下可能不是最整洁的方法，但它可行：

The following is probably not the neatest way, but it works:

1> lists:flatten(io_lib:format("~p", [35365])).
"35365"

编辑：我发现以下功能很有用：

I've found that the following function comes in useful:

%% string_format/2
%% Like io:format except it returns the evaluated string rather than write
%% it to standard output.
%% Parameters:
%%   1. format string similar to that used by io:format.
%%   2. list of values to supply to format string.
%% Returns:
%%   Formatted string.
string_format(Pattern, Values) ->
    lists:flatten(io_lib:format(Pattern, Values)).

编辑2 （回复评论）：以上功能来自我写了一个小程序来学习Erlang。我在寻找一个字符串格式函数，发现 erl 中的 io_lib：format / 2 的行为与直觉相反，例如：

EDIT 2 (in response to comments): the above function came from a small program I wrote a while back to learn Erlang. I was looking for a string-formatting function and found the behaviour of io_lib:format/2 within erl counter-intuitive, for example:

1> io_lib:format("2 + 2 = ~p", [2+2]).
[50,32,43,32,50,32,61,32,"4"]

当时，我没有意识到@archaelus提到的输出设备的自动展平行为，因此得出结论，上述行为不是我想要的。

At the time, I was unaware of the 'auto-flattening' behaviour of output devices mentioned by @archaelus and so concluded that the above behaviour wasn't what I wanted.

今天晚上，我回到该程序，并用 io_lib：format string_format 函数的调用c>。造成的唯一问题是一些EUnit测试失败，因为它们期望字符串变平。这些很容易修复。

This evening, I went back to this program and replaced calls to the string_format function above with io_lib:format. The only problems this caused were a few EUnit tests that failed because they were expecting a flattened string. These were easily fixed.

我同意@gleber和@womble的观点，即使用此函数将整数转换为字符串是过大的。如果您只需要这些，请使用 integer_to_list / 1 。吻！

I agree with @gleber and @womble that using this function is overkill for converting an integer to a string. If that's all you need, use integer_to_list/1. KISS!

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