string Haskell 字符串中的换行符？
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Newline in Haskell String?
提问by Ash
How can I create a newline inside a String? Is it possible without using IO ()?
如何在字符串中创建换行符？不使用可以IO ()吗？
formatRow :: Car -> String
formatRow (a, d:ds, c, x:xs) = a ++ " | " ++ x ++ concat xs ++ " | " ++ show c ++ " | " ++ d ++ concat ds ++ (show '\n')
回答by sepp2k
To create a string containing a newline, just write "\n".
要创建包含换行符的字符串，只需编写"\n".
If you run your program on Windows, it will automatically be convertedto "\r\n".
如果您在 Windows 上运行您的程序，它会自动转换为"\r\n".
Note that calling showon it will escape the newline (or any other meta-characters), so don't do foo ++ (show "\n")or foo ++ (show '\n')- just use foo ++ "\n".
请注意，调用show它会转义换行符（或任何其他元字符），所以不要这样做foo ++ (show "\n")或foo ++ (show '\n')- 只使用foo ++ "\n".
Also note that if you just evaluate a string expression in GHCi without using putStror putStrLn, it will just call showon it, so for example the string "foo\n"will display as "foo\n"in GHCi, but that does not change the fact that it's a string containing a newline and it will print that way, once you output it using putStr.
另请注意，如果您只是在 GHCi 中计算字符串表达式而不使用putStror putStrLn，它只会调用show它，因此例如该字符串"foo\n"将显示为"foo\n"GHCi，但这不会改变它是一个包含换行符的字符串的事实，它一旦您使用putStr.
