如何在Erlang中读取整数？-HowtoreadintegerinErlang?

1> {ok, [X]} = io:fread("input : ", "~d").
input : 10
{ok,"\n"}
2> X.
10
3> {ok, [A,B]} = io:fread("input : ", "~d,~d").
input : 456,26
{ok,[456,26]}

That's all.

There are various functions in OTP to help you convert a string to an integer. If you just read a string from the user (until newline for example) you can the evaluate it with the function to_integer(String) in the string module:

OTP中有各种函数可以帮助您将字符串转换为整数。如果您只是从用户读取一个字符串(例如直到换行符),您可以使用字符串模块中的函数to_integer(String)来评估它:

string:to_integer(String) -> {Int,Rest} | {error,Reason}

There is also the list_to_integer(String) BIF (Built-In Function, just call without a module) but it is not as forgiving as the string:to_integer(String) function:

还有list_to_integer(String)BIF(内置函数,只是在没有模块的情况下调用),但它不像字符串那样宽容:to_integer(String)函数:

list_to_integer(String) -> int()

You will get a badarg exception if the string does not contain an integer.

如果字符串不包含整数,您将获得badarg异常。

If you use string:to_integer/1, check that the value of Rest is the empty list []. The function extracts the integer, if any, from the beginning of the string. It does not assure that the full input converts to an integer.

如果使用string:to_integer / 1,请检查Rest的值是否为空列表[]。该函数从字符串的开头提取整数(如果有)。它不能保证完整输入转换为整数。

string:to_integer(String) -> {Int,Rest} | {error,Reason}

An example:

{Int, Rest} = string:to_integer("33t").
Int.  % -> 33
Rest. % -> "t"

Why check? If the user's finger slipped and hit 't' instead of 5, then the intended input was 335, not 33.

为什么检查?如果用户的手指滑动并且击中't'而不是5,那么预期的输入是335而不是33。

Try printing the number with ~w instead of ~p:

尝试使用~w而不是~p打印数字:

1> io:format("~w~n", [[10]]).
[10]
ok
2> io:format("~p~n", [[10]]).
"\n"
ok

The ~p format specifier tries to figure out whether the list might be a string, but ~w never guesses; it always prints lists as lists.

~p格式说明符试图弄清楚列表是否可能是一个字符串,但~~从不猜测;它总是将列表打印为列表。

Erlang represents strings as lists of integers that are within a certain range. Therefore the input will be a number that represents the character "1" you could subtract an offset to get the actual. Number, sorry don't have a VM here to test a solution.

Erlang将字符串表示为在特定范围内的整数列表。因此输入将是一个表示字符“1”的数字,您可以减去偏移量以获得实际值。不,抱歉这里没有VM来测试解决方案。