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ocaml - 如何将用户输入值添加到 Ocaml 中的数组

问题描述

我在 OCaml 工作，必须解决以下问题

7.1 Problem 1 – Number of values less than average
Input: An integer, listlen, followed by listlen number of integer values.
Output: The list of values, number of items on the list, and the number of input values that are less than the average of all the values
Sample input:
Enter the count and the corresponding integer values:
7 10 60 3 55 15 45 40
Corresponding output:
The list:
10 60 3 55 15 45 40
The average:
32.57
Number of values less than average:
3

这个想法是使用用户输入，获取要平均的数字长度，获取要平均的数字，平均它们，然后告诉列表中哪些数字小于平均值。我的问题在于尝试将用户给出的值添加到数组中。我能够创建数组，但不知道使用什么代码来添加值。

我目前的代码...

(* Prompts the user to enter the number of values they want to average
then gets that number and prints it *)
print_string "Enter The Number of Values You Want To Average:\n";;
let n_values = Scanf.scanf "%d" (fun n -> n);;
Printf.printf "%d\n" n_values;;

(* Prompts the user to enter the numbers they want averaged then
adds those values to an array and prints the numbers *)
print_string "Enter The Values To Be Averaged:\n";;
let a = Array.make n_values 0;;

for i = 0 to Array.length a - 1 do
    (*let values = Scanf.scanf "%d" (fun n -> n)*)
    a.(i) <- i
  done;;

for i = 0 to Array.length a - 1 do
    Printf.printf "%i" a.(i);
done;;

(* Adds each of the values of the array together, stores it in sum and then divides by the n_values initialized above and stores in average, then prints this value *)
print_string "\nThe Average:\n";;
let sum = Array.fold_left (+) 0 a;;
let average = sum / n_values;;
Printf.printf "%d\n" average;;

(* Checks which numbers in the array are less than the computed average and increments a counter if it is less*)
print_string "The Number of Values Less Than The Average:\n";;
let counter = ref 0;;
for i = 0 to Array.length a - 1 do
   if a.(i) < average then incr counter;
done;;
Printf.printf "%d\n" !counter;;

有问题的代码是...

let a = Array.make n_values 0;;

for i = 0 to Array.length a - 1 do
    (*let values = Scanf.scanf "%d" (fun n -> n)*)
    a.(i) <- i
  done;;

for i = 0 to Array.length a - 1 do
    Printf.printf "%i" a.(i);
done;;

我已经尝试了当前注释掉的内容，a.(i) <- values但没有添加，它给了我一个错误 Fatal error: exception Scanf.Scan_failure("scanf: bad input at char number 1: character ' ' is not a decimal digit")

标签： ocaml

解决方案

如果您包含注释掉的代码，您将拥有：

let values = Scanf.scanf "%d" (fun n -> n)
a.(i) <- i

这在语法上无效，因为它有 a letwith no in。您对问题的描述不够具体，无法判断这是否是您的问题。如果是这样，您需要in在第一行的右括号后添加。

如果这不是您的问题，您可能会注意到这里的第二行代码没有使用values，尽管这几乎是我期望它做的。目前的代码从标准输入读取一个值，然后忽略它读取的值。

如果这些都不是您的问题，您需要更仔细地描述您的问题。如果你只说“它没有用”，那就很难提供帮助。

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