Swift字符串任务[重复]

Question

我有一系列方程：

let tasks = ["11 + 14 = 25", "2 + 2 = 5"]

和功能

func checkTask(task: String) throws -> String 

应该：

1. 如果等式正确，则返回“Ok”，否则返回“正确答案：..”
2. 如果字符串不是方程式，则抛出错误，描述为“这不是方程式”

等式左边有两个数字，右边有一个数字。运算：加法和减法。

我该怎么做？

Answer 1

这是一个快速实现：它处理具有 2 个整数值和一个运算符的表达式，其中运算符为 +、-、* 或 /。表达式看起来像<value> <operator> <value> = <value>。表达式左侧的值是整数，但右侧的值可以是浮点值。 （例如try? checkTask(task: "7 / 2 = 3.5") 将打印OK）

如果您想做更高级的事情，我认为这可能是一个很好的起点。

enum Error: Swift.Error {
    case malformed
}
func checkTask(task: String) throws -> String {
    let operations = "*/+-"
    let split = task.replacingOccurrences(of: " ", with: "").split(separator: "=")
    guard let resultString = split.last,
          let expressionString = split.first else {
        throw Error.malformed
    }
    let expression = expressionString.split { character in
        operations.contains(character)
    }
    
    guard let operationString = expressionString.first(where: { operation in operations.contains(operation) }),
          let lhsString = expression.first,
          let rhsString = expression.last,
          let equationResult = Double(String(resultString)),
          let lhs = Double(lhsString),
          let rhs = Double(rhsString) else {
        throw Error.malformed
    }
    
    var operation: (Double, Double) -> Double
    switch operationString {
    case "+":
        operation = (+)
    case "-":
        operation = (-)
    case "*":
        operation = (*)
    case "/":
        operation = (/)
    default:
        throw Error.malformed
    }
    let result = operation(lhs, rhs)
    guard result == equationResult else {
        return "Correct answer: \(result)"
    }
    return "OK"
}
let tasks = ["11 + 14 = 25", "2 + 2 = 5"]
let first = try? checkTask(task: tasks.first!) // "OK"
let second = try? checkTask(task: tasks.last!) // "Correct answer: 4.0"

如果您想要描述错误，您必须自己进行修改。