c# - 务实地使用哪个字符来拆分字符串

Question

我有一个这样的字符串：“10+2”

         char[] a = new char[] { '+', '-' };     
         string[] un = txtdiscout.Text.ToString().Split(a);   
         string str1 = un[0];  //value show 10 
         string str2 = un[1];  //value show 2  

基本上，我可以清楚地看到并理解字符串是由 '+' 字符分割的。
有没有办法确定使用哪个字符来拆分字符串？

Answer 1

有几个字符串计算器 TDD 示例。这是我使用 NUnit 的简单案例。

    [TestFixture]
    public class TestHarnessLite
    {

    [TestCase("add", "5+10", ArithmeticOperation.Addition, 15.0d)]
    [TestCase("subtract", "5-10", ArithmeticOperation.Subtraction, -5.0d)]
    [TestCase("multiply", "5*10", ArithmeticOperation.Multiplication, 50.0d)]
    [TestCase("divide", "10/5", ArithmeticOperation.Division, 2.0d)]
    public void SomeTest(string scenario, string textInput, ArithmeticOperation expectedOperation, double expectedValue)
    {
        //arrange
        var math = new SimpleExpressionCalculator();

        //act
        var actual = math.Calculate(textInput);
        var actualOperator = math.Operation;

        //assert
        Assert.That(actualOperator, Is.EqualTo(expectedOperation));
        Assert.That(actual, Is.EqualTo(expectedValue), scenario);
    }

}

    public enum ArithmeticOperation
    {
        Unknown,
        Addition,
        Subtraction,
        Multiplication,
        Division
    }

public class SimpleExpressionCalculator
{
    public ArithmeticOperation Operation { get;set;}

    public double Calculate(string text)
    {
        var parsedValues = Parse(text);
        switch (parsedValues.Item2)
        {
            case "+":
                Operation = ArithmeticOperation.Addition;
                return parsedValues.Item1 + parsedValues.Item3;
            case "-":
                Operation = ArithmeticOperation.Subtraction;
                return parsedValues.Item1 - parsedValues.Item3;
            case "*":
                Operation = ArithmeticOperation.Multiplication;
                return parsedValues.Item1 * parsedValues.Item3;
            case "/":
                Operation = ArithmeticOperation.Division;
                if (parsedValues.Item3 == 0)
                    throw new DivideByZeroException("Can't divide by 0");
                return (parsedValues.Item1 *(1.0d)) / ((1.0d)*parsedValues.Item3);
        }
        return 0.0;
    }


    public Tuple<int,string,int> Parse(string input)
    {
        var groups = Regex.Matches(input, @"\d+|[+-/*]+");
        if (groups.Count != 3)
            throw new ArgumentException("invalid input");
        int operand1 = int.Parse(groups[0].Value);
        string oper = groups[1].Value.Trim();
        int operand2 = int.Parse(groups[2].Value);
        return new Tuple<int, string, int>(operand1, oper, operand2);
    }

}