在.NET string.format中强制对double执行正号

这是不寻常的,但是可以很容易地重写复杂类的toString方法。例如:

  class Complex {
    private double mReal, mImaginary;
    public Complex(double real, double imag) { mReal = real; mImaginary = imag; }
    private string WithSign(double value) {
      return value >= 0 ? "+" + value.ToString("N") : value.ToString("N");
    }
    public override string ToString() {
      return WithSign(mReal) + "i" + WithSign(mImaginary);
    }
  }

示例用法:

  static void Main(string[] args) {
    var c = new Complex(1, -1);
    Console.WriteLine(c.ToString());
    Console.ReadLine();
  }

输出:

  +1.00i-1.00

根据需要调整。

这可能离…

比如说:

String.Format("+{0:g}-{0:g}{1:g}-{1:g}j", real, imaginary)