c# - 所有路径都不返回值

Question

我不确定我的代码到底有什么问题，因为它以前曾在工作，但现在它向我显示此错误。

main.cs(179,20): error CS0161: `CarProgram.ChangeGears(int, string)': not all code paths return a value

该程序是针对汽车功能的，就像某种程度上的模拟器一样，但是我想先解决第一个错误，然后再继续讨论其他问题。

这是代码

private static int ChangeGears(int s, string g)
{
     Console.WriteLine("Inside the function Change Gears");
     if (s == 0)
     {
      string haveGear;
     Console.WriteLine("What gear would you like to have?");
     haveGear = Console.ReadLine();
     haveGear = haveGear.ToUpper();
     if (haveGear == "P" || haveGear == "R" || haveGear == "N" || haveGear == "D")
        {
            switch (haveGear)
            {
                case "P":
                {
                    Console.WriteLine("You are in park");
                    break;
                }

                case "N":
                {
                    Console.WriteLine("You are in neutral");
                    break;
                }

                case "D":
                {
                    Console.WriteLine("You are in drive");
                    break;
                }

                case "R":
                {
                    Console.WriteLine("You are in reverse");
                    break;
                }
            }//close
            g = haveGear;
        }
     else
     {
         Console.WriteLine("The speed must be 0 to change gears.");
     }
     Console.WriteLine("Gear is "+ g);

     return 0;
}
}// close ChangeGears

Answer 1

请格式化您的例程，

private static int ChangeGears(int s, string g) {
  Console.WriteLine("Inside the function Change Gears");

  if (s == 0) {
    ...
    /* Some logic here */
    ... 
    return 0; // <- when s == 0 ChangeGears returns 0
  }

  //TODO: return value when s != 0
}// close ChangeGears

而且您清楚地看到ChangeGears时s != 0不返回任何内容