C# console.write 显示语句

Question

这是我的代码的一部分，我正在尝试让 console.write 仅显示 "Please re-enter number greater than 20 : " 的新语句。

问题是当我运行我的代码显示 "Please re-enter number greater than 20 : " 以及之前的语句 ("Enter amount of fuel used in litres : ")。在一行中。

如何让它不显示第一个写入语句？？

static double InputFuel()
    {
        double fFuel;
        string text;
        bool badValue = true;
        do
        {
            Console.Write("Enter amount of fuel used in litres : ");
            text = Console.ReadLine();
            if (double.TryParse(text, out fFuel) && fFuel >= 20)
            {
                badValue = false;
            }
            else
            {
                Console.WriteLine("\n\t {0} is below the minimum value of 20  \n\n", text);
                Console.Write("Please re-enter number greater than 20 : ");
            }
        } while (badValue);
        return fFuel;
    }//end InputTemp

Answer 1

您可以使用 Console.Clear() 清除控制台的当前内容。 https://msdn.microsoft.com/en-us/library/system.console.clear(v=vs.110).aspx

例如

static double InputFuel()
{
    double fFuel;
    string text;
    bool badValue = true;
    do
    {
        Console.Write("Enter amount of fuel used in litres : ");
        text = Console.ReadLine();
        if (double.TryParse(text, out fFuel) && fFuel >= 20)
        {
            badValue = false;
        }
        else
        {
            Console.Clear();
            Console.WriteLine("\n\t {0} is below the minimum value of 20  \n\n", text);
            Console.Write("Please re-enter number greater than 20 : ");
        }
    } while (badValue);
    return fFuel;
}

Answer 2

将行 Console.Write("Enter amount of fuel used in litres : "); 移到 while 循环之外。在您的示例中，它位于 while 循环内，因此每次输入不正确的答案时都会重复。如果你把它移到循环前面，它只会被写入控制台一次。

...
bool badValue = true;
Console.Write("Enter amount of fuel used in litres : ");
do
{
    text = Console.ReadLine();
    ...

Answer 3

我建议将循环更改为无限一个；如果问题应该只 陈述一次 将其从循环中拉出来：

    Console.Write("Enter amount of fuel used in litres : ");

    while (true) {
        text = Console.ReadLine();

        if (!double.TryParse(text, out fFuel)) 
            Console.Write("Please re-enter number in correct format: ");
        else if (fFuel <= 0)
            Console.Write("Please re-enter number greater than 0 : "); 
        else if (fFuel >= 20)
            Console.Write("Please re-enter number less than 20 : ");
        else
            break;            
    }

Answer 4

static double InputFuel()
    {
        double fFuel;
        string text;
        bool badValue = true;
        bool notFirst = false;
        do
        {
            if(!notFirst)
                Console.Write("Enter amount of fuel used in litres : ");
            notFirst = true;
            text = Console.ReadLine();
            if (double.TryParse(text, out fFuel) && fFuel >= 20)
            {
                badValue = false;
            }
            else
            {
                Console.WriteLine("\n\t {0} is below the minimum value of 20  \n\n", text);
                Console.Write("Please re-enter number greater than 20 : ");
            }
        } while (badValue);
        return fFuel;
    }

Answer 5

如果我没理解错的话，你的问题只是一个算法问题:

static double InputFuel()
    {
        double fFuel;
        string text;
        bool badValue = true;
        Console.Write("Enter amount of fuel used in litres : ");
        do
        {
            text = Console.ReadLine();
            if (double.TryParse(text, out fFuel) && fFuel >= 20)
            {
                badValue = false;
            }
            else
            {
                Console.Clear();
                Console.WriteLine("\n\t {0} is below the minimum value of 20  \n\n", text);
                Console.Write("Please re-enter number greater than 20 : ");
            }
        } while (badValue);
        return fFuel;
    }//end InputTemp

把第一次写出循环，只显示第一次，以后不会再来了。如果你想让它完全消失，只要在else语句中加一个Console.Clear();，把之前显示的东西擦掉，就搞定了。

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