C# 仅将用户输入限制为数字_C#_Validation

C# 仅将用户输入限制为数字

c# validation

C# 仅将用户输入限制为数字,c#,validation,C#,Validation,对C#[4小时新：）]来说是全新的，但希望在板脚计算器上有一些指针，将用户输入限制为仅数字，不允许字母或特殊字符首先，限制是否发生在类、方法和/或程序中？（我相信课程和方法）其次，我看到了下面的一个例子，我会使用类似的东西吗第三，如果是这样，我是否需要为KeyPress和KeyPressEventArgs创建单独的类？（我相信他们会自动到那里去。 publiccharkeychar{get；set；} private void textBox1_KeyPress(object sender

对C#[4小时新：）]来说是全新的，但希望在板脚计算器上有一些指针，将用户输入限制为仅数字，不允许字母或特殊字符

首先，限制是否发生在类、方法和/或程序中？（我相信课程和方法）

其次，我看到了下面的一个例子，我会使用类似的东西吗

第三，如果是这样，我是否需要为KeyPress和KeyPressEventArgs创建单独的类？（我相信他们会自动到那里去。

publiccharkeychar{get；set；}

private void textBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    // allows only letters
    if (!char.IsLetter(e.KeyChar))
    {
        e.Handled = true;
    }
}

我的节目

namespace BoardFt_MyTry_
{
    class Program
    {
        static void Main(string[] args)
        {
            Board board = new Board();

        board.lengthOfboard = Convert.ToDouble(askQuestion("What is the length of your board in inches?"));
        board.widthOfboard = Convert.ToDouble(askQuestion("What is the width of your board in inches?"));
        board.thicknessOfboard = Convert.ToDouble(askQuestion("What is the thickness of your board in inches?"));

        Console.WriteLine("Your board has {0} board feet.", board.CalcBoardFt());

        Console.ReadLine();
    }
    private static string askQuestion(string question)
    {
        Console.WriteLine(question);
        return Console.ReadLine();
    }

}

我的棋盘课

namespace BoardFt_MyTry_
{
    class Board
    {
        public double lengthOfboard;
        public double widthOfboard;
        public double thicknessOfboard;

    public double CalcBoardFt()
    {
        double boardft = 0;

        boardft = (this.lengthOfboard * this.widthOfboard * this.thicknessOfboard) / 144;

        return boardft;
    }
}
}

你不能在控制台应用程序中真正做到这一点。你所能做的就是允许用户输入坏数据，然后告诉用户数据坏了

您可以尝试以下方法：

class Program
{
    public double AskDnoubleQuestion(string message){
        do {
        Console.Write(message);
        var input = Console.ReadLine();

        if (String.IsNullOrEmpty(input)){
            Console.WriteLine("Input is required");
            continue;
         }
         double result;
         if (!double.TryParse(input, out result)){
           Console.WriteLine("Invalid input - must be a valid double");
           continue;
         }
         return result;
    }

    static void Main(string[] args)
    {
        Board board = new Board();

    board.lengthOfboard = AskDoubleQuestion("What is the length of your board in inches?");
    board.widthOfboard = AskDoubleQuestion(askQuestion("What is the width of your board in inches?");
    board.thicknessOfboard = AskDoubleQuestion(askQuestion("What is the thickness of your board in inches?");

    Console.WriteLine("Your board has {0} board feet.", board.CalcBoardFt());

    Console.ReadLine();
}

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Enter a number:");

        string number = ReadNumber();
        Console.WriteLine("You entered: " + number);
    }

    private static string ReadNumber()
    {
        string input = "";

        do
        {
            ConsoleKeyInfo keyInfo = Console.ReadKey(true);
            if (char.IsNumber(keyInfo.KeyChar))
            {
                input = input + keyInfo.KeyChar;
                Console.Write(keyInfo.KeyChar);
            }
            if (keyInfo.Key == ConsoleKey.Enter)
            {
                Console.WriteLine();
                break;
            }
            if (keyInfo.Key == ConsoleKey.Backspace)
            {
                input = input.Substring(0, input.Length - 1);
                Console.Write("\b \b");
            }
        } while (true);

        return input;
    }
}

string input = ReadOnlyNumbers();
Console.WriteLine(input);

你不能在控制台应用程序中真正做到这一点。你所能做的就是允许用户输入坏数据，然后告诉用户数据坏了

您可以尝试以下方法：

class Program
{
    public double AskDnoubleQuestion(string message){
        do {
        Console.Write(message);
        var input = Console.ReadLine();

        if (String.IsNullOrEmpty(input)){
            Console.WriteLine("Input is required");
            continue;
         }
         double result;
         if (!double.TryParse(input, out result)){
           Console.WriteLine("Invalid input - must be a valid double");
           continue;
         }
         return result;
    }

    static void Main(string[] args)
    {
        Board board = new Board();

    board.lengthOfboard = AskDoubleQuestion("What is the length of your board in inches?");
    board.widthOfboard = AskDoubleQuestion(askQuestion("What is the width of your board in inches?");
    board.thicknessOfboard = AskDoubleQuestion(askQuestion("What is the thickness of your board in inches?");

    Console.WriteLine("Your board has {0} board feet.", board.CalcBoardFt());

    Console.ReadLine();
}

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Enter a number:");

        string number = ReadNumber();
        Console.WriteLine("You entered: " + number);
    }

    private static string ReadNumber()
    {
        string input = "";

        do
        {
            ConsoleKeyInfo keyInfo = Console.ReadKey(true);
            if (char.IsNumber(keyInfo.KeyChar))
            {
                input = input + keyInfo.KeyChar;
                Console.Write(keyInfo.KeyChar);
            }
            if (keyInfo.Key == ConsoleKey.Enter)
            {
                Console.WriteLine();
                break;
            }
            if (keyInfo.Key == ConsoleKey.Backspace)
            {
                input = input.Substring(0, input.Length - 1);
                Console.Write("\b \b");
            }
        } while (true);

        return input;
    }
}

string input = ReadOnlyNumbers();
Console.WriteLine(input);

如果验证不是您想要的方式，您可以执行以下操作：

class Program
{
    public double AskDnoubleQuestion(string message){
        do {
        Console.Write(message);
        var input = Console.ReadLine();

        if (String.IsNullOrEmpty(input)){
            Console.WriteLine("Input is required");
            continue;
         }
         double result;
         if (!double.TryParse(input, out result)){
           Console.WriteLine("Invalid input - must be a valid double");
           continue;
         }
         return result;
    }

    static void Main(string[] args)
    {
        Board board = new Board();

    board.lengthOfboard = AskDoubleQuestion("What is the length of your board in inches?");
    board.widthOfboard = AskDoubleQuestion(askQuestion("What is the width of your board in inches?");
    board.thicknessOfboard = AskDoubleQuestion(askQuestion("What is the thickness of your board in inches?");

    Console.WriteLine("Your board has {0} board feet.", board.CalcBoardFt());

    Console.ReadLine();
}

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Enter a number:");

        string number = ReadNumber();
        Console.WriteLine("You entered: " + number);
    }

    private static string ReadNumber()
    {
        string input = "";

        do
        {
            ConsoleKeyInfo keyInfo = Console.ReadKey(true);
            if (char.IsNumber(keyInfo.KeyChar))
            {
                input = input + keyInfo.KeyChar;
                Console.Write(keyInfo.KeyChar);
            }
            if (keyInfo.Key == ConsoleKey.Enter)
            {
                Console.WriteLine();
                break;
            }
            if (keyInfo.Key == ConsoleKey.Backspace)
            {
                input = input.Substring(0, input.Length - 1);
                Console.Write("\b \b");
            }
        } while (true);

        return input;
    }
}

string input = ReadOnlyNumbers();
Console.WriteLine(input);

这将允许用户只输入数字。如果愿意，您可以按任何方式筛选它。例如，仅输入字母和数字等

目前，它只允许整数。如果要允许小数点，请将上面的行更改为：

If（char.IsNumber（keyInfo.KeyChar）| | keyInfo.KeyChar==”）

如果验证不是您想要进行的方式，您可以这样做：

class Program
{
    public double AskDnoubleQuestion(string message){
        do {
        Console.Write(message);
        var input = Console.ReadLine();

        if (String.IsNullOrEmpty(input)){
            Console.WriteLine("Input is required");
            continue;
         }
         double result;
         if (!double.TryParse(input, out result)){
           Console.WriteLine("Invalid input - must be a valid double");
           continue;
         }
         return result;
    }

    static void Main(string[] args)
    {
        Board board = new Board();

    board.lengthOfboard = AskDoubleQuestion("What is the length of your board in inches?");
    board.widthOfboard = AskDoubleQuestion(askQuestion("What is the width of your board in inches?");
    board.thicknessOfboard = AskDoubleQuestion(askQuestion("What is the thickness of your board in inches?");

    Console.WriteLine("Your board has {0} board feet.", board.CalcBoardFt());

    Console.ReadLine();
}

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Enter a number:");

        string number = ReadNumber();
        Console.WriteLine("You entered: " + number);
    }

    private static string ReadNumber()
    {
        string input = "";

        do
        {
            ConsoleKeyInfo keyInfo = Console.ReadKey(true);
            if (char.IsNumber(keyInfo.KeyChar))
            {
                input = input + keyInfo.KeyChar;
                Console.Write(keyInfo.KeyChar);
            }
            if (keyInfo.Key == ConsoleKey.Enter)
            {
                Console.WriteLine();
                break;
            }
            if (keyInfo.Key == ConsoleKey.Backspace)
            {
                input = input.Substring(0, input.Length - 1);
                Console.Write("\b \b");
            }
        } while (true);

        return input;
    }
}

string input = ReadOnlyNumbers();
Console.WriteLine(input);

这将允许用户只输入数字。如果愿意，您可以按任何方式筛选它。例如，仅输入字母和数字等

目前，它只允许整数。如果要允许小数点，请将上面的行更改为：

If（char.IsNumber（keyInfo.KeyChar）| | keyInfo.KeyChar==”）

您可以编写一个逐键读取的方法（不显示在控制台中），忽略非数字字符，打印有效字符并将其附加到

StringBuilder

实例，如下所示：

public static string ReadOnlyNumbers()
{
    StringBuilder input = new StringBuilder();
    ConsoleKeyInfo ckey;

    while ((ckey = Console.ReadKey(true)).Key != ConsoleKey.Enter)
    {
        if (Char.IsDigit(ckey.KeyChar))
        {
            Console.Write(ckey.KeyChar);
            input.Append(ckey.KeyChar);
        }

        if (ckey.Key == ConsoleKey.Backspace)
        {
            input.Length--;
            Console.Write("\b \b");
        }
    }

    Console.Write(Environment.NewLine);
    return input.ToString();
}

然后您可以这样使用它：

class Program
{
    public double AskDnoubleQuestion(string message){
        do {
        Console.Write(message);
        var input = Console.ReadLine();

        if (String.IsNullOrEmpty(input)){
            Console.WriteLine("Input is required");
            continue;
         }
         double result;
         if (!double.TryParse(input, out result)){
           Console.WriteLine("Invalid input - must be a valid double");
           continue;
         }
         return result;
    }

    static void Main(string[] args)
    {
        Board board = new Board();

    board.lengthOfboard = AskDoubleQuestion("What is the length of your board in inches?");
    board.widthOfboard = AskDoubleQuestion(askQuestion("What is the width of your board in inches?");
    board.thicknessOfboard = AskDoubleQuestion(askQuestion("What is the thickness of your board in inches?");

    Console.WriteLine("Your board has {0} board feet.", board.CalcBoardFt());

    Console.ReadLine();
}

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Enter a number:");

        string number = ReadNumber();
        Console.WriteLine("You entered: " + number);
    }

    private static string ReadNumber()
    {
        string input = "";

        do
        {
            ConsoleKeyInfo keyInfo = Console.ReadKey(true);
            if (char.IsNumber(keyInfo.KeyChar))
            {
                input = input + keyInfo.KeyChar;
                Console.Write(keyInfo.KeyChar);
            }
            if (keyInfo.Key == ConsoleKey.Enter)
            {
                Console.WriteLine();
                break;
            }
            if (keyInfo.Key == ConsoleKey.Backspace)
            {
                input = input.Substring(0, input.Length - 1);
                Console.Write("\b \b");
            }
        } while (true);

        return input;
    }
}

string input = ReadOnlyNumbers();
Console.WriteLine(input);

您可以编写一个方法，逐键读取（不显示在控制台中），忽略非数字字符，打印有效字符并将其附加到

StringBuilder

实例，如下所示：

public static string ReadOnlyNumbers()
{
    StringBuilder input = new StringBuilder();
    ConsoleKeyInfo ckey;

    while ((ckey = Console.ReadKey(true)).Key != ConsoleKey.Enter)
    {
        if (Char.IsDigit(ckey.KeyChar))
        {
            Console.Write(ckey.KeyChar);
            input.Append(ckey.KeyChar);
        }

        if (ckey.Key == ConsoleKey.Backspace)
        {
            input.Length--;
            Console.Write("\b \b");
        }
    }

    Console.Write(Environment.NewLine);
    return input.ToString();
}

然后您可以这样使用它：

class Program
{
    public double AskDnoubleQuestion(string message){
        do {
        Console.Write(message);
        var input = Console.ReadLine();

        if (String.IsNullOrEmpty(input)){
            Console.WriteLine("Input is required");
            continue;
         }
         double result;
         if (!double.TryParse(input, out result)){
           Console.WriteLine("Invalid input - must be a valid double");
           continue;
         }
         return result;
    }

    static void Main(string[] args)
    {
        Board board = new Board();

    board.lengthOfboard = AskDoubleQuestion("What is the length of your board in inches?");
    board.widthOfboard = AskDoubleQuestion(askQuestion("What is the width of your board in inches?");
    board.thicknessOfboard = AskDoubleQuestion(askQuestion("What is the thickness of your board in inches?");

    Console.WriteLine("Your board has {0} board feet.", board.CalcBoardFt());

    Console.ReadLine();
}

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Enter a number:");

        string number = ReadNumber();
        Console.WriteLine("You entered: " + number);
    }

    private static string ReadNumber()
    {
        string input = "";

        do
        {
            ConsoleKeyInfo keyInfo = Console.ReadKey(true);
            if (char.IsNumber(keyInfo.KeyChar))
            {
                input = input + keyInfo.KeyChar;
                Console.Write(keyInfo.KeyChar);
            }
            if (keyInfo.Key == ConsoleKey.Enter)
            {
                Console.WriteLine();
                break;
            }
            if (keyInfo.Key == ConsoleKey.Backspace)
            {
                input = input.Substring(0, input.Length - 1);
                Console.Write("\b \b");
            }
        } while (true);

        return input;
    }
}

string input = ReadOnlyNumbers();
Console.WriteLine(input);

这通常被称为“验证”。不要这样做-允许用户输入带有附加字符的数字，例如空格、逗号、+、-，然后根据验证结果过滤输入或拒绝输入。例如，+1000、-1000、1e3、0.1e+4可以，1j34不可以。感谢John澄清这两个是“验证”，以及确认我需要接受错误输入并通知用户它是错误的。（我会投票，但有1个声誉）。谢谢Danny，你也确认了同样的，允许用户输入，并返回一个错误以确认错误输入。这通常称为“验证”。不要这样做-允许用户输入带有附加字符的数字，例如空格、逗号、+、-，然后根据验证结果筛选输入或拒绝输入。例如，+1000、-1000、1e3、0.1e+4可以，1j34不可以。感谢John澄清这两个是“验证”，以及确认我需要接受错误输入并通知用户它是错误的。（我会投票，但有1个声誉）。谢谢Danny，你也确认了相同的，允许用户输入，并返回一个错误以确认错误输入。