C＃| Double.ToString()方法|套装– 1

Double.ToString()方法用于将当前实例的数值转换为其等效的字符串表示形式。此方法的重载列表中有4种方法，如下所示：

• ToString(String)方法
• ToString()方法
• ToString(IFormatProvider)方法
• ToString(String，IFormatProvider)方法

在这里，我们将讨论前两种方法。

ToString(String)方法

此方法用于使用指定格式将当前实例的数值转换为其等效的字符串表示形式。

Syntax: public string ToString (string format);
Here, it takes a numeric format string.

Return Value: This method returns the string representation of the value of the current instance as specified by format.

Exceptions: This method throws FormatException if format is invalid.

范例1：

// C# program to demonstrate the
// Double.ToString(String) Method
using System;
  
class GFG {
  
    // Main Method
    public static void Main()
    {
        try {
  
            // Declaring and initializing value
            double value = 16325.62d;
  
            // Declaring and initializing format
            string s = "E04";
  
            // using the method
            string str = value.ToString(s);
  
            // Display the value
            Console.WriteLine("String value is {0}", str);
        }
  
        catch (FormatException e) 
        {
            Console.WriteLine("Format is invalid.");
            Console.Write("Exception Thrown: ");
            Console.Write("{0}", e.GetType(), e.Message);
        }
    }
}

输出：

String value is 1.6326E+004

示例2：对于FormatException

// C# program to demonstrate the
// Double.ToString(String) Method
using System;
  
class GFG {
  
    // Main Method
    public static void Main()
    {
        try {
  
            // Declaring and initializing value
            double value = 16325.62d;
  
            // Declaring and initializing format
            string s = "a";
  
            // using the method
            string str = value.ToString(s);
  
            // Display the value
            Console.WriteLine("String value is {0}", str);
        }
  
        catch (FormatException e) 
        {
            Console.WriteLine("Format is invalid.");
            Console.Write("Exception Thrown: ");
            Console.Write("{0}", e.GetType(), e.Message);
        }
    }
}

输出：

Format is invalid.
Exception Thrown: System.FormatException

ToString()方法

此方法用于将当前实例的数值转换为其等效的字符串表示形式。

Syntax: public override string ToString ();

Return Value: This method returns a string which represents the value of this instance.

下面的程序说明Double.ToString()方法的用法：

范例1：

// C# program to demonstrate the
// Double.ToString()  Method
using System;
  
class GFG {
  
    // Main Method
    public static void Main()
    {
  
        // Declaring and initializing value
        double value = 7922816251426433759354.39503305d;
  
        // using ToString() method
        string round = value.ToString();
  
        // Display the value
        Console.WriteLine("String value is {0}", round);
    }
}

输出：

String value is 7.92281625142643E+21

范例2：

// C# program to demonstrate the
// Double.ToString() Method
using System;
using System.Globalization;
  
class GFG {
  
    // Main Method
    public static void Main()
    {
  
        // calling get() method
        get(20.3495d);
        get(30.5945994d);
        get(40d);
        get(4294967295.5858d);
    }
  
    // defining get() method
    public static void get(double value)
    {
  
        // using ToString() method
        string round = value.ToString();
  
        // Display the value
        Console.WriteLine("String value is {0}", round);
    }
}

输出：

String value is 20.3495
String value is 30.5945994
String value is 40
String value is 4294967295.5858

参考：

• https://docs.microsoft.com/zh-cn/dotnet/api/system.double.tostring?view=netframework-4.7.2