C# | Convert.ToDouble(String, IFormatProvider) Method

This method is used to converts the specified string representation of a number to an equivalent double-precision floating-point number, using the specified culture-specific formatting information.

Syntax:

public static double ToDouble (string value, IFormatProvider provider);

Parameters:

• value: It is a string that contains the number to convert.
• provider: It is an object that supplies culture-specific formatting information.

Return Value: This method returns a double-precision floating-point number which is equivalent to the number in value, or 0 (zero) if value is null.

Exceptions:

• FormatException: If the value is not a number in a valid format.
• OverflowException: If the value represents a number that is less than MinValue or greater than MaxValue.

Below programs illustrate the use of Convert.ToDouble(String, IFormatProvider) Method:

Example 1:

// C# program to demonstrate the
// Convert.ToDouble() Method
using System;
using System.Globalization;

class GFG {

// Main Method
public static void Main()
{
    try {

        // Create a NumberFormatInfo object
        // and set some of its properties.
        NumberFormatInfo provider = new NumberFormatInfo();
        provider.NumberDecimalSeparator = ", ";
        provider.NumberGroupSeparator = ".";
        provider.NumberGroupSizes = new int[] { 3 };

        // declaring and initializing String array
        string[] values = {"123456789", "12345.6789",
                                      "12345, 6789"};

        // calling get() Method
        Console.Write("Converted decimal value "
                         + "of specified strings: ");

        for (int j = 0; j < values.Length; j++)
        {
            get(values[j], provider);
        }
    }

    catch (FormatException e)
    {

        Console.WriteLine("\n");
        Console.Write("Exception Thrown: ");
        Console.Write("{0}", e.GetType(), e.Message);
    }

    catch (OverflowException e)
    {

        Console.WriteLine("\n");
        Console.Write("Exception Thrown: ");
        Console.Write("{0}", e.GetType(), e.Message);
    }
}

// Defining get() method
public static void get(string s,
      NumberFormatInfo provider)
{

    // converting string to specified char
    double val = Convert.ToDouble(s, provider);

    // display the converted char value
    Console.Write(" {0}, ", val);
}
}

Output:

Converted decimal value of specified strings:  123456789,  123456789,  12345.6789,

Example 2: For FormatException

// C# program to demonstrate the
// Convert.ToDouble() Method
using System;
using System.Globalization;

class GFG {

// Main Method
public static void Main()
{
    try {

        // Create a NumberFormatInfo object
        // and set some of its properties.
        NumberFormatInfo provider = new NumberFormatInfo();
        provider.NumberDecimalSeparator = ", ";
        provider.NumberGroupSeparator = ".";
        provider.NumberGroupSizes = new int[] { 3 };

        // declaring and initializing String array
        string[] values = {"123456789", "12345.6789",
                                      "12345, 6789"};

        // calling get() Method
        Console.Write("Converted double value"
                 + " of specified strings: ");

        for (int j = 0; j < values.Length; j++)
        {

            get(values[j], provider);
        }

        Console.WriteLine("\n");
        string s = "123 456, 789";

        Console.WriteLine("format of s is invalid ");

        // converting string to specified char
        double val = Convert.ToDouble(s, provider);

        // display the converted char value
        Console.Write(" {0}, ", val);
    }

    catch (FormatException e)
    {

        Console.Write("Exception Thrown: ");
        Console.Write("{0}", e.GetType(), e.Message);
    }

    catch (OverflowException e)
    {

        Console.Write("Exception Thrown: ");
        Console.Write("{0}", e.GetType(), e.Message);
    }
}

// Defining get() method
public static void get(string s,
      NumberFormatInfo provider)
{

    // converting string to specified char
    double val = Convert.ToDouble(s, provider);

    // display the converted char value
    Console.Write(" {0}, ", val);
}
}

Output:

Converted double value of specified strings:  123456789,  123456789,  12345.6789, 

format of s is invalid 
Exception Thrown: System.FormatException

Example 3: For OverflowException

// C# program to demonstrate the
// Convert.ToDouble() Method
using System;
using System.Globalization;

class GFG {

// Main Method
public static void Main()
{
    try {

        // Create a NumberFormatInfo object
        // and set some of its properties.
        NumberFormatInfo provider = new NumberFormatInfo();
        provider.NumberDecimalSeparator = ", ";
        provider.NumberGroupSeparator = ".";
        provider.NumberGroupSizes = new int[] { 3 };

        // declaring and initializing String array
        string[] values = { "123456789", "12345.6789",
                                      "12345, 6789" };

        // calling get() Method
        Console.Write("Converted decimal value "
                    + "of specified strings: ");

        for (int j = 0; j < values.Length; j++)
        {

            get(values[j], provider);
        }

        Console.WriteLine("\n");
        string s = "-7922816251426433759354395033500000";

        Console.WriteLine("s is less than the MaxValue");

        // converting string to specified char
        decimal val = Convert.ToDecimal(s, provider);

        // display the converted char value
        Console.Write(" {0}, ", val);
    }

    catch (FormatException e)
    {
        Console.Write("Exception Thrown: ");
        Console.Write("{0}", e.GetType(), e.Message);
    }

    catch (OverflowException e)
    {
        Console.Write("Exception Thrown: ");
        Console.Write("{0}", e.GetType(), e.Message);
    }
}

// Defining get() method
public static void get(string s,
      NumberFormatInfo provider)
{

    // converting string to specified char
    double val = Convert.ToDouble(s, provider);

    // display the converted char value
    Console.Write(" {0}, ", val);
}
}

Output:

Converted decimal value of specified strings:  123456789,  123456789,  12345.6789, 

s is less than the MaxValue
Exception Thrown: System.OverflowException

Reference:

• https://docs.microsoft.com/en-us/dotnet/api/system.convert.todouble?view=netframework-4.7.2#System_Convert_ToDouble_System_String_System_IFormatProvider_