C# | BitConverter.DoubleToInt64Bits() Method

Last Updated : 11 Jul, 2025
BitConverter.DoubleToInt64Bits(Double) Method is used to convert the specified double-precision floating point number to a 64-bit signed integer. Syntax: 
public static long DoubleToInt64Bits (double value);
Here, the value is the number which is to be converted. Return Value: This method returns a 64-bit signed integer whose value is equivalent to value. Below programs illustrate the use of BitConverter.DoubleToInt64Bits(Double) Method: Example 1: CSHARP 
// C# program to demonstrate
// BitConverter.DoubleToInt64Bits()
// Method
using System;

public class GFG {

    // Main Method
    public static void Main()
    {

        // declaring and initializing double value
        double value = 1.2345678901234565;

        // Display the double value
        Console.Write("double-precision floating point: ");
        Console.WriteLine("{0}", value);
        Console.WriteLine();

        // Converting double to long value
        // using BitConverter.DoubleToInt64Bits()
        // Method
        long value1 = BitConverter.DoubleToInt64Bits(value);

        // Display the 64-bit signed integer.
        Console.Write("64-bit signed integer: ");
        Console.WriteLine("{0}", value1);
    }
}
Output: 
double-precision floating point: 1.23456789012346

64-bit signed integer: 4608238818662570490
Example 2: CSHARP 
// C# program to demonstrate
// BitConverter.DoubleToInt64Bits()
// Method
using System;

class GFG {

    // Main Method
    public static void Main()
    {

        // declaring and initializing double value
        double value = 1.0;

        // Display the double value
        Console.Write("double-precision floating point: ");
        Console.WriteLine("{0}", value);
        Console.WriteLine();

        // Converting double to long value
        // using BitConverter.DoubleToInt64Bits()
        // Method
        long value1 = BitConverter.DoubleToInt64Bits(value);

        // Display the 64-bit signed integer.
        Console.Write("64-bit signed integer: ");
        Console.WriteLine("{0}", value1);
        Console.WriteLine();

        // Display the Hexadecimal value
        Console.Write("Hexadecimal value: ");
        Console.WriteLine(value1.ToString("X"));
    }
}
Output: 
double-precision floating point: 1

64-bit signed integer: 4607182418800017408

Hexadecimal value: 3FF0000000000000
Reference:
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