C# Convert Int to Byte Array

How to Convert an Integer to a Byte Array in C#?

An integer (int) in C# is represented using 4 bytes (32 bits). It can store values ranging from -2,147,483,648 to 2,147,483,647.

These 4 bytes represent the integer in memory, and converting this representation into a byte array can be useful for various purposes, such as serialization or network communication.

For example, Using BitConverter.GetBytes()

C# provides the BitConverter.GetBytes() method to convert an integer into a byte array of size 4.

int number = 12345;
byte[] bytes = BitConverter.GetBytes(number);

One critical aspect to consider is the endianness of the output. Endianness determines the order in which bytes are arranged:

• Little-endian: The least significant byte comes first.

• Big-endian: The most significant byte comes first.

BitConverter.GetBytes() returns the byte array in the system's native endianness, which is typically little-endian on most modern systems. However, certain protocols and file formats (e.g., RFC1014 3.2) use big-endian as the standard.

If you need the byte array in big-endian format, you can reverse the output using Array.Reverse().

The following code ensures the byte array is always returned in big-endian format, regardless of the system's endianness:

int number = 12345;
byte[] bytes = BitConverter.GetBytes(number);
if (BitConverter.IsLittleEndian)
{
    Array.Reverse(bytes);
}

In this example:

• BitConverter.GetBytes(number) generates the byte array in the system's native endianness.

• BitConverter.IsLittleEndian checks if the system uses little-endian format.

• If the system is little-endian, Array.Reverse(bytes) reverses the byte array to convert it to big-endian.