class Program {
static void Main(string[] args) {
    byte[] byteArray = new byte[16];
    float value = float.Parse(Console.ReadLine());

    Console.Clear();
    Console.WriteLine("Value = {0}", value);
    GetBytes(byteArray, 1, value);
    Console.WriteLine("Byte Array = {0}", string.Join(" ", byteArray.Select(x => x.ToString("X")).ToArray()));

    float anotherValue;
    FromBytes(byteArray, 1, out anotherValue);
    Console.WriteLine("AnotherValue = {0}", anotherValue);

    anotherValue = BitConverter.ToSingle(byteArray, 1);
    Console.WriteLine("AnotherValue = {0}", anotherValue);

    Console.ReadKey();
}

//Maneira facil de entender
static unsafe byte[] ToByteArray(float value) {
    byte* valuePtr = (byte*)&value;
    byte[] result = new byte[sizeof(float)];
    for(int i = 0; i < result.Length; i++)
        result[i] = *valuePtr++;
    return result;
}

static unsafe float FromByteArray(byte[] arr) {
    float result;
    byte* resultPtr = (byte*)&result;
    for(int i = 0; i < sizeof(float); i++)
        *(resultPtr++) = arr[i];
    return result;
}

//Maneira mais avançada
static unsafe void GetBytes(byte[] array, uint offset, int value) {
    if(array == null)
        throw new ArgumentNullException("array");
    if(array.Length < offset + sizeof(int))
        throw new ArgumentOutOfRangeException("offset");

    fixed(byte* arrPtr = array)
        *((int*)(arrPtr + offset)) = value;
}

/*
static unsafe void GetBytes(byte[] array, uint offset, int value) {
    if(array == null)
        throw new ArgumentNullException("array");
    if(array.Length < offset + sizeof(int))
        throw new ArgumentOutOfRangeException("offset");

    fixed(byte* arrPtr = &array[offset]) {
        int* valPtr = (int*)arrPtr;
        *valPtr = value;
    }
}
    */

static unsafe void GetBytes(byte[] array, uint offset, float value) {
    GetBytes(array, offset, *(int*)&value);
}

static unsafe void FromBytes(byte[] array, uint offset, out int value) {
    if(array == null)
        throw new ArgumentNullException("array");
    if(array.Length < offset + sizeof(int))
        throw new ArgumentOutOfRangeException("offset");

    fixed(byte* arrPtr = array)
        value = *((int*)(arrPtr + offset));
}

static unsafe void FromBytes(byte[] array, uint offset, out float value) {
    if(array == null)
        throw new ArgumentNullException("array");
    if(array.Length < offset + sizeof(int))
        throw new ArgumentOutOfRangeException("offset");

    fixed (byte* arrPtr = array)
        value = *((float*)(arrPtr + offset));
}