# MemCpy(void*, void*, long)

> Copies a specified number of bytes from a source memory location to a destination memory location.

## Definition

* **Type:** Method
* **Namespace:** [Unity.Collections.LowLevel.Unsafe](/engine/6000.0/script-reference/unity/collections/lowlevel/unsafe.md)
* **Assembly:** UnityEngine.CoreModule

```csharp
public static void MemCpy(void* destination, void* source, long size)
```

### Parameters

**** (\[void\*]\(https\://learn.microsoft.com/dotnet/api/system.void)): A pointer to the destination memory block. Ensure this block is large enough to store the data being copied.**** (\[void\*]\(https\://learn.microsoft.com/dotnet/api/system.void)): A pointer to the source memory block. This block should contain the data you want to copy.**** (\[long]\(https\://learn.microsoft.com/dotnet/api/system.int64)): The number of bytes to copy from the source to the destination.

### Remarks

The `MemCpy` method efficiently copies data from one memory location to another. It is ideal for quickly duplicating memory content in performance-critical applications. Note that if the source and destination memory regions overlap, the result is not guaranteed to be correct. In such cases, use [UnsafeUtility.MemMove](/engine/6000.0/script-reference/unity/collections/lowlevel/unsafe/unsafeutility/memmove.md) to handle overlapping data safely.

```csharp
using UnityEngine;
using Unity.Collections.LowLevel.Unsafe;

public class MemCpyExample : MonoBehaviour
{
    void Start()
    {
        int numElements = 5;
        int size = numElements * sizeof(float);

        // Use stackalloc to allocate memory for source and destination buffers
        unsafe
        {
            float* srcBuffer = stackalloc float[numElements];
            float* dstBuffer = stackalloc float[numElements];

            // Initialize the source buffer with data
            for (int i = 0; i < numElements; i++)
            {
                srcBuffer[i] = i * 1.5f;  // Fills srcBuffer with values 0.0, 1.5, 3.0, 4.5, 6.0
            }

            // Use MemCpy to copy data from source to destination
            UnsafeUtility.MemCpy(dstBuffer, srcBuffer, size);

            // Output the contents of the destination buffer to verify the copy
            Debug.Log("Contents of destination buffer after MemCpy:");
            for (int i = 0; i < numElements; i++)
            {
                Debug.Log(dstBuffer[i]);  // Expected output: 0.0, 1.5, 3.0, 4.5, 6.0
            }
        }
    }
}
```

Additional Resources: [UnsafeUtility.MemMove](/engine/6000.0/script-reference/unity/collections/lowlevel/unsafe/unsafeutility/memmove.md).