Golang CopyN Function: Copy Bytes from Slice with Limit

The 'CopyN' function in Go is used to copy at most 'n' bytes from the source slice to the destination slice. It returns the number of bytes copied and an error if any.

The function signature is as follows:

func CopyN(dst []Type, src []Type, n int) int

Here, 'dst' is the destination slice, 'src' is the source slice, and 'n' is the maximum number of bytes to be copied.

Example:

package main

import (
    "fmt"
)

func main() {
    src := []byte('Hello, World!')
    dst := make([]byte, 5)

    n := CopyN(dst, src, 5)

    fmt.Println(string(dst)) // Output: Hello
    fmt.Println(n) // Output: 5
}

In this example, we have a source slice 'src' and a destination slice 'dst'. We want to copy at most 5 bytes from 'src' to 'dst'. We call the 'CopyN' function with 'dst', 'src', and 5 as arguments. The function returns the number of bytes copied, which is 5. We then print the contents of 'dst', which is 'Hello'.