Parse file based on byte parts

php editor Baicao introduces you to a method of parsing files based on byte parts. This method allows us to process large files without loading the entire file into memory at once, but instead parses the file contents step by step as needed. This method can not only reduce memory usage, but also improve the running efficiency of the program. The specific implementation method is that we can set up a buffer, read a certain number of bytes from the file into the buffer each time, and then gradually parse the content in the buffer until the file is parsed. This method can be applied to various file parsing scenarios, such as log file parsing, large data file parsing, etc.

Question content

I am parsing a file which is read byte by byte and I have instructions as to which byte represents which part of the file.

Order file:

1. The first 4 bytes are the version

2. The next 4 bytes are an integer indicating the expected order quantity.

3. For each order (starting from #2), the 4-byte integer is the order id.

To parse this, I first load the file:

file, err := os.Open("orders.abc")

version := make([]byte, 4)
c, err := file.Read(version)
fmt.Printf("read %d, version is %d", c, version)

orderCount := make([]byte, 4)
c2, err := file.Read(orderCount)
fmt.Printf("read %d, orderCount is %d", c2, orderCount)

for i := 0; i < orderCount_as_int; i++ {

  orderId := make([]byte, 4)
  c3, err := file.Read(orderId)     
}

Is there a more elegant way to parse such a file?

Also, how do I convert version/ordercount to an integer so I can use the value?

Workaround

You want to use encoding/binary.read instead of calling read directly. For example

var version int32
err := binary.Read(file, binary.LittleEndian, &version)

(You also need to know whether the data in the file is big-endian or little-endian, and choose the appropriate byte order). The binary package will do the decoding for you.

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