从文件读取时如何查找EOF

Question

I am using the following code to read a file in Go:

spoon , err := ioutil.ReadFile(os.Args[1])
if err!=nil {
        panic ("File reading error")
}

Now I check for every byte I pick for what character it is. For example:

spoon[i]==' ' //for checking space

Likewise I read the whole file (I know there maybe other ways of reading it) but keeping this way intact, how can I know that I have reached EOF of the file and I should stop reading it further?

Please don't suggest to find the length of spoon and start a loop. I want a sure shot way of finding EOF.

Answer 1

A slice has no concept of end of file. The slice returned by ioutil.ReadFile has a specific length, which reflects the size of the file it was read from. A common idiom, but only one of the possible used in this case, is to range the slice, effectively "consuming" all of the bytes, originally sitting in the file:

for i, b := range spoon {
        // At index 'i' is byte 'b'
        // At file's offset 'i', 'b' was read
        ... do something useful here
}