Golang recursive access to directories and functions to modify array problems

This is a creation in Article, where the information may have evolved or changed.

I want to write a function like this:
Access all *.db files in a directory. And put in filepath[]. FilePath is a struct:

type filepath struct {    fullpath string   //文件路径名    filename string //文件名}

The finished program is this way, when printing:

package mainimport (    "io/ioutil"    "strings"    "path")const rootpath string = "D://testfile/2345"type filepath struct {    fullpath string    filename string}func main() {    var files []filepath    files = make([]filepath, 0, 1)    //dir,_:=ioutil.ReadDir(rootpath)    //递了个归    readdir(rootpath, files)    for _, v := range files {        println(v.filename, v.fullpath)    }}func readdir(dirs string, files []filepath) {    dir, _ := ioutil.ReadDir(dirs)    for _, v := range dir {        if v.IsDir() {            dir2 := path.Join(dirs, v.Name())            readdir(dir2, files)        } else {            if strings.HasSuffix(v.Name(), ".db") {                var str string = v.Name()                files = append(files, filepath{fullpath: path.Join(dirs, str), filename: str})            }        }    }}//输出：（什么~~都没有 一脸懵b.jpg）

A JB-style boy like me, a scripting language boy, has this kind of error when it doesn't use pointers. Add some information to debug?

//把最后一个else 里加两句，变成下面的：else {            if strings.HasSuffix(v.Name(), ".db") {                str  := v.Name()                println("老地址", files)                files = append(files, filepath{fullpath: path.Join(dirs, str), filename: str})                println("新地址", files)                //println(len(files) )            }//输出如下（一对一对看还是很方便  []里的数字含义为 [len/cap]）：老地址 [0/1]0xc042033f58新地址 [1/1]0xc042033f58老地址 [1/1]0xc042033f58新地址 [2/2]0xc042054b00老地址 [2/2]0xc042054b00新地址 [3/4]0xc042066b00老地址 [3/4]0xc042066b00新地址 [4/4]0xc042066b00老地址 [4/4]0xc042066b00新地址 [5/8]0xc042036300老地址 [5/8]0xc042036300新地址 [6/8]0xc042036300老地址 [6/8]0xc042036300新地址 [7/8]0xc042036300老地址 [7/8]0xc042036300新地址 [8/8]0xc042036300

Analysis, according to the urine of append, each time the memory is not enough to add Len space, will not generate a period of memory, reassigned to the pointer???
First confirm will not assign!!!!
It's a total of eight append.

1. Just one space, just right
2. There's not enough space, and Len is now 2.
3. Space is not enough, Len is now 4.
4. Enough
5. Not enough to add Len 8 of
6. Enough
7. Enough
8. Enough

The memory pointer has changed 3 times, so you can be sure that the first files = make ([]filepath, 0, 1) should have one set of data.
Then print the memory, println the position.

Func main () {var files []filepath files = make ([]filepath, 0, 1)//dir,_:=ioutil. ReadDir (RootPath)//handed a return to println ("old Address", files) ReadDir (RootPath, files) for _, V: = Range Files {print ln (v.filename, V.fullpath)}}func readdir (dirs string, files []filepath) {println ("new Address", files) dir, _: = Ioutil . ReadDir (dirs) for _, V: = range dir {if V.isdir () {dir2: = path. Join (dirs, V.name ()) Readdir (Dir2, files)} else {if strings. Hassuffix (V.name (), ". db") {str: = V.name () files = append (files, Filepath{fullpath:path. Join (dirs, str), filename:str})//println (Len (Files)}})}}//print information as follows: Old address [0/1]0xc042 033f58 new Address [0/1]0xc042033f58 new address [1/1]0xc042033f58 new address [1/1]0xc042033f58 new address [1/1]0xc042033f58 new address [1/1]0xc042033f58 new address [ 1/1]0xc042033f58 new Address [1/1]0xc042033f58 new address [1/1]0xc042033f58 new address [1/1]0xc042033f58 new address [1/1]0xc042033f58 new address [1/1] 0xc042033f58 new Address [1/1]0xc042033f58 new Address [1/1]0xc042033f58 new address [1/1]0xc042033f58 new address [1/1]0xc042033f58 new address [1/1]0xc042033f58 new address [1/1] 0xc042033f58 new Address [1/1]0xc042033f58 new address [1/1]0xc042033f58 new address [1/1]0xc042033f58 new address [1/1]0xc042033f58 new address [1/1] 0xc042033f58 new Address [1/1]0xc042033f58 new address [1/1]0xc042033f58

I found that the head pointer is still the head pointer, so the conclusion:
As the append increases, the head pointer is still the head pointer
Then the question comes, why is not print out!!!
Is there a hole in the Append and nothing to add?
Write a small program and try it.

package mainfunc main() {    var  p1 []int=[]int{1,2,3,4,5}    change(p1)    println(p1[5])}func change(p1 []int) {    p1=append(p1,2222)}//输出panic :数组越界

At this point, I really was ....
I suddenly think of something!!!!
Suddenly understood, P1 is a slice, and the P1 in main always points to {1,2,3,4,5} without pointing to {1,2,3,4,5,2222}.
The program is modified as follows:

package mainfunc main() {    var  p1 []int=[]int{1,2,3,4,5}    change2(&p1)    println(p1[5])}func change2(p1 *[]int) {    *p1=append(*p1,2222)}//输出： 2222

Here, I have another thought of the near perfect debugging information, is this paragraph:

Analysis, according to the urine of append, each time the memory is not enough to add Len space, will not generate a period of memory, reassigned to the pointer???
First confirm will not assign!!!!
It's a total of eight append.

1. Just one space, just right
2. There's not enough space, and Len is now 2.
3. Space is not enough, Len is now 4.
4. Enough
5. Not enough to add Len 8 of
6. Enough
7. Enough
8. Enough

I guess the 99.9% is probably 一个文件夹中有8个.db文件 I went to see it, really.
I think of two solutions:

1. Change the pointer (to TMD) like the above function
2. Returns a new slice

Finally I choose 2, others seem to be convenient point, so the whole program becomes:

package mainimport (    "io/ioutil"    "strings"    "path")const rootpath string = "D://testfile/2345"type filepath struct {    fullpath string    filename string}func main() {    var files []filepath    files = make([]filepath, 0, 1)     files= readdir(rootpath, files)    for _, v := range files {        println(v.filename, v.fullpath)    }}func readdir(dirs string, files []filepath) []filepath {    dir, _ := ioutil.ReadDir(dirs)    for _, v := range dir {        if v.IsDir() {            dir2 := path.Join(dirs, v.Name())             files=readdir(dir2, files)        } else {            if strings.HasSuffix(v.Name(), ".db") {                str  := v.Name()                files = append(files, filepath{fullpath: path.Join(dirs, str), filename: str})                //println(len(files) )            }        }    }    return files}

Again go Path bar, feel a little bit, and do not go.getpath this function, can only manually record the file path.
Alas, the program is finished, if I write a question, I hope you correct.