Go Language function Learning Tutorial _golang

This article describes the basic usage of the Go language function. Share to everyone for your reference, specific as follows:

Here's where the go function is different from some other languages.

1 function format is different

Copy Code code as follows:

Func getmsg (i int) (R string) {
Fmt. Println (i)
r = "HI"
Return r
}

Func shows that this is a function.

Getmsg is the name of the function

(i int) function receives an int parameter

(r string) function returns a string type return value

2 function can return multiple return values

This is not the same as c,php, it's the same as Lua.

Copy Code code as follows:

Func getmsg (i int) (R string, err string) {
Fmt. Println (i)
r = "HI"
Err = "No err"
Return R,err
}

3 Use of Defer

Defer means "call when function exits", especially when reading and writing files, you need to call the close operation after open, and use the close operation defer

Copy Code code as follows:

Func ReadFile (FilePath string) () {
File. Open (FilePath)
Defer file. Close ()
If True {
File. Read ()
} else {
return False
}
}

This is written in the file. Don't call close immediately after open, call file when return false. Close (). This effectively avoids the memory leak problem in the C language.

4 more difficult to understand: Panic,recover and defer

The role of defer is very clear in front of me.

Panic and recover, we look at them as throw and catch in other languages.

The following example:

Copy Code code as follows:

Package Main
Import "FMT"
Func Main () {
F ()
Fmt. PRINTLN ("returned normally from F.")
}
Func f () {
Defer func () {
If r: = Recover (); R!= Nil {
Fmt. Println ("Recovered in F", R)
}
}()
Fmt. Println ("calling G.")
G (0)
Fmt. PRINTLN ("returned normally from G.")
}
Func g (i int) {
If I > 3 {
Fmt. Println ("panicking!")
Panic (FMT. Sprintf ("%v", I))
}
Defer FMT. Println ("Defer in G", I)
Fmt. Println ("Printing in G", I)
G (i + 1)
}

Returned the following:

Copy Code code as follows:

Calling G.
Printing in G 0
Printing in G 1
Printing in G 2
Printing in G 3
panicking!
Defer in G 3
Defer in G 2
Defer in G 1
Defer in G 0
Recovered in F 4
Returned normally from F.

Panic throws out the message and jumps out of the function. Recover received the information and continued processing.

This example understands the basics of mastering recover and panic.

I hope this article will help you with your go language program.