String not printing properly using FprintF

Question

I was trying my hand at an irc client but I can't get a string to "print" properly using Fprintf. This is the method that is not working:

func (irc *IrcConnection) sendMessage(message string, args ...interface{}) (error){

    fmt.Printf("Sending: "+message, args)
    _, err := fmt.Fprintf(irc.connection, message+" \r\n", args)
    if err != nil{
        return err;
    }

    return nil
}

An example of me calling it is

ircConnection.sendMessage("PASS %s",  ircConnection.info.password)

The output ends up being "PASS [password]", meaning that the password prints with square brackets instead of just the password.

I though at first it was the ...interface{} making it print like that but if I change it to ...string it has the same problem.

If I try:

var test interface{} = ircConnection.info.password
fmt.Printf("%s", test)

It prints without the brackets.

I'm pretty new to go and have no idea what to try next.

WinterDev · Accepted Answer · 2016-11-12 05:18:07Z

2

Ok, just figured it out

 _, err := fmt.Fprintf(irc.connection, message+" \r\n", args)

needs to become

 _, err := fmt.Fprintf(irc.connection, message+" \r\n", args...)

I was trying to print an array/slice

answered Nov 12, 2016 at 5:18

WinterDev

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Comments

hobbs · Accepted Answer · 2016-11-12 05:18:19Z

1

You want fmt.Fprintf(irc.connection, message+" \r\n", args...) — note the args..., not args. When your function declares args ...interface{} that means that it will get all of the remaining arguments as a slice. When you pass args to Fprintf, you're telling it to print that slice. As one thing, a slice. To flatten the slice back out into a list of arguments you use the ....

See Passing arguments to ... parameters.

answered Nov 12, 2016 at 5:18

hobbs

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