Preferred way to check for an empty string?

Mark Summerfield

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Jul 12, 2011, 6:54:58 AM7/12/11

to golang-nuts

Hi,

There are two obvious ways to check for an empty string:

if s == "" { ... }
if len(s) == 0 { ... }

I like the first one since it seems slightly more obvious.

Is there a preferred form?

Thanks!

--
Mark Summerfield, Qtrac Ltd, www.qtrac.eu
C++, Python, Qt, PyQt - training and consultancy
"Programming in Python 3" - ISBN 0321680561
http://www.qtrac.eu/py3book.html

Jan Mercl

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Jul 12, 2011, 7:12:21 AM7/12/11

to golan...@googlegroups.com

On Tuesday, July 12, 2011 12:54:58 PM UTC+2, Mark wrote:

There are two obvious ways to check for an empty string:
if s == "" { ... }
if len(s) == 0 { ... }
I like the first one since it seems slightly more obvious.
Is there a preferred form?

It's up to your preferences. Generated code for f() and g() is the same:

$ cat main.go

package main

func f(s string) {

if s == "" {

println("f")

}

func g(s string) {

if len(s) == 0 {

println("f")

}

func main() {

s := "abc"

f(s)

g(s)

}

$ 6g -S main.go

--- prog list "f" ---

0000 (main.go:3) TEXT f+0(SB),$16-16

0001 (main.go:4) JMP ,3

0002 (main.go:4) JMP ,13

0003 (main.go:4) MOVL s+8(FP),BX

0004 (main.go:4) CMPL BX,$0

0005 (main.go:4) JNE ,2

0006 (main.go:5) LEAQ go.string."f"+0(SB),SI

0007 (main.go:5) LEAQ (SP),DI

0008 (main.go:5) MOVSQ ,

0009 (main.go:5) MOVSQ ,

0010 (main.go:5) CALL ,runtime.printstring+0(SB)

0011 (main.go:5) CALL ,runtime.printnl+0(SB)

0012 (main.go:4) JMP ,13

0013 (main.go:7) RET ,

--- prog list "g" ---

0014 (main.go:9) TEXT g+0(SB),$16-16

0015 (main.go:10) JMP ,17

0016 (main.go:10) JMP ,27

0017 (main.go:10) MOVL s+8(FP),BX

0018 (main.go:10) CMPL BX,$0

0019 (main.go:10) JNE ,16

0020 (main.go:11) LEAQ go.string."f"+0(SB),SI

0021 (main.go:11) LEAQ (SP),DI

0022 (main.go:11) MOVSQ ,

0023 (main.go:11) MOVSQ ,

0024 (main.go:11) CALL ,runtime.printstring+0(SB)

0025 (main.go:11) CALL ,runtime.printnl+0(SB)

0026 (main.go:10) JMP ,27

0027 (main.go:13) RET ,

--- prog list "main" ---

...

$

yy

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Jul 12, 2011, 7:12:47 AM7/12/11

to Mark Summerfield, golang-nuts

2011/7/12 Mark Summerfield <li...@qtrac.plus.com>:

> Hi,
>
> There are two obvious ways to check for an empty string:
>
> if s == "" { ... }
> if len(s) == 0 { ... }
>
> I like the first one since it seems slightly more obvious.
>
> Is there a preferred form?
>
> Thanks!
>

You already asked this same question one year ago:
http://groups.google.com/group/golang-nuts/browse_thread/thread/9d3478bec3c7c68d/998bb93f806bf052

I thought we had agreed s + "badgerbadgerbadger" ==
"badgerbadgerbadger" was the preferred way.

--
- yiyus || JGL .