indeed sprintfk. Also the trigger for puts needs to change as well as being non-zero each time you want it to print.
Is this what you're after?

instr 1
kindx init 1
kstep init 1
loop:

Sslot sprintfk "sq-%d", kstep
puts Sslot,kindx

kstep = kstep + 1
loop_lt kindx, 1, 32, loop

turnoff
endin

> Date: Wed, 22 Jun 2011 12:00:25 +0100
> From: rorywalsh@ear.ie
> To: csound@lists.bath.ac.uk
> Subject: Re: [Csnd] concat a value to a string and print it

>
> sprintfk?
>
> On 22 June 2011 10:52, stephane boussuge <stfboussuge@gmail.com> wrote:
> > hi list,
> > i'm trying to print a kvalue concat to a string but i'can't.
> > here's my code, what wrong ?
> > thank you in advance
> > stf
> >
> > <CsoundSynthesizer>
> >
> > <CsOptions>
> >
> > </CsOptions>
> >
> > <CsInstruments>
> >
> > instr 1
> >
> > kindx init 1
> >
> > kstep init 1
> >
> > loop:
> >
> > if kstep < 32 kgoto readval
> >
> > kgoto stop
> >
> > readval:
> >
> > Sslot sprintf "sq1-%i",kstep
> >
> > ;kstepval invalue Sslot
> >
> > puts Sslot,1
> >
> > kstep = kstep + 1
> >
> > loop_lt kindx, 1, 32, loop
> >
> > stop:
> >
> > turnoff
> >
> > endin
> >
> > </CsInstruments>
> >
> > <CsScore>
> >
> > i1 0 2
> >
> > e
> >
> > </CsScore>
> >
> > </CsoundSynthesizer>
>
>
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