The "Advanced Bash-Scripting Guide" has a section on string manipulation
that's useful. I can find the equivalent of most of the BASIC string
functions that I used a quarter of a century ago.

I've now figured out (with a little help from this group) that the Bash
equivalent of the BASIC CHR$() function for converting a decimal number
into its ASCII character is:

$(printf "\\$(printf "%03o" $x)")

Can Bash go the other way - from a character to its ASCII decimal number
- like the BASIC ASC() function?

--
Dave Farrance

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Dave Farrance wrote:
> The "Advanced Bash-Scripting Guide" has a section on string manipulation
> that's useful. I can find the equivalent of most of the BASIC string
> functions that I used a quarter of a century ago.
>
> I've now figured out (with a little help from this group) that the Bash
> equivalent of the BASIC CHR$() function for converting a decimal number
> into its ASCII character is:
>
>    $(printf "\\$(printf "%03o" $x)")
>
> Can Bash go the other way - from a character to its ASCII decimal number
> - like the BASIC ASC() function?
>

A solution with bash:

-------------------------begin-----------------------------
#!/bin/bash

ord()
{
if [[ $1 ]]
then
echo "$(od -td1 <<<"$1" | awk 'NR==1{print $2}')"
else
exit 1
fi
}

for i
do
for ((j=0; j < ${#i}; ++j))
do
ch=${i:$j:1}
dec=$(ord "$ch")
echo -e "char: '$ch'\t ord: $dec"
done
done
------------------------end--------------------------------


better use perl:

ch=0; PERL -e "print ord($ch),  \"\n\";"


Regards

Steffen Schuler

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Steffen Schuler wrote:
> Dave Farrance wrote:
> 
>
>
> A solution with bash:
>
> -------------------------begin-----------------------------
> #!/bin/bash
>
> ord()
> {
>   if [[ $1 ]]
>   then
>      echo "$(od -td1 <<<"$1" | awk 'NR==1{print $2}')"
>   else
>     exit 1
>   fi
> }
>
> for i
> do
>   for ((j=0; j < ${#i}; ++j))
>   do
>     ch=${i:$j:1}
>     dec=$(ord "$ch")
>     echo -e "char: '$ch'\t ord: $dec"
>   done
> done
> ------------------------end--------------------------------
>
>
> better use perl:
>
> ch=0; PERL -e "print ord($ch),  \"\n\";"
>
>
> Regards
>
> Steffen Schuler
the echo in the bash ord() function is superfluous.

Regards

Steffen Schuler

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Steffen Schuler <schuler.steffenDELETETHIS@gmx.de> wrote:

>Dave Farrance wrote: 
[vbcol=seagreen]
> ...
> echo "$(od -td1 <<<"$1" | awk 'NR==1{print $2}')"
> ...
> ch=0; PERL -e "print ord($ch),  \"\n\";"

Thanks. Looks like there's no way with bash builtins.

BTW, quotes are needed in that PERL function when called from bash.

$ ch=m; PERL -e "print ord($ch),  \"\n\";"
Search pattern not terminated at -e line 1.
$ ch=m; PERL -e "print ord('$ch'),  \"\n\";"
109
_
--
Dave Farrance

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Dave Farrance wrote:
> Steffen Schuler <schuler.steffenDELETETHIS@gmx.de> wrote:
>
> 
>
> 
>
>
> Thanks. Looks like there's no way with bash builtins.
>
> BTW, quotes are needed in that PERL function when called from bash.
>
> $ ch=m; PERL -e "print ord($ch),  \"\n\";"
> Search pattern not terminated at -e line 1.
> $ ch=m; PERL -e "print ord('$ch'),  \"\n\";"
> 109
>

A solution with only bash builtins with demo:


#!/bin/bash

char()
{
printf \\$(printf "%03o" "$1")
}

asc()
{
local i
for ((i=1; i<256; ++i))
do
if [ "$(char "$i")" = "$1" ]
then
echo "$i"
break
fi
done
return 1
}

for ((i=32; i<127; ++i))
do
ch=$(char "$i")
printf "ASC('%s') = % 3d\n" "$ch" "$(asc "$ch")"
done

Regards

Steffen Schuler

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Steffen Schuler wrote:
> Steffen Schuler wrote:
> 
>
>
> replace the 'break' in asc() by 'return 0'

A significantly faster pure bash script based on binary search:

---------------------------begin--------------------------
#!/bin/bash

char()
{
printf \\$(printf "%03o" "$1")
}

asc()
{
local ch="$1"
local low hi mid ch_mid
low=1
hi=255
while ((low+1<hi))
do
((mid=(low+hi)/2))
ch_mid=$(char "$mid")
if [[ "$ch_mid" < "$ch" ]]
then
low="$mid"
elif [[ "$ch_mid" > "$ch" ]]
then
hi="$mid"
else
echo "$mid"
return 0
fi
done
return 1
}

for ((i=32; i<127; ++i))
do
ch=$(char "$i")
printf "ASC('%s') = %3d\n" "$ch" "$(asc "$ch")"
done
------------------------end------------------------------

Regards

Steffen Schuler

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Dave Farrance wrote:
> Steffen Schuler <schuler.steffenDELETETHIS@gmx.de> wrote:
> 
> 
>
> Thanks. Looks like there's no way with bash builtins.
>
> BTW, quotes are needed in that PERL function when called from bash.
>
> $ ch=m; PERL -e "print ord($ch),  \"\n\";"
> Search pattern not terminated at -e line 1.
> $ ch=m; PERL -e "print ord('$ch'),  \"\n\";"
> 109

Or more simply:

$ ch=m; PERL -le "print ord'$ch'"
109

And the other way:

$ ch=109; PERL -le "print chr'$ch'"
m



John
--
use Perl;
program
fulfillment

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On 16.07.2006, John W. Krahn <someone@example.com> wrote:
> Dave Farrance wrote: 
>
> Or more simply:
>
> $ ch=m; PERL -le "print ord'$ch'"
> 109
>
> And the other way:
>
> $ ch=109; PERL -le "print chr'$ch'"
> m

OMG! What the hell are you doing to Perl? It hurts!

#v+
ch=m PERL -le 'print ord $ENV{ch}'
perl -le 'print ord shift' m
#v-

--
Stanislaw Klekot

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Dave Farrance <DaveFarrance@omitthisyahooandthis.co.uk> wrote:
> The "Advanced Bash-Scripting Guide" has a section on string manipulation
> that's useful. I can find the equivalent of most of the BASIC string
> functions that I used a quarter of a century ago.
>
> I've now figured out (with a little help from this group) that the Bash
> equivalent of the BASIC CHR$() function for converting a decimal number
> into its ASCII character is:
>
>    $(printf "\\$(printf "%03o" $x)")
>
> Can Bash go the other way - from a character to its ASCII decimal number
> - like the BASIC ASC() function?

http://home.eol.ca/~parkw/index.html#ctype.h

--
William Park <opengeometry@yahoo.ca>, Toronto, Canada
ThinFlash: Linux thin-client on USB key (flash) drive
http://home.eol.ca/~parkw/thinflash.html
BashDiff: Super Bash shell
http://freshmeat.net/projects/bashdiff/

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On 2006-07-16, Dave Farrance wrote:
> The "Advanced Bash-Scripting Guide" has a section on string manipulation
> that's useful. I can find the equivalent of most of the BASIC string
> functions that I used a quarter of a century ago.
>
> I've now figured out (with a little help from this group) that the Bash
> equivalent of the BASIC CHR$() function for converting a decimal number
> into its ASCII character is:
>
>    $(printf "\\$(printf "%03o" $x)")
>
> Can Bash go the other way - from a character to its ASCII decimal number
> - like the BASIC ASC() function?

From the SUS printf  spec:

* If the leading character is a single-quote or double-quote, the
value shall be the numeric value in the underlying codeset of
the character following the single-quote or double-quote.

E.g.:

CHAR=A
printf "%d\n" "'$CHAR"


--
Chris F.A. Johnson, author              <http://cfaj.freeshell.org>
Shell Scripting Recipes: A Problem-Solution Approach (2005, Apress)
===== My code in this post, if any, assumes the POSIX locale
===== and is released under the GNU General Public Licence

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