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Homework and Emergencies Homework & Coursework Questions Alphabetical help.
# 22  
Old 08-19-2011
No. Because of the absence of the priority of boolean operators in shell. You should use some kind of parenthesis:
Code:
for letter in A _ B o D 0 Z  ; do
  if [[ "$letter" < Z  || "$letter" == Z ]] && [[ "$letter" > A || "$letter" == A ]]; then
    echo "$letter" is in A..Z
  else
    echo "$letter" is not in A..Z
  fi
done

Ha! It doesn't work. Some kind of bash quirks - "o" is in A..Z. (and in ksh but not in zsh).
Ok. You can use
Code:
for letter in A _ B o D 0 Z  ; do                                            
  if echo {A..Z} | egrep -q " ?$letter ?"; then
    echo "$letter" is in A..Z
  else
    echo "$letter" is not in A..Z
  fi
done

Last edited by yazu; 08-19-2011 at 12:01 PM..
# 23  
Old 08-19-2011
sorry i fail to see where you used your parenthesis to make a comparison.

EDIT: If i think you did what i think you did then i probably did do it. If you check out the new code i made.

Code:
"3")
clear
echo Enter capitol alphabetical letters one at a time and press 0 to finish
letter="Z"
if [[ "$letter" < Z || "$letter" == Z ]] && [[ "$letter" > A || "$letter" == A ]
]; then
        while [[ "$letter" == Z || "$letter" < Z ]] && [[ "$letter" > A || "$let
ter" == A ]] && [[ "$letter" != 0 ]]; do
        read letter2
                if [[ $letter2 < $letter ]]; then
                letter=letter2
                else
                break
                fi
        break
        done
elif [ "$letter2" == 0 ]; then
echo Lowest letter is $letter
else
echo "Invalid input. Please enter A-Z (capital) one at a time finalised by a 0"
fi
;;

# 24  
Old 08-19-2011
Well. You code doesn't work. And it doesn't work in many places - from simple errors (like letter=letter2) to logic (assignment Z to letter, don't check for length of input, etc.)
I really don't know how to help you. Just several advises:
1. You should write you script at little pieces and test it after every change.
2. You should use the whole working script for changes, not a fragment.
3. You should write you attentions as pseudo-code in words.
4. You should break your problem to little ones and decide them separately.
If you have time maybe tomorrow I can help you. Today I'm out.
# 25  
Old 08-20-2011
Okay thanks for your help thus far. Ill sleep over it and see if i can make changes. Possibly ill start again and use case instead. Ill be on tomorrow.

---------- Post updated at 04:00 PM ---------- Previous update was at 12:19 AM ----------

Ive been working on the code and this is what i get so far. Everything works ok it accepts inputs one at a time. However when i want to exit (by pressing 0 and enter) i need to do it twice and it makes 0 the lowest letter. Its not what i want and im sure in the code i made it so it would exit out right after 0 was found and to display the lowest letter.

Code:
"3")
clear
echo Enter capitol alphabetical letters one at a time and press 0 to finish
letter="Z"
if [[ "$letter" < Z || "$letter" == Z ]] && [[ "$letter" > A || "$letter" == A ]] || [[ "$letter2" == 0 ]]; then
        while [[ "$letter" == Z || "$letter" < Z ]] && [[ "$letter" > A || "$letter" == A ]] || [[ "$letter2" == 0 ]]; do
        letter2="Z"
        read letter2
                if [[ "$letter2" < "$letter" ]]; then
                letter=$letter2
                elif [[ "$letter2" == 0 ]]; then
                echo Lowest Letter is $letter
                echo Press enter to continue...
                elif [[ "$letter2" == "$letter" ]]; then
                letter=$letter2
                elif [[ "$letter2" > "$letter" ]]; then
                read letter2
                else
                echo "Invalid Input. Please enter A-Z one at a time finalised by a 0"
                fi

        done
else
echo "Invalid input. Please enter A-Z (capital) one at a time finalised by a 0"
fi
;;

Last edited by Ren_kun; 08-20-2011 at 04:07 AM..
# 26  
Old 08-20-2011
Well. It's possible to fix this script but it is long and complicated and no elegant. Better to write it from scratch. If you are agree I help you.

You need to use incremental development. The first script should be very simple:
Code:
while get input
  print input

Write this in bash. It is an infinitive loop, but there are 2 (right) ways to go out from it.
The second one should exit explicitly. Write a pseudocode for it. And so on.

At the end you will get an elegant small robust script. If you don't want it's simpler for me just to give you a ready solution. What do you prefer - to write by yourself (with my help) or just pass homework?
# 27  
Old 08-20-2011
Im going to start from scratch but this time try a case method. If i cant do it again ill get your help =].
# 28  
Old 08-20-2011
Ok. Just keep in mind that "a <= b" is equal to "not a > b".
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