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Fibonacci series -going into infinite loop

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# 1  
Old 12-09-2015
Linux Fibonacci series -going into infinite loop
Hello, I am a beginner to shell programming. Coded the following for Fibonacci series.

Code:
#!/bin/bash
fib()  {

i=0
j=1
arr[0]=0
arr[1]=1

echo "enter the limit:"
read n

while [ $i -lt $n ]
do
    fo= expr $j - 1
    f1=$j
    f2= expr $j + 1
    arr[$f2]= expr ${arr[$f1]} + ${arr[$f0]}
    echo ${arr[$f2]}
    
    i= expr $i + 1
    j= expr $j + 1
    
done
}

fib



The program is going into infinite loop. From debugging I understood that updated i,j values are not being carried to next iteration of while loop. Why is it so? Can someone please help.
Last edited by Don Cragun; 12-09-2015 at 02:55 PM.. Reason: Add CODE and ICODE tags.
# 2  
Old 12-09-2015
Hi, you must use backquote when you execute commande from variable affectation:
Code:
i=`expr $i + 1`

or
Code:
i=$(expr $i + 1)

or under bash, you needn't use expr, just:
Code:
((i++))

# 3  
Old 12-09-2015
Please use code tags as required by forum rules!

You need to use command substitution for all your expr assignments, e.g.
Code:
i=$(expr $i + 1)

# 4  
Old 12-09-2015
Thank you disedorgue & RudiC. The changes worked. ;-)
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