Bash- add up two arrays variables' to third array's variable

Question

i have three arrays A, B, C. Array A-B values are being parsed from file and i want them to add up into array C.

#!/bin/bash
i=0
A=()
B=()
C=()
while read line
do
  A[i]="$(echo $line| cut -d\  -f4)"
  B[i]="$(echo $line| cut -d\  -f11)"
  echo ${A[i]} " and " ${B[i]}
  # outputs correct values
  C[i]=`expr ${A[i]} + ${B[i]}`
  echo ${C[i]} 
  # no output
  i=$((i+1))
done < ~/file
exit 0

what is wrong with that assignment?

complete line from script:

hitEnd[i]=`expr ${hitLength[i]}+${hitStart[i]}`
echo "${hitEnd[i]}"
#no output

@louxiu complete error output: ./getSum.sh line 131: 635: command not found.. (635 is the array B's value) — teutara
– teutara, Commented Dec 1, 2012 at 7:36
@louxiu at the first echo it outputs the correct values, but at the error output there is no value shown for array A's value.. — teutara
– teutara, Commented Dec 1, 2012 at 7:45
I can't reproduce the problem. I ran your script and it worked as expected. There must be something in the real script that you're not showing. — Barmar
– Barmar, Commented Dec 1, 2012 at 8:40

user339222 · Accepted Answer · 2012-12-01 08:42:13Z

1

the line:

    C[i]=`expr ${A[i]} + ${B[i]}`

while give an error if one of the two operands is missing. If that is expected, i.e. having empty fields in the files, then:

   C[i]=$((${A[i]:-0}+${B[i]:-0}))

Should work.

answered Dec 1, 2012 at 8:42

user339222

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Comments

louxiu · Accepted Answer · 2012-12-01 07:45:10Z

-1

The script look correctly. You may not construct the array correctly.

And always double quote the variable to avoid some error.

answered Dec 1, 2012 at 7:45

louxiu

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