Bash Script Binary Search

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A binary search needs the max and min boundaries of the search. Starting at zero is great, but your last variable is a little off. Try: last=$(($#students[@]} - 1)) the – 1 will put your array at the correct size (arrays start at zero and go to one less of their size.)

After that try the following pseudo code:

while (last is <= first) 
  middle = midway point between first and last

  // make sure that your comparing just the names "Ann",
  // not your whole string "Ann:A"
  if (students[middle] == student)
    exit loop
  else if (students[middle] < student)
    first = middle + 1
  else if (students[middle] > student)
    last = middle - 1

I’m not great at bash scripting, so I won’t try and fix (if it even needs fixing) most of your syntax. The pseudo code should get you most of the way there if you figure out the syntax.

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