Recursive functions in Bash Scripting - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a recursive function that prints numbers from n down to 1.

Bash Scripting

print_numbers() {
  if [ $1 -le 0 ]; then
    return
  fi
  echo $1
  print_numbers [1]
}

print_numbers 5

Drag options to blanks, or click blank then click option'

A$(( $1 + 1 ))

B$1 + 1

C$(( $1 - 1 ))

D$1 - 1

Attempts:

3 left

💡 Hint

Common Mistakes

Using $1 + 1 which increases the number and causes infinite recursion.

Not using arithmetic expansion, causing syntax errors.

The function calls itself with the argument decreased by 1 to count down.

2fill in blank

medium

Complete the code to calculate the factorial of a number recursively.

Bash Scripting

factorial() {
  if [ $1 -le 1 ]; then
    echo 1
  else
    local prev=$(factorial [1])
    echo $(( $1 * prev ))
  fi
}

factorial 5

Drag options to blanks, or click blank then click option'

A$1 + 1

B$1 - 1

C$(( $1 + 1 ))

D$(( $1 - 1 ))

Attempts:

3 left

💡 Hint

Common Mistakes

Using $1 - 1 without arithmetic expansion causes errors.

Increasing the argument instead of decreasing it.

The function calls itself with the argument decreased by 1 to compute factorial.

3fill in blank

hard

Fix the error in the recursive function that sums numbers from 1 to n.

Bash Scripting

sum_to_n() {
  if [ $1 -eq 1 ]; then
    echo 1
  else
    local prev=$(sum_to_n [1])
    echo $(( $1 + prev ))
  fi
}

sum_to_n 5

Drag options to blanks, or click blank then click option'

A$(( $1 - 1 ))

B$(( $1 + 1 ))

C$1 + 1

D$1 - 1

Attempts:

3 left

💡 Hint

Common Mistakes

Increasing the argument causes infinite recursion.

Not using arithmetic expansion leads to syntax errors.

The function must call itself with the argument decreased by 1 to sum correctly.

4fill in blank

hard

Fill both blanks to create a recursive function that computes the nth Fibonacci number.

Bash Scripting

fib() {
  if [ $1 -le 1 ]; then
    echo $1
  else
    local a=$(fib [1])
    local b=$(fib [2])
    echo $(( a + b ))
  fi
}

fib 6

Drag options to blanks, or click blank then click option'

A$(( $1 - 1 ))

B$1 - 1

C$(( $1 - 2 ))

D$1 - 2

Attempts:

3 left

💡 Hint

Common Mistakes

Using $1 - 1 without $(( )) causes errors.

Mixing arithmetic and string subtraction.

Fibonacci of n is sum of fib(n-1) and fib(n-2), using arithmetic expansion.

5fill in blank

hard

Fill all three blanks to create a recursive function that reverses a string.

Bash Scripting

reverse() {
  if [ -z "$1" ]; then
    echo ""
  else
    local first=${1:0:1}
    local rest=${1:1}
    local rev_rest=$(reverse [1])
    echo "${rev_rest}[2]${first}[3]"
  fi
}

reverse "hello"

Drag options to blanks, or click blank then click option'

A"$rest"

B"$first"

C""

D" "

Attempts:

3 left

💡 Hint

Common Mistakes

Using the first character instead of the rest in recursive call.

Adding spaces between characters when reversing.

The function calls reverse with the rest of the string, then appends the first character at the end.