how to do recursion in python outside and inside loop

Question

Below is the python code to get the longest concat str with count I am not able to call the function again when in loop and out side loop I am not able to access suffixString

if i call outside the loop it's

  t = {"asds":"asds","asas":"asas"}

  def checkIfitsLongest(str1):
        for i in range(1, len(str1)-1):
            suffixString = str1[i+1:-1]
                if t.has_key(suffixString):
                    break
        checkIfitsLongest(suffixString)

Answer 1

Putting some well-positioned print debugging statements we can see that your problem is not with scoping of the checkIfitsLongest function or suffixString variable.

t = {"asds":"asds","asas":"asas"}

def checkIfitsLongest(str1):
    print "checking", str1
    for i in range(1, len(str1)-1):
        suffixString = str1[i+1:-1]
        print "suffix", suffixString
        if t.has_key(suffixString):
            break
    checkIfitsLongest(suffixString)

Now run in the interpreter:

>>> checkIfitsLongest("asdf")
checking asdf
suffix d
suffix 
checking 

Traceback (most recent call last):
  File "<pyshell#5>", line 1, in <module>
    checkIfitsLongest("asdf")
  File "C:/Users/me/Desktop/cccc.py", line 10, in checkIfitsLongest
    checkIfitsLongest(suffixString)
  File "C:/Users/me/Desktop/cccc.py", line 10, in checkIfitsLongest
    checkIfitsLongest(suffixString)
UnboundLocalError: local variable 'suffixString' referenced before assignment
>>> 

So we can see that suffixString is being passed down correctly. However it is never initialized when you pass an empty string into the function (never entering the for loop).

You need to consider how to check your recursive base case. Usually you do this at the beginning of your function.