python - How do you count for variations of substring in string module? -

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• string count overlapping occurrences 17 answers

just started learning python. had create function count sub-string within string. decided use count() function of string module doesn't hoping for.

it seems count() function iterate through string , if find sub-string, move add count continue it's iteration @ end of sub-string.

below code , test running:

def count(substr,thestr):     counter = 0     counter = thestr.count(substr, 0, len(thestr))     return counter    print(count('is', 'mississippi'))            # expected count: 2     pass  print(count('an', 'banana'))                 # expected count: 2     pass  print(count('ana', 'banana'))            # expected count: 2     test failed: count: 1  print(count('nana', 'banana'))           # expected count: 1     pass  print(count('nanan', 'banana'))              # expected count: 0     pass  print(count('aaa', 'aaaaaa'))            # expected count: 5     test failed: count: 2 

try taking individual sub strings of length of desired string, , checking them:

def count(sub, whole):     total = 0     in range(0, len(whole)-len(sub)+1):             if sub == whole[i:i+len(sub)]:                     total+=1     return total 

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>>> print(count('is', 'mississippi'))            2 >>> # expected count: 2     pass ...  >>> print(count('an', 'banana'))                 2 >>> # expected count: 2     pass ...  >>> print(count('ana', 'banana'))            2 >>> # expected count: 2     pass ...  >>> print(count('nana', 'banana'))           1 >>> # expected count: 1     pass ...  >>> print(count('nanan', 'banana'))              0 >>> # expected count: 0     pass ...  >>> print(count('aaa', 'aaaaaa'))            4 >>> # expected count: 4     pass ...