How can I find the first occurrence of a sub-string in a python string

Question

So if my string is  the dude is a cool dude   I d like to find the first index of  dude    mystring findfirstindex  dude     should return 4   What is the python command for this  Thanks

User · Answer

def find pos chaine x        for i in range len chaine            if chaine i    x               return  yes  i      return  no

User · Answer

to implement this in algorithmic way  by not using any python inbuilt function    This can be implemented as  def find pos string word        for i in range len string  - len word  1           if string i i len word      word              return i     return  Not Found   string    the dude is a cool dude  word    dude1  print find pos string word     output 4

User · Answer

find     gt  gt  gt  s    the dude is a cool dude   gt  gt  gt  s find  dude   4

User · Answer

verse    quot If you can keep your head when all about you n  Are losing theirs and blaming it on you  nIf you can trust yourself when all men doubt you  n  But make allowance for their doubting too  nIf you can wait and not be tired by waiting  n  Or being lied about  don   t deal in lies  nOr being hated  don   t give way to hating  n  And yet don   t look too good  nor talk too wise  quot  enter code here  print verse   1  What is the length of the string variable verse  verse length   len verse  print  quot The length of verse is     quot  format verse length    2  What is the index of the first occurrence of the word  and  in verse  index   verse find  quot and quot   print  quot The index of the word  and  in verse is    quot  format index

User · Answer

Quick Overview  index and find  Next to the find method there is as well index  find and index both yield the same result  returning the position of the first occurrence  but if nothing is found index will raise a ValueError whereas find returns -1  Speedwise  both have the same benchmark results   s find t      returns  -1  or index where t starts in s s index t     returns  Same as find  but raises ValueError if t is not in s   Additional knowledge   rfind and rindex      In general  find and index return the smallest index where the passed-in string starts  and rfind and rindex return the largest index where it starts   Most of the string searching algorithms search from left to right  so functions starting with r indicate that the search happens from right to left     So in case that the likelihood of the element you are searching is close to the end than to the start of the list  rfind or rindex would be faster    s rfind t     returns  Same as find  but searched right to left s rindex t    returns  Same as index  but searches right to left   Source  Python  Visual QuickStart Guide  Toby Donaldson

[python] How can I find the first occurrence of a sub-string in a python string?

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