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RevisedNotesStrings

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  • Day : Sunday
  • Date : 2025-09-07
  • Time : 16:05
  • Tags : #python #revised #strings
  • References : [[RevisedNotes]] , [[FunctionsStrings]] , [[ImportantQuestionsSrtings1]]
  • Branch of : Python > RevisedNotes > RevisedNotesStrings
  • Author : dx

Notes

Strings

  • len() : length, iterable must, else TypeError

  • l.upper(), l.lower() : return new str, none Error

  • l.capatlize() : first letter of first word , None

  • l.title() : First letter of each word ,None

  • l.strip(), l.rstrip(), l.lstrip() : it will by default remove space \n \t \r \f \v padding, or specified padding even !@ can remove !!!!!!!!!!@@@@@@@ , None Error

  • l.replace(oldsubstr,newstr,count) : it will give a new str by repalacing that , TypeError if not string, or not at least 2 arg, no error if sub str not found

  • l.find(substr, start, end) or l.rfind() : it will give the index of 1sst occuracnce , from left or , right , Give -1 if not found , NO error

  • l.index(substr, start, end), l.rfind(): it will give the first occurance of str , from left/right , ValueError if not found

  • l.count(str, start, end) : it will count the occurance of str , no error , even not index out of range error

  • l.split("SEPERAROR", MAXsplits) / l.rsplit() : it will split the str into parts acc to substring passed, it doesn’t give separator in splitted list , None , GIVES LIST , Gives full str if separator not present

  • l.partition("SEPERATOOR") : it will give a TUPLE of first split of str with the seperator , ValueError if not present

  • "SEPERATOR".join(iterable) : Join the iterable with the seperator, TypeError if not iterable or not str

  • l.startswith(substr, start, end) / l.endswith() : Return true if condition True, Output Type bool, no Error

  • str.isalpha() / str.isdigit() / str.isalnum() / str.isspace() / str.islower() / str.isupper() / str.istitle() : Return True or False if the condition satisfy, NO arg required

  • l.zfill(TOTALLENGTH) : it will pad the str left with zeroes and preserve sign , Pad as total length

  • str.encode()

    • Syntax: string.encode(encoding='utf-8')

    • Input: str

    • Output: bytes

    • Error: UnicodeEncodeError if characters can’t be encoded.

    • Example: "hello".encode() → b'hello'

    "hello".encode()  # b'hello'   (5 bytes: 68 65 6c 6c 6f in hex)

"♥".encode("utf-8")  # b'\xe2\x99\xa5'  (3 bytes in UTF-8)

    b is byte literal

  • str.format() / str.format_map()

    • Syntax: string.format(*args, **kwargs) / string.format_map(mapping)

    • Input: str with placeholders

    • Output: str

    • Error: KeyError / IndexError if placeholders missing.

    • Example: "Hello {}".format("World") → "Hello World"

  • str.casefold()

    • Syntax: string.casefold()

    • Input: str

    • Output: str

    • Error: None

    • Example: "Straße".casefold() → "strasse"

    • Use: For aggressive lowercasing → best for case-insensitive comparison, especially with non-English text.