Strings in Python

Strings in Python

• 1.
  G H PATELCOLLEGE OF ENGINEERING & TECHNOLOGY, V. V. NAGAR, ACADEMIC YEAR: 2019-20 (EVEN SEM) CLASS: FINAL YEAR COMPUTER ENGINEERING 2180711-PYTHON PROGRAMMING BY: 160110107031, NARSINGANI AMISHA BATCH: 1B07 Presentation Topic: Strings in Python
• 2.
  WHAT ARE STRINGS? •STRINGS ARE ARRAYS OF BYTES REPRESENTING UNICODE CHARACTERS. • PYTHON DOES NOT HAVE A CHARACTER DATA TYPE, A SINGLE CHARACTER IS SIMPLY A STRING WITH A LENGTH OF 1. • SQUARE BRACKETS CAN BE USED TO ACCESS ELEMENTS OF THE STRING. • STRINGS IN PYTHON CAN BE CREATED USING SINGLE QUOTES OR DOUBLE QUOTES OR EVEN TRIPLE QUOTES. • FOR EXAMPLE: STRING1 = ‘WELCOME TO THE GCET WORLD’ STRING2 = “WELCOME EVERYONE!” STRING 3 = '''I'M A GEEK AND I LIVE IN A WORLD OF "GEEKS"'''
• 3.
  ITERATING THROUGH STRINGS •USING FOR LOOP WE CAN ITERATE THROUGH A STRING.
• 4.
  ACCESSING INDIVIDUAL CHARACTERS •WE CAN ACCESS INDIVIDUAL CHARACTERS OF STRING USING INDEXING. • INDEXING ALLOWS NEGATIVE ADDRESS REFERENCES TO ACCESS CHARACTERS FROM THE BACK OF THE STRING, E.G. -1 REFERS TO THE LAST CHARACTER, -2 REFERS TO THE SECOND LAST CHARACTER AND SO ON. (SEE THE BELOW FIGURE) • WHILE ACCESSING AN INDEX OUT OF THE RANGE WILL CAUSE AN INDEXERROR. P R O G R A M M I N G 0 1 2 3 4 5 6 7 8 9 10 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1
• 5.
  ACCESSING INDIVIDUAL CHARACTERS STRING1=“PROGRAMMING” PRINT("INITIALSTRING: ") PRINT(STRING1) PRINT("NFIRST CHARACTER OF STRING IS: ") PRINT(STRING1[0]) #OUTPUT: P PRINT("NLAST CHARACTER OF STRING IS: ") PRINT(STRING1[-1]) #OUTPUT: G
• 6.
  STRING SLICING • TOACCESS A RANGE OF CHARACTERS IN THE STRING, METHOD OF SLICING IS USED. • SLICING IN A STRING IS DONE BY USING A SLICING OPERATOR (COLON). • WE CAN ACCESS SUBSTRINGS USING SLICING • FOR EXAMPLE: C=“PROGRAMMING IS GOOD“ PRINT(C) D=C[5:7] PRINT(D) #OUTPUT: AM E=C[12:14] PRINT(E) #OUTPUT: IS
• 7.
  STRING CONCATENATION • JOININGOF TWO OR MORE STRINGS INTO A SINGLE ONE IS CALLED CONCATENATION. • THE + OPERATOR DOES THIS IN PYTHON. • THE * OPERATOR CAN BE USED TO REPEAT THE STRING FOR A GIVEN NUMBER OF TIMES. • FOR EXAMPLE: firstname = “Amisha” lastname = “Narsingani” fullname=firstname + lastname print(fullname) word=“hello “ echo = word*3 print(echo)
• 8.
  STRINGS ARE IMMUTABLE •UPDATION OR DELETION OF CHARACTERS FROM A STRING IS NOT ALLOWED. • THIS WILL CAUSE AN ERROR BECAUSE ITEM ASSIGNMENT OR ITEM DELETION FROM A STRING IS NOT SUPPORTED. • ALTHOUGH DELETION OF ENTIRE STRING IS POSSIBLE WITH THE USE OF A BUILT-IN DEL KEYWORD. • THIS IS BECAUSE STRINGS ARE IMMUTABLE, HENCE ELEMENTS OF A STRING CANNOT BE CHANGED ONCE IT HAS BEEN ASSIGNED. ONLY NEW STRINGS CAN BE REASSIGNED TO THE SAME NAME.
• 9.
  STRINGS ARE IMMUTABLE Updatinga character: STRING1 = "HELLO, I'M A GEEK" PRINT(STRING1) # UPDATING A CHARACTER OF THE STRING STRING1[2] = 'P' PRINT("NUPDATING CHARACTER AT 2ND INDEX: ") PRINT(STRING1) #TYPEERROR: ‘STR’ OBJECT DOES NOT SUPPORT ITEM ASSIGNMENT DEL STRING1[2] PRINT("NDELETING CHARACTER AT 2ND INDEX: ") PRINT(STRING1) #TYPEERROR: ‘STR’ OBJECT DOESN’T SUPPORT ITEM DELETION Updating Entire String: String1 = "Hello, I'm a Geek" print(String1) # Updating a String String1 = "Welcome to the Geek World" print("nUpdated String: ") print(String1) #doesn’t generate an error and gives output successfully del String1 #successfully deletes String1
• 10.
  SPLIT METHOD • RETURNALISTOF THE WORDS IN STRING
• 11.
  SPLIT SEPARATOR • DEFAULTSEPARATOR IS ANY SPACE(SPACE,NEWLINE,TAB) • TO SPECIFY ANY OTHER SEPARATOR, SPECIFY IT EXPLICITLY.
• 12.
  JOIN METHOD • USEDTO EFFICIENTLY CONSTRUCT STRINGS FROM MULTIPLE FRAGMENTS. STR.JOIN(ITERABLE) • RETURN A STRING WHICH IS THE CONCATENATION OF THE STRINGS IN ITERABLE. • A TYPEERROR WILL BE RAISED IF THERE ARE ANY NON-STRING VALUES IN ITERABLE. • FOR EXAMPLE: vowels = ['a', 'e', 'i', 'o', 'u’] print(vowels) ['a', 'e', 'i', 'o', 'u’] s = "-".join(vowels) print(s) 'a-e-i-o-u'
• 13.
  STRINGMETHODS
• 14.
  String methods
• 15.
  Thank You!