Strings and its functions along with examples in python are presented

1. G H PATEL COLLEGE 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("INITIAL STRING: ")
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
• TO ACCESS 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
• JOINING OF 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
Updating a 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
• RETURNALIST OF THE WORDS IN STRING

11. SPLIT SEPARATOR
• DEFAULT SEPARATOR IS ANY SPACE(SPACE,NEWLINE,TAB)
• TO SPECIFY ANY OTHER SEPARATOR, SPECIFY IT EXPLICITLY.

12. JOIN METHOD
• USED TO 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!