Operations on Strings(Part-1)2 min read

Some Operations on String are:-

  • Traversing
  • Concatenation
  • Replication
  • Slicing
  • Membership
  • Reversing

1.Traversing a String

Traversing string means travelling across the string or to access any(or all) the elements of string one after the other.It is generally done by index value or loops.

#Individual elements can be accessed by index value.
s="Hello!"
print(s[1])
#Only integer values can be used as index as other will result in type error.For eg:-
print(s['t'])
Output:
e
Traceback (most recent call last):
    File "<stdin>",line 6, in <module>
TypeError: string indices must be integers.

Also we can start index value from both sides, i.e. from left or from right.Left index values start from 0 and right index values start from -1.Python-Index
Here s[0]=s[-6] and so on.Each character is associated with a index value and can be accessed through it.

Iterating through String

Each character can also be accessed sequentially using for or while loop:
For Example:-

#Iterating through string using for loop
string='Python'
for i in string:
    print(i)
Output:-
P
y
t
h
o
n

2.Concatenation

Concatenation means to link(or group) things in a series or chain.
It creates a new string by joining two(or more than two) strings.The + operator(or concatenation operator) joins strings writtern on either side of that operator and creates new string.

s="Python "
t="Language"
print(s+t)
#Remember we can't add 'str'(string) and 'int'(integer) objects otherwise it will throw an error.
print(1+s)
#But we can do the same by converting integer to string first.
print(str(1)+s)
Output:-
Traceback (most recent call last):
    File "<stdin>",line 6, in <module>
TypeError: unsupported operand type(s) for +: 'int' and 'str'
1Python

Important:-

Strings are immutable in Python.It means once created they cannot be changed. Every-time we perform any operation python don’t modify the string and creates a new string. To verify this we can try to change a character from the string using its index.
>>>s=”Immutable”
>>>s[2]=’c’
TypeError: ‘s’ object does not support item assignment.

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