Strings and list in python

Strings:

If alphanumeric characters are enclosed in single or double quotation marks, it indicates a string.

For example,

S1='hello'

S2='hai'

Print (type (S1))

#and your output will be str

Indexing:

It is used to extract a single character from a string.

For example,

S='hello'

print (S[1])

#and your output will be e

#e is present in the location given in input

Slicing:

It is used for printing a subset of the string.

For example,

S='Good day'

print (S[0:3])

#and your output will be Goo

#the characters present from 0th to 2nd(n-1) position is printed

Other functions:

1)len(S)-Used to find the length of the string .i.e.the number of characters in the string.

2)lower(S)-Used to print the string in lower case.

3)upper (S)-Used to print the string in upper case.

4)replace (S)-Used to replace the characters in a string.

Sample problems:

Problem-1

To reverse a string

Input

S='Good day'

k=S[::-1]

print (k)

#here S[-1]=y

Output

yad dooG

Problem-2

To find the number of vowels present in the given word.

Input

S='hello world'

U='aeiou'

Count=0

for i in range (Len(S)):

   if S[i] in U:

     Count=Count+1

   else:

     Continue

Output

3

List:

A list is a collection of elements of any data type. A list is mutable.

Syntax for list include,

• Square bracket
• Each term separated by comma 

We can perform all the above operations like indexing, slicing in list too. 
Example,

Code :

L=[1,2,3]

print(type(L))

print (L[1])

print (L)

print (len(L))

print (l[0:2])

Output

int

2

[1,2,3]
3

[1,2]