import re
pattern=re.compile('python') 
print(type(pattern))

Output:
<class 're.Pattern'>

#Python program to find the pattern ab in a target string ababbaba and find the no. of occu
import re
count=0
pattern=re.compile('ab')
matcher=pattern.finditer('ababbaba') 
for m in matcher:
    count+=1
    #print('match is available at start index',m.start())
    print('start:{},end:{},group:{}'.format(m.start(),m.end(),m.group())) 

print('the no. of occurences is:',count)

Output:
start:0,end:2,group:ab
start:2,end:4,group:ab
start:5,end:7,group:ab
the no. of occurences is: 3

#finditer(): import    re
matcher=re.finditer('[abc]','a7b@k9z') 
for m in matcher:
    print(m.start(),'....',m.group())

Output:
0 .... a
2 .... b

#match()
import re
s=input('enter pattern to check') 
m=re.match(s,'abcdefgh')
if m!=None:
    print('match is available at the begining of the string') 
    print('start index:{} and end index:{}'.format(m.start(),m.end()))
else:
    print('match is not available at the begining of the string')

Output:
enter pattern to checkabc
match is available at the begining of the string
start index:0 and end index:3

#fullmatch()
import re
s=input('enter pattern to check') 
m=re.fullmatch(s,'abcdefgh')
if m!=None:
    print('full string matched') 
else:
    print('full string not matched')

Output:
enter pattern to checkabcdefgh
full string matched

#search()
import re
s=input('enter pattern to check') m=re.search(s,'abaabaaab')
if m!=None:
    print('match is available')
    print('First occurence with start index:{} and end index:{}'.format(m.start(),m.end())) 
else:
    print('match is not available')

Output:
enter pattern to checkaaa
match is available First occurence with start index:5 and end index:8

#findall():
import re
l=re.findall('[0-9]','a7b9k6z') 
print(l)

Output:
['7', '9', '6']

#split():
import re
l=re.split(' ','Silan Software') 
for k in l:
    print(k)

Output:
Silan
Software

#Regular expression to represent 10 digits mobile number
import re
s=input('enter mobile number to validate') 
m=re.fullmatch('[6-9]\d{9}',s)
if m!=None:
    print(s,'is valid mobile number') 
else:
    print(s,'is not valid mobile number')

Output:
enter mobile number to validate9439202111
9439202111 is valid mobile number

#Regular expression to check valid or invalid gmail id
import re
s=input('enter mail id:')
m=re.fullmatch('\w[a-zA-Z0-9_.]*@gmail[.]com',s) 
if m!=None:
    print('valid gmail id') 
else:
    print('invalid gmail id')

Output:
enter mail id:trilochan4u@gmail.com
valid gmail id

#Regular expression to check valid or invalid mail id
import re
s=input('enter mail id:')
m=re.fullmatch('\w[a-zA-Z0-9_.]*@[a-z0-9]+[.][a-z]+',s) 
if m!=None:
    print('valid mail id') 
else:
    print('invalid mail id')

Output:
enter mail id:govind_silan@3s.net
valid mail id