regexT.py

# ===================== SUMMARY OF re MODULE =====================
# re module is used for Regular Expressions in Python.
# Regular Expression means searching/finding a pattern inside a string.
# re.search() checks pattern anywhere in the string.
# re.match() checks pattern only at the beginning of the string.
# re.fullmatch() checks whether the whole string matches the pattern.
# re.findall() returns all matched values as a list.
# re.finditer() returns match objects one by one.
# re.sub() replaces matched pattern with another value.
# re.split() splits string based on a pattern.
# re.compile() stores a pattern so we can reuse it again and again.
# ===============================================================

import re                                                           # importing re module for regular expressions

text = "My name is Saad and my age is 22"                           # creating sample text

result = re.search("Saad", text)                                    # searching "Saad" anywhere inside text

print(result.group())                                               # prints matched text | Output: Saad

print(result.start())                                               # prints starting index of match | Output: 11

print(result.end())                                                 # prints ending index of match | Output: 15

result = re.search("Delhi", text)                                   # searching "Delhi" inside text

print(result is None)                                               # checks if no match found | Output: True

result = re.match("My", text)                                       # checking if text starts with "My"

print(result.group())                                               # prints matched starting text | Output: My

result = re.match("Saad", text)                                     # checking if text starts with "Saad"

print(result is None)                                               # checks if match failed | Output: True

result = re.fullmatch("My name is Saad and my age is 22", text)     # checking if full text matches exactly

print(result is not None)                                           # checks if full match happened | Output: True

numbers = re.findall(r"\d+", text)                                  # finding all continuous numbers from text

print(numbers)                                                      # prints all numbers as list | Output: ['22']

words = re.findall(r"[A-Za-z]+", text)                              # finding all alphabet words from text

print(words)                                                        # prints all words as list | Output: ['My', 'name', 'is', 'Saad', 'and', 'my', 'age', 'is']

for match in re.finditer(r"\d+", text):                             # finding numbers one by one as match objects
    print(match.group())                                            # prints matched number | Output: 22
    print(match.start())                                            # prints start index of number | Output: 31
    print(match.end())                                              # prints end index of number | Output: 33

new_text = re.sub(r"\d+", "25", text)                               # replacing full number with 25

print(new_text)                                                     # prints updated text | Output: My name is Saad and my age is 25

hidden_text = re.sub(r"\d", "*", text)                              # replacing each digit with star

print(hidden_text)                                                  # prints hidden digit text | Output: My name is Saad and my age is **

sentence = "apple,banana;orange grape"                              # creating sentence with different separators

parts = re.split(r"[,;\s]", sentence)                               # splitting by comma, semicolon, or space

print(parts)                                                        # prints split list | Output: ['apple', 'banana', 'orange', 'grape']

email = "saad123@gmail.com"                                         # creating email string

result = re.search(r"\w+@\w+\.\w+", email)                          # searching basic email pattern

print(result.group())                                               # prints matched email | Output: saad123@gmail.com

mobile = "9876543210"                                               # creating mobile number string

result = re.fullmatch(r"\d{10}", mobile)                            # checking exactly 10 digits

print(result.group())                                               # prints valid mobile number | Output: 9876543210

password = "Saad@123"                                               # creating password string

print(re.search(r"[A-Z]", password).group())                        # prints first uppercase letter | Output: S

print(re.search(r"[a-z]", password).group())                        # prints first lowercase letter | Output: a

print(re.search(r"\d", password).group())                           # prints first digit | Output: 1

print(re.search(r"[@#$%]", password).group())                       # prints first special character | Output: @

name = "Saad Arfin"                                                 # creating full name string

result = re.search(r"(\w+)\s(\w+)", name)                           # grouping first name and last name

print(result.group())                                               # prints full matched name | Output: Saad Arfin

print(result.group(1))                                              # prints first group | Output: Saad

print(result.group(2))                                              # prints second group | Output: Arfin

date = "28-06-2026"                                                 # creating date string

result = re.search(r"(?P<day>\d{2})-(?P<month>\d{2})-(?P<year>\d{4})", date)  # making named groups for day, month, year

print(result.group("day"))                                         # prints day from date | Output: 28

print(result.group("month"))                                       # prints month from date | Output: 06

print(result.group("year"))                                        # prints year from date | Output: 2026

text2 = "python is easy. PYTHON is powerful."                       # creating another sample text

print(re.findall(r"python", text2))                                 # finds lowercase python only | Output: ['python']

print(re.findall(r"python", text2, re.I))                           # finds python ignoring case | Output: ['python', 'PYTHON']

pattern = re.compile(r"\d+")                                        # compiling number pattern for reuse

print(pattern.findall("Marks are 80 and 90"))                       # finds all numbers using compiled pattern | Output: ['80', '90']

print(pattern.sub("XX", "Marks are 80 and 90"))                     # replaces all numbers using compiled pattern | Output: Marks are XX and XX