Built in Function#

Python has several functions that are readily available for use. These functions are called built-in functions.

Useful Built in Functions#

len() function#

You can pass the len() function to a string value (or a variable containing a string), and the function evaluates to the integer value of the number of characters in that string.

len('hello')

5

input() function#

If you need to interact with user, either to get data input or to provide some sort of result. Asking the user to provide some type of input, Python provides us with built-in input() functions to take the input from the keyboard.

This function first takes the input from the user, converts it into a string and stores it in a variable. It does not evaluate the expression; it just returns the complete statement as string. When the input() function is called it stops the program and waits for the user’s input. When the user presses enter, the program resumes and returns what the user has typed.

You can prompt the user to input a string and assign it to a variable.

user = input("What is your name? ")
print(user)

>>> What is your name? Ali
Ali

bin() function#

The bin() method converts an integer to its binary value and returns it.

num = 100
print(bin(num))  # print binary number

0b1100100

The bin() method returns, the binary string equivalent to the given integer and TypeError for a non-integer argument.

Note

The prefix 0b in the output 0b1100100 represents that the result is a binary string.

oct() function#

The oct() function takes an integer number and returns its octal representation.

num = 100
print(oct(num))  # print octal number

0o144

The oct() function returns an octal string from the given integer number.

hex() function#

The hex() function converts an integer number to the corresponding hexadecimal string. The hex() function converts an integer to the corresponding hexadecimal number in string form and returns it.

num = 100
print(hex(num))  # print hex number

0x64

The returned hexadecimal string starts with the prefix 0x indicating it’s in hexadecimal.

round() function#

The round() function returns a floating point number that is a rounded version of the specified number, with the specified number of decimals.

num = round(5.12345, 2)
print(num)

5.12

id() function#

All objects in Python when created, has its own unique id (memory location), the id() function returns a unique id of the specified object.

num = 5.12
id(num)

1707832475504

The id is the object’s memory address, and will be different for each time you run the program. (except for some object that has a constant unique id, like integers from -5 to 256).