Guidelines

Predefined Reserved Words in Python - Keywords

Keywords are words that are reserved by a programming language because they have a special meaning and are used to perform specific syntactic operations.

These keywords form the basic syntax rules of the programming language and cannot be used as names for variables, functions, etc.

Typically, keywords are used to control the flow of programs or define data structures.

Major Keywords in Python

The major keywords used in Python are as follows.

1. Conditional Statements: if, else, elif

Defines conditional statements that are executed only if a certain condition is met.

You must include a colon (:) at the end of the line where the keyword is used, and the code block that executes depending on the condition is defined by indentation.

Example of if, else keywords in conditional statements

if x > 0:    # When x is greater than 0
    print("Positive")
elif x == 0: # When x is equal to 0
    print("Zero")
else:        # When x is less than 0
    print("Negative")

2. Loops: for, while

Defines loops that perform repeated actions.

You must include a colon (:) at the end of the line where the keyword is used, and the repetitive code block is defined by indentation.

Example of for, while keywords in loops

for i in range(5):  # Repeat 5 times from 0 to 4
    print(i)

while x < 10:       # Repeat while x is less than 10
    print(x)
    x += 1

3. Break Loop: break

Exits a loop when a certain condition is met within the loop.

Example of break keyword to break loops

for i in range(10):
    if i == 5:
        break       # Break the loop when i is 5
    print(i)

The above example stops the loop when i is 5, and prints numbers from 0 to 4.

4. Skip Iteration: continue

Skips the current iteration and proceeds to the next iteration when a certain condition is met within the loop.

Example of continue keyword to skip iteration

for i in range(10):
    if i % 2 == 0:
        continue    # Skip the iteration when i is even
    print(i)

The above example skips the iteration when i is even and prints only odd numbers.

5. Define Function: def

A function represents a block of code that performs a specific task. You define a function using the def keyword.

Example of def keyword to define functions

def add(x, y):  # Define a function add that takes two arguments x, y
    return x + y

The above example defines an add function that returns the sum of two arguments x and y.

6. Return Result from Function: return

The return keyword returns the result of the function's execution.

Example of return keyword to return value from function

def add(x, y):
    return x + y  # Return the sum of x and y

7. Define Class: class

A class is a user-defined data type that bundles data and functions that operate on the data.

The below example defines a Dog class and initializes the name attribute using the __init__ method.

Classes are a fundamental concept in Python and will be covered in detail in a later lesson.

Example of class keyword to define classes

class Dog:  # Define the Dog class
    def __init__(self, name):
        self.name = name

8. Handle Exceptions: try, except

Handles exceptional situations in the code.

If an exception occurs within the try block, it moves to the except block to handle the exception.

Below code handles ZeroDivisionError, an exception that occurs when dividing by zero.

Example of try, except keywords to handle exceptions

try:
    print(10 / 0)  # Exception occurs when dividing by zero
except ZeroDivisionError:
    print("Cannot divide by zero")

The above code handles the exception of dividing by zero and prints "Cannot divide by zero."

Aside from these, Python offers a wide variety of keywords that help control the program flow and process data.

Coding Practice

Enter the code emphasized in the practice screen: random_number = random.randint(1, 10).

random.randint(1, 10) generates a random integer between 1 and 10.

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In Python, the 'if', 'else', 'elif' keywords are used to define conditional statements.

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