Python Functions and Conditional Statements

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Questions and Answers

Which part of a function definition is used to identify what the function does?

  • Docstring (correct)
  • Function name
  • Return statement
  • Parameters

In Python, all function parameters are passed by value.

False (B)

What is the purpose of a return statement in a function?

To return a value from the function.

The keyword ___ marks the start of a function header.

<p>def</p> Signup and view all the answers

Match the following components of a function with their descriptions:

<p>Function name = Identifies the function uniquely Parameters = Values passed to the function Docstring = Explains what the function does Function body = Contains the statements that execute</p> Signup and view all the answers

Which statement will be executed when the condition in an if statement is true?

<p>The statements inside the if block (D)</p> Signup and view all the answers

An if-else statement can only execute one block regardless of how many conditions are present.

<p>True (A)</p> Signup and view all the answers

What is the primary purpose of conditional statements in programming?

<p>To control the flow of program execution based on conditions.</p> Signup and view all the answers

In Python, the structure used to control the execution of code based on conditions is called a(n) __________.

<p>if statement</p> Signup and view all the answers

Match the following types of statements with their characteristics:

<p>If statement = Executes block if condition is true If-else statement = Executes one block if condition is true and another if false Nested if statement = An if statement inside another if statement If-elif ladder = Used for checking multiple conditions sequentially</p> Signup and view all the answers

What will happen if you forget to properly indent the code after an if statement?

<p>It will raise an indentation error (A)</p> Signup and view all the answers

An if statement can have multiple else statements.

<p>False (B)</p> Signup and view all the answers

Explain what a 'while loop' does in Python.

<p>A while loop executes a block of code repeatedly as long as a specified condition is true.</p> Signup and view all the answers

What happens to the else clause in a while loop if a break statement is executed?

<p>The program skips the else clause. (A)</p> Signup and view all the answers

In Python, a for loop can have an else clause.

<p>True (A)</p> Signup and view all the answers

Explain when the else clause of a while loop is executed.

<p>The else clause of a while loop is executed when the condition becomes false, and the loop doesn't end due to a break statement.</p> Signup and view all the answers

The syntax of a for loop begins with the keyword '____'.

<p>for</p> Signup and view all the answers

Match the type of loop to their primary characteristic:

<p>While Loop = Repeatedly tests a condition For Loop = Iterates over a sequence For Else Loop = Executes if the loop is not terminated by a break While Else Loop = Executes if the condition becomes false</p> Signup and view all the answers

What will be the output of the following code snippet?

counter = 0
while counter < 3:
   print("Inside loop")
   counter = counter + 1
else:
   print("Inside else")

<p>Inside loop Inside loop Inside loop Inside else (B)</p> Signup and view all the answers

The for loop can only iterate through lists in Python.

<p>False (B)</p> Signup and view all the answers

What is the purpose of the statement 'sum = sum + val' in the for loop example?

<p>It accumulates the total sum of the numbers in the list.</p> Signup and view all the answers

What will be the output of the following code?

 i = 10
 if (i == 10):
     print("i is 10")
 elif (i == 15):
     print("i is 15")
 else:
     print("i is not present")

<p>i is 10 (B)</p> Signup and view all the answers

In a while loop, the body of the loop executes only when the test expression evaluates to True.

<p>True (A)</p> Signup and view all the answers

What is the purpose of an 'elif' statement in an if-else ladder?

<p>To check additional conditions after the initial if statement.</p> Signup and view all the answers

The statement print("Hello TY") will execute _______ times if the count variable starts at 0 in the given while loop.

<p>3</p> Signup and view all the answers

Match the type of loop with its description:

<p>While Loop = Repeats as long as the condition is true For Loop = Iterates over a sequence or collection Nested Loop = A loop inside another loop For Else = Executes a block when the loop finishes without a break</p> Signup and view all the answers

Which statement will be executed when i = 20 in the following code?

 if (i == 10):
     print("i is 10")
 elif (i == 15):
     print("i is 15")
 elif (i == 20):
     print("i is 20")
 else:
     print("i is not present")

<p>i is 20 (B)</p> Signup and view all the answers

In an if-elif-else ladder, all conditions are evaluated even after one has been found to be true.

<p>False (B)</p> Signup and view all the answers

What happens if none of the conditions in an if-elif-else ladder are met?

<p>The else statement is executed.</p> Signup and view all the answers

What is the output of the following function call: changeme([10, 20, 30]) in the first example?

<p>Values outside the function: [10, 20, 50] (D)</p> Signup and view all the answers

In the function changeme(mylist), the line mylist = [1,2,3,4] changes the original list object passed to the function.

<p>False (B)</p> Signup and view all the answers

What type of argument must match exactly in order with the function call?

<p>Required arguments</p> Signup and view all the answers

In Python, functions can be called with arguments preceded by a variable name followed by a '=' sign, known as ______.

<p>Keyword arguments</p> Signup and view all the answers

Which of the following is a characteristic of keyword arguments?

<p>They can be provided in any order. (C)</p> Signup and view all the answers

Match the following terms with their descriptions:

<p>Required Arguments = Must match exactly in order Keyword Arguments = Can be in any order based on a name Default Arguments = Used when a value is unspecified Variable-length Arguments = Allows passing a variable number of arguments</p> Signup and view all the answers

The function printme() will execute without errors if called with no arguments.

<p>False (B)</p> Signup and view all the answers

What happens when the function printme() is called without arguments?

<p>TypeError: printme() takes exactly 1 argument (0 given)</p> Signup and view all the answers

What type of variable can be accessed all over the program?

<p>Global Variable (C)</p> Signup and view all the answers

Lambda functions can return multiple expressions.

<p>False (B)</p> Signup and view all the answers

What is the syntax for defining a lambda function with two arguments?

<p>lambda arg1, arg2: expression</p> Signup and view all the answers

In Python, variables declared inside a function body are known as ______.

<p>Local Variables</p> Signup and view all the answers

What will be the output of the following code: sum = lambda arg1, arg2: arg1 + arg2; print(sum(5, 10))?

<p>15 (C)</p> Signup and view all the answers

A return statement without an expression will send back a value of zero.

<p>False (B)</p> Signup and view all the answers

In the function definition def sum(arg1, arg2):, what is the purpose of 'arg1' and 'arg2'?

<p>They are parameters of the function.</p> Signup and view all the answers

Flashcards

Flow of Control

A decision-making statement that controls the flow of a program based on whether a condition is true or false.

If Statement

A statement that executes a block of code only if a specific condition is met.

Else Statement

A statement that provides an alternative block of code to be executed if the initial condition is false.

Nested If Statement

An If statement within another If statement, allowing for multiple levels of conditional execution.

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If-Elif Ladder

A series of If-Else statements where each condition is evaluated in sequence, and the corresponding block is executed if the condition is true.

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Indentation

The use of whitespace, usually spaces or tabs, to define the scope of code blocks in Python.

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While Loop

A statement that repeatedly executes a block of code as long as a certain condition remains true.

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For Loop

A statement that executes a block of code for each item in an iterable (e.g., list, string).

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def

A keyword that marks the start of a function definition. It's followed by the function's name, optional parameters, and a colon.

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Function name

A unique identifier for functions in Python. It follows the same rules as other identifiers, meaning it can include letters, numbers, and underscores, but it must start with a letter or underscore.

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Parameters

Inputs that a function receives to perform its operations. Like ingredients in a recipe, they give a function the details it needs to work.

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Docstring

A special type of string that documents what a function does, explaining its functionalities, inputs, and outputs. It's the function's descriptive manual.

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Function Body

The code that is executed when a function is called. It's the core of the function, containing the instructions for completing the task.

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While Loop with Else

A statement that is used to provide an alternative block of code to be executed if the condition in the while loop is false. The else block will execute only if the loop completes normally without being interrupted by a break statement.

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For Loop with Else

A statement that is used to provide an alternative block of code to be executed if the for loop finishes without being interrupted by a break statement.

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Break Statement

A statement that immediately terminates a loop, even if the loop condition is still true.

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Continue Statement

This statement tells the interpreter to execute the next iteration of the loop immediately

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Range Function

A function that generates a sequence of numbers. It takes three arguments: start, stop (exclusive) and step, and produces a sequence that increments from start to stop, with a step size between each number.

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Lists vs Arrays

A list is a mutable data structure, which means you can change its elements after it is created. Arrays are fixed-size data structures and their elements are not mutable, in contrast to mutable lists

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If-elif-else ladder

A conditional statement that offers multiple conditions to check. If one condition is true, its code block is executed, and the remaining conditions are skipped. If all conditions are false, the code block in the 'else' statement is executed.

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Else statement with while loop

A code block within a While loop that is executed only when the loop's condition becomes false. It is used to perform actions after the loop has completed its iterations.

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Nested loops

Loops nested within other loops, allowing for multiple levels of iteration.

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For else statement

A statement that combines a 'For' loop with an 'else' statement. The 'else' block executes only if the entire 'For' loop completes its iterations without encountering a 'break' statement.

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Lambda Functions

Anonymous functions in Python. They are defined using the keyword lambda. They can have any number of arguments, but only one expression. They are often used for short, reusable code snippets.

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Function Definition

A statement that defines a function. It includes the function name, arguments, and the code block that will be executed when the function is called.

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return Statement

A statement that exits a function and returns a value to the calling code. If no value is specified, it returns None.

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Local Variable

A variable that is declared inside a function. It can only be accessed within the function's scope.

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Global Variable

A variable that is declared outside any function. It can be accessed from anywhere in the program.

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Variable Scope

The part of a program where a variable is accessible. Local variables have limited scope, while global variables have wider scope.

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Function Call

A function call inside another function. This allows you to reuse or call functions within other functions.

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Function Execution

The process of executing function code. When a function call is made, the code inside the function is executed.

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What is a Python function?

In Python, a function is a block of reusable code that performs a specific task. It's defined using the 'def' keyword followed by the function name, parentheses, and a colon. Functions can take arguments (inputs) and return values (outputs).

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How do you call a function?

In Python, a function can be called by using its name followed by parentheses. You can pass arguments inside the parentheses to provide the function with data to work with. After the function finishes executing, it returns a value (if it's defined to return something).

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What are function arguments?

In Python, arguments passed to a function are variables that hold the values the function needs to work with. These arguments can be used within the function's code to perform operations and modify them.

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What are required arguments?

Required arguments are the ones that a function must have in order to work correctly. These arguments must be passed to the function in the exact order they are expected. If any required arguments are missing, an error will occur.

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What are keyword arguments?

Keyword arguments allow you to pass values to a function using their names instead of their order. This makes it easier to understand what each argument represents and is less prone to errors. You can specify them in any order.

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What are default arguments?

Default arguments provide a fallback value for a function parameter when no value is explicitly provided during function call. These arguments have a default value set at function definition which will be used if the caller does not provide the argument.

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What are variable-length arguments using *args?

A function can receive any number of arguments by using the *args syntax in the function definition. This captures all the arguments passed to the function and stores them in a tuple named 'args'.

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How do functions return values?

In Python, functions can return a value using the 'return' keyword. This value can then be used by the code that called the function. If no return statement is used, the function implicitly returns None.

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Study Notes

Python Programming - Unit II

  • This unit covers Python programming concepts, including flow control, loops, functions, and variable scope.

Flow of Control

  • Decision-making is crucial for controlling program flow.
  • Python uses conditional statements (if, if-else, nested if-else, if-elif-else) to execute code blocks based on conditions.
  • Indentation is critical for defining code blocks within conditional statements (using whitespace, generally 4 spaces).

Conditional Statements

  • if statement: Executes a block of code if a condition is true.
if condition:
    # code to execute if condition is true
  • if-else statement: Executes one block if a condition is true, another if it's false.
if condition:
    # code to execute if condition is true
else:
    # code to execute if condition is false
  • nested if: An if statement within another if statement.
if condition1:
    if condition2:
        # code to execute if both conditions are true
  • if-elif-else ladder: A series of conditions, where the first true condition's block is executed and the rest are skipped.
if condition1:
    # code to execute if condition1 is true
elif condition2:
    # code to execute if condition2 is true
else:
    # code to execute if neither condition is true

Loops

  • while loop: Repeatedly executes a block of code as long as a condition is true.
while condition:
    # code to execute while condition is true
  • for loop: Iterates over a sequence (like a list or string).
for item in sequence:
    # code to execute for each item
  • Python's range() function is used to generate sequences of numbers in for loops.
  • for-else loop: The else block executes if the loop completes normally (without a break).
for item in sequence:
    # code to execute for each item
else:
    # code to execute if the loop finishes without a break

Break, Continue, and Pass Statements

  • break: Exits the loop prematurely, skipping the remaining iterations.
  • continue: Skips the remaining code in the current iteration and proceeds to the next.
  • pass: A null statement; does nothing (used as a placeholder).

Functions

  • Functions organize code into reusable modules.
  • Syntax:
def function_name(parameters):
  """Docstring (optional): Describes function's purpose"""
  # Function body (code inside)
  return [expression]
  • Function call: Invokes a function.
  • Pass by reference: Modifying a list inside a function also alters the original list.
  • Return statement: Returns a value from a function (optional).
  • Types of Arguments:
    • Required arguments are mandatory and must have values supplied during a function call.
    • Keyword arguments are specified with variable name and values during the function.
    • Default arguments have a value specified during the definition.
    • Variable-length arguments accept any number of arguments.

Scope of Variables

  • Local variables: Defined within a function and only accessible inside that function.
  • Global variables: Defined outside any function and accessible throughout the program.

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