Question

$$ \begin{aligned} &\text { What do these code fragments print? }\\\ &\text { a. } \begin{aligned} n &=1 \\ m &=-1 \\ \text { if } n &<-m: \\ \text { print }(n) & \\ \text { else : } & \\ & \text { print (n) } \end{aligned} \end{aligned} $$

Short answer

The code prints 1.

Step-by-step solution

Understand the Initial Values

We start with two integer variables, \( n \) and \( m \). Initially, \( n = 1 \) and \( m = -1 \).

Evaluate the Condition

The condition given is \( n < -m \). Substituting the values, the inequality becomes \( 1 < -(-1) \), which simplifies to \( 1 < 1 \). This condition is false.

Execute the Else Branch

Since the condition \( n < -m \) is false, we follow the 'else' branch of the code, which executes \( \text{print}(n) \). Therefore, the printed value is the current value of \( n \), which is \( 1 \).

Key concepts

Python programming

Python is a popular programming language known for its simplicity and readability. This language is flexible, allowing programmers to write code that is clear and efficient. One of the defining features of Python is its use of indentation to define the blocks of code, which enhances clarity.

Python is widely used for web development, data analysis, artificial intelligence, and scientific computing. It supports multiple programming paradigms such as procedural, object-oriented, and functional programming.

• High-level language: Python is user-friendly and abstracts complex details, allowing programmers to focus on coding.
• Interpreted language: Python code is executed line-by-line rather than compiled all at once, making debugging easier.
• Rich libraries: Python comes with a vast number of libraries, such as NumPy and Pandas, which simplify complex tasks.

Its simple syntax ensures that newbies can pick up the basics with ease, making Python an excellent choice for beginners.

control structures

Control structures in Python dictate the flow of execution within a program. They allow your program to make decisions, repeat tasks, and control the execution path based on conditions.

These control structures are crucial as they enable you to write dynamic and interactive programs. Common control structures in Python include:

• Conditional statements: Decisions based on conditions, implemented using if, elif, and else.
• Loops: Repeating a block of code multiple times, using structures like for and while loops.

By using these control structures, a programmer can:

• Direct the program flow with decision-making capabilities.
• Automate repetitive tasks efficiently.
• Create sophisticated algorithms with multiple execution paths based on different conditions.

Mastering control structures in Python is essential for writing efficient and effective code.

if-else decision making

The if-else decision-making structure in Python allows you to execute certain code based on whether a condition is true or false. This structure is foundational in making programs that can adaptively respond to variables and inputs.

The basic structure follows this pattern:```if condition: # code to execute if condition is trueelse: # code to execute if condition is false```This feature helps programmers manage the control flow more dynamically within the application.

Consider the example from the exercise, where the condition is evaluated using "if":

• If the condition \( n < -m \) is true, the program would execute the code inside the "if" block.
• If false, as in the exercise, the program skips to "else" block and prints the value of \( n \).

Understanding the if-else logic is vital for any conditional execution in Python and is a key element in control structures.

logical expressions

Logical expressions are used in Python to make decisions based on multiple conditions. They involve operators such as and, or, and not, which combine and evaluate Boolean expressions.

The logic operators include:

• and: Returns True if both operands are true.
• or: Returns True if at least one operand is true.
• not: Reverses the truth value of the operand.

Logical expressions help in forming complex conditions by combining simpler ones, enhancing decision making.

In the original exercise, the expression \( n < -m \) is a simple form of logical expression. Even though this example doesn't use logical operators, more complex conditions would include them, allowing checks across multiple variables.

These expressions are crucial for evaluating conditions within control structures, making your code more versatile and robust.