Question

Given variables one, two, and three, write an assertion for each of the following questions. a. Is one greater than both two and three? b. Is one greater than two, but less than three? c. Are all three variables greater than zero? d. Is one less than two or is one less than three? e. Is two greater than one and is three less than two?

Short answer

To assert each condition, use boolean checks combining logical operators with comparison signs.

Step-by-step solution

Understand Assertions

An assertion is a statement that checks whether a condition is true or false in a program. If the condition is true, the program continues; if false, it will raise an error. Each assertion checks a specific condition for the given variables: one, two, and three.

Assertion for a) Condition

For the condition "Is one greater than both two and three?", the assertion should verify if both these conditions are true: one > two and one > three. Therefore, the assertion will be: ``` assert one > two and one > three ```

Assertion for b) Condition

For the condition "Is one greater than two, but less than three?", the assertion should verify one > two and one < three. Thus, the assertion will be: ``` assert one > two and one < three ```

Assertion for c) Condition

To check if all three variables are greater than zero, the assertion must confirm one > 0, two > 0, and three > 0. The assertion is: ``` assert one > 0 and two > 0 and three > 0 ```

Assertion for d) Condition

For the condition "Is one less than two or is one less than three?", the assertion should verify if either one < two or one < three is true. The assertion is: ``` assert one < two or one < three ```

Assertion for e) Condition

To check if two is greater than one and three is less than two, the assertion must confirm two > one and three < two. The assertion is: ``` assert two > one and three < two ```

Key concepts

Conditional Statements

Conditional statements are the foundation of making decisions in programming. They help determine which block of code should be executed based on whether a condition is true or false. These statements are often structured using `if`, `elif`, and `else` clauses.

A simple example of a conditional statement might check if a number is greater than zero:

• If the number is greater than zero, print a message saying it's a positive number.
• If not, print a different message.

In our exercise, conditional statements are the basis for assertions, which verify whether a condition is met. For instance, checking if a variable called `one` is greater than `two` uses a conditional logic to verify that the statement holds true.

Logical Operators

Logical operators are used to combine conditional statements and to build more complex logic. The most common logical operators used in programming are `and`, `or`, and `not`.

• The `and` operator requires both conditions to be true.
• The `or` operator requires at least one of the conditions to be true.
• The `not` operator inverts the truth value of a condition.

In the context of the original exercise, the `and` operator was used to ensure that both conditions had to be true for an assertion to pass. For example, `assert one > two and one > three` only passes if `one` is indeed greater than both `two` and `three` simultaneously. Similarly, the `or` operator was used to check if `one` was less than either `two` or `three`.

Variable Comparison

Variable comparison involves checking relationships between different variables, using operators such as greater than `>`, less than `<`, equal to `==`, and not equal to `!=`. Comparisons are essential for analyzing data and making decisions based on certain criteria.

For example, determining whether `one` is greater than `two` can be straightforwardly checked using `assert one > two`. In the exercise, different comparisons between three variables were used to create assertions, such as checking whether all variables were greater than zero with `assert one > 0 and two > 0 and three > 0`. This step verifies that each variable meets the necessary criteria for the program logic to hold true.

Error Handling

Error handling is crucial in ensuring that a program can gracefully manage unexpected conditions and continue to function correctly. When an assertion fails in programming, it raises an error, indicating that the expected condition was not met.

In the context of the exercise, when an assertion does not hold true, the program will produce an error message. This message can help the programmer identify which assertion failed and why. Thus, error handling through assertions provides a valuable mechanism to validate assumptions.

• If a program continues to run without errors, it indicates that all assertions have been correctly met.
• If an error occurs, it acts as a clear signal that a certain condition has not been fulfilled, prompting a review of the logic.

Advanced error handling might also include using try-except blocks to catch and manage errors gracefully, ensuring that the program doesn't crash unexpectedly.