Question

Write an if statement that displays "Digit" if the string referenced by the variable ch contains a numeric digit. Otherwise, it should display "No digit."

Short answer

Question: Write an if statement that checks if a given variable, ch, contains a numeric digit or not. If it does, the program should display "Digit", otherwise it should display "No digit." Answer: To check if a variable `ch` contains a numeric digit, you can use the Python `isdigit()` method. The if statement would look like this: ``` if ch.isdigit(): print("Digit") else: print("No digit") ```

Step-by-step solution

Check if ch contains a numeric digit

To check if a variable "ch" contains a numeric digit, we can use the isdigit() method which is a pre-built function in Python. The isdigit() method returns True if the string contains a digit and False otherwise.

Write the if statement

Now that we have a method to check if ch contains a numeric digit, we can use this to create the if statement. If isdigit() returns True, we display "Digit", and if it returns False, we display "No digit." Here is the code based on the previous analysis: """ ch = "5" if ch.isdigit(): print("Digit") else: print("No digit") """

Key concepts

if statement

The `if statement` is a fundamental concept in Python programming used to make decisions based on specific conditions. It allows the program to execute certain blocks of code only if a given condition evaluates to true. This mechanism helps create dynamic and responsive programs.

An `if statement` begins with the `if` keyword, followed by a condition, and a colon. The block of code intended for execution is indented under the `if` statement. If the condition evaluates to `True`, Python executes this block; if it's `False`, Python skips to the next statement. You can also add `else` to specify what should happen if the condition is `False`.

• Start your condition with the `if` keyword.
• Ensure your conditions return a boolean value: `True` or `False`.
• Indent your code block within the `if` statement.

Combining `if` with `else` allows more complex decision paths.

string methods

Python offers a variety of string methods that perform different operations on strings. They make it easier to manipulate and examine text elements in your programs.

One useful method is `isdigit()`, which checks if all characters in a string are digits. Here's how it works:

• When `isdigit()` is called on a string, it returns `True` if all characters are digits (0-9).
• If the string contains any non-digit characters, `isdigit()` returns `False`.

For example, the code snippet `ch.isdigit()` checks whether the variable `ch` is composed entirely of digits. This method is a quick and efficient way to validate numeric inputs.

Learning and using string methods can greatly simplify text processing tasks in Python.

conditional logic

Conditional logic is about making decisions in programming. It uses expressions that evaluate to either `True` or `False`. These expressions decide which code blocks get executed.

The `if statement` is a basic form, but other structures extend conditional logic in Python:

• `else` allows you to run code if the `if` condition is `False`.
• `elif` lets you check multiple conditions in sequence, acting as an `else if`.

By combining these elements, you can test various scenarios and execute different code paths, making your programs adapt to a variety of situations.

For example, using the `isdigit()` method in a condition is a form of conditional logic. If the method returns `True`, one set of instructions runs; if `False`, another set does. Understanding and mastering conditional logic unlocks powerful capabilities in Python programming, enabling you to manage complex decision-making processes efficiently.