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 string variable contains a numeric digit and displays "Digit" if it does, or "No digit" if it doesn't. Answer: ```python if ch.isdigit(): print("Digit") else: print("No digit.") ```

Step-by-step solution

Check if the character is a digit

To check if the character is a digit, you can use the isdigit() method. This method returns True if the string contains a digit and False otherwise. Use this method inside the if statement as follows: ```python if ch.isdigit(): ```

Display "Digit" if the character is a digit

If the isdigit() method returns True, then display "Digit". Use the print() function to display the message: ```python print("Digit") ```

Display "No digit" if the character is not a digit

If the isdigit() method returns False, then display "No digit". Use the else keyword and the print() function to display the message: ```python else: print("No digit.") ```

Complete code

Combining all the steps, the complete code for the if statement would look like this: ```python if ch.isdigit(): print("Digit") else: print("No digit.") ```

Key concepts

isdigit method

Understanding the isdigit method in Python can be incredibly helpful when working with text data. It's a built-in string method that helps determine if all the characters in a string are numeric digits. A digit in this context refers to any character from 0 to 9.

Here's how you use it:

single_char = '5'is_digit = single_char.isdigit()print(is_digit) # This would print True as '5' is a digit.

Using isdigit(), Python quickly checks each character to see if it qualifies as a numeric digit. If your string, stored in a variable like ch, is '7', 'ch.isdigit()' would return True. On the contrary, if ch is 'a' or '!', it would return False. It's a straightforward and efficient way to validate user input or process text data.

string methods

Strings in Python come with a variety of built-in methods that make it easy to perform common tasks. The isdigit method is just one of many such helpful tools. Other common string methods include isalpha() to check if a string contains only letters, and isspace() to check for whitespace characters.

Consider the following examples to get a better understanding:

• my_string.isalpha() - Returns True if all characters in the string are alphabetic.
• my_string.isalnum() - Checks if the string has at least one character and all characters are alphanumeric.
• my_string.strip() - Removes whitespace from both ends of the string.

These methods are invaluable for data cleaning and validation, as they provide quick checks and transformations on string data without the need for complicated loops or conditional logic.

conditional statements in Python

In Python, conditional statements, also known as if statements, are a fundamental aspect of controlling the flow of a program. They allow you to execute certain pieces of code based on whether a condition is true or not.

Here's a simple structure:

if condition:    # Code to execute if the condition is trueelse:    # Code to execute if the condition is false

For example: To decide if we display 'Digit' or 'No digit' based on the contents of a variable, the conditional statement checks the result of the isdigit() method.

The power of if statements isn't limited to binary choices either. You can add elif clauses to handle multiple conditions, allowing for complex decision-making within your programs.
The beauty of conditional statements in Python is their readability. They almost read like English, making your code intuitive to understand and maintain.