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Questions and Answers
Which of the following is NOT a valid identifier in Python?
Which of the following is NOT a valid identifier in Python?
What is the purpose of indentation in Python?
What is the purpose of indentation in Python?
Which of the following is a valid way to declare a variable in Python?
Which of the following is a valid way to declare a variable in Python?
What happens if you try to use a reserved word as a variable name in Python?
What happens if you try to use a reserved word as a variable name in Python?
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Which of the following is a valid way to declare and assign multiple variables in Python?
Which of the following is a valid way to declare and assign multiple variables in Python?
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What is the result of the following code?
x = 5
y = x
x = 10
print(y)
What is the result of the following code? x = 5 y = x x = 10 print(y)
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Which of the following is a valid way to declare a constant in Python?
Which of the following is a valid way to declare a constant in Python?
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What is the result of the following code?
x = 'hello'
y = x
x += ' world'
print(y)
What is the result of the following code? x = 'hello' y = x x += ' world' print(y)
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Which of the following is a valid way to declare a list in Python?
Which of the following is a valid way to declare a list in Python?
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What is the result of the following code?
x = 10
y = x
x = 20
print(x, y)
What is the result of the following code? x = 10 y = x x = 20 print(x, y)
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Study Notes
Identifiers
- An identifier is a collection of alphanumeric characters used to give names to programming elements like variables, arrays, and functions.
- Rules for constructing identifiers:
- Start with an alphabet or underscore
- Followed by any number of alphabets, digits, or underscores
- Cannot start with a digit
- Unique name given to a program element
- Case sensitive, so 'max' and 'MAX' are considered different identifiers
- Cannot contain special symbols, commas, or blank spaces
- Should not be the same as keywords, otherwise, the compiler will generate an error
Variables
- Variables are parts of computer memory where information is stored.
- Each variable is given an appropriate name to identify the memory location easily.
- A variable can be defined as a reserved memory location that stores values.
- Rules for variables:
- Can only have alphanumeric characters (a-z, A-Z, 0-9) and underscore (_)
- First character can only be an alphabet (a-z, A-Z) or underscore (_)
- Keywords cannot be used as variable names
- No special characters are permitted to be used in or as identifiers
- Variables are case sensitive
Data Types in Python
- Numbers:
- Int: Integer numbers, can be positive or negative, have unlimited built-in size
- Float: Floating-point numbers, written as decimal numbers separated by a decimal point
- Complex: Defined as complex class in Python
- Escape Sequences in Python:
- \: Print a backslash
- ': Print a single quote
- ": Print a double quote
- \a: Rings a bell
- \n: Print a newline
- \t: Print a tab
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Description
Test your knowledge on Python identifiers by answering questions about their definition and rules for construction. Identify different variable names and understand the concept of identifiers in programming.
