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Core Python / Data: Types, Values, Variables, and Names

Core Python / Data: Types, Values, Variables, and Names#

  1. For each of the following literal values, what is the corresponding type?

    1. 1000: int
    2. -42: int
    3. 4.2: float
    4. 'a': str
    5. "alpha": str
    Note: Python does not contain a data type to represent a single character

  2. Explain the naming rules for variables.

    As you name a variable, you should create names that represent the purpose of that variable. The variable name must also follow these rules:

    • can only contain lowercase letters (a-z), uppercase letters (A-Z), digits (0-9), and an underscore(_)

    • cannot begin with a digit

    • cannot be one of Python’s reserved keywords.

    Variable names are case-sensitive.

  3. What guidelines should you follow in naming variables?

    Use informative names for variables to assist yourself and others in reading your code.

  4. What do all objects contain?

    • All objects maintain some sort of state - the data they object tracks. If there is no state present, then its really just a collection of functions.

    • Objects all have behavior - what functions/messages can be called. Without behavior, an object is simply a data structure.

    • Objects all contain an identity - something to uniquely distinguish an object. The identity may be part of an object’s state, but can also be just a reference or an interpreter-determined unique ID.

  5. What built-in function displays the value of variables or literals on the screen (console)?

    print

  6. Within the Python interpreter, how can we get more information about a particular keyword?

    Use the built-in function, help. Pass the keyword name as an argument to help().

  7. In Python, how does a variable determine its type? Can this type ever change?

    The interpreter automatically determines the type of a variable based on the result of an expression on the right-hand side of an assignment state.

    As Python is a dynamically typed language, the type associated with each variable can change based on the result of the right-hand expression in an assignment statement.

  8. Are variable names case-sensitive?

    Yes, variables are case-sensitive. However, you should avoid using variables that only differ in case. Avoiding similar names is also a good practice. Confusion only leads to problems.