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2.3: Expressions and statements

  • Page ID
    40852
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    An expression is a combination of values, variables, and operators. A value all by itself is considered an expression, and so is a variable, so the following are all legal expressions:

    >>> 42
    42
    >>> n
    17
    >>> n + 25
    42
    

    When you type an expression at the prompt, the interpreter evaluates it, which means that it finds the value of the expression. In this example, n has the value 17 and n + 25 has the value 42.

    A statement is a unit of code that has an effect, like creating a variable or displaying a value.

    >>> n = 17
    >>> print(n)
    

    The first line is an assignment statement that gives a value to n. The second line is a print statement that displays the value of n.

    When you type a statement, the interpreter executes it, which means that it does whatever the statement says. In general, statements don’t have values.


    2.3: Expressions and statements is shared under a CC BY-NC 3.0 license and was authored, remixed, and/or curated by Allen B. Downey (Green Tea Press) .

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