ReactCHALLENGES

6. Default values

A parameter can have a default value. Write it as parameter=value in the definition. If the caller omits that argument, Python uses the default:

  • base has no default, so it is required.
  • exponent=2 is optional; when omitted, exponent is 2.
  • Parameters with defaults must come after parameters without defaults.
  • An explicit argument always overrides the default.

Coming from JavaScript? Defaults are evaluated once, when the function is defined, not on every call. Never use a mutable default such as items=[]; use None and create the list inside the function.

#01

Use a default value

Define greet(name="world") that prints Hello, world! when called with no arguments. Call greet().

Print exactly:

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#02

Override the default

Define greet(name="world") that prints Hello, <name>!. Call it with the argument "Ada". The explicit argument replaces the default.

Print exactly:

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#03

A default in a calculation

Define power(base, exponent=2) that returns base ** exponent. Print power(3). With only one argument, exponent keeps its default value 2.

Print exactly:

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#04

Compare default and explicit arguments

Define power(base, exponent=2) as above. Print power(3), then print power(2, 5). The first call uses the default; the second overrides it.

Print exactly:

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