PCAP - Certified Associate in Python Programming

The length of a string containing a space is greater than zero. The escape sequence for a single quote represents one character, so its string length is 1. The other expressions are false because character codes and case-sensitive comparisons do not produce the expected values.

A class statement must contain a syntactically valid suite. pass is a valid statement that deliberately performs no action, so class X: pass defines an otherwise empty class. A header with no suite is incomplete, return is not valid at class scope, and braces do not serve as an empty class body in Python.

For an ordinary instance method, Python supplies the object used for the method call as the first parameter. Conventionally named self, that parameter holds a reference to the currently processed object and allows access to its attributes and methods. It is determined by method binding, not by None or a random value.

Scientific notation multiplies the coefficient by 10 raised to the exponent. The literal .3423e2 evaluates to 0.3423 times 100, which is 34.23. The literal 3423e-2 evaluates to 3423 times 0.01, also 34.23. Reversing those exponent signs produces values with different decimal positions.

Each loop iteration prepends the current character to dummy, so the text representation of the fraction is reversed. The last character of that reversed string is consequently the first character of the original representation. That original representation begins with 0, so indexing dummy at its final position outputs 0.

Object is constructed as an instance of Lower, so isinstance(Object, Lower) evaluates to True. The Lower initializer explicitly calls super().__init__(), which runs Upper.__init__ and assigns 'upper' to the inherited instance property. The two prints consequently produce True upper.

get is an instance method, so show must access it through the current instance. In self.get(), Python binds self automatically and the method returns self.val. Passing that result to print displays the stored value. An unqualified get() is not resolved as another method of the instance.

A class's __bases__ attribute records its direct superclasses. Its value is a tuple containing the actual base class objects in the order used in the class declaration. Because it stores class objects rather than names, identifiers, or memory locations, it can be used directly for inheritance introspection, including examining each base class's own attributes.

The second argument of open() is optional because the default mode is "r" (read mode). The standard streams are named stdin, stdout, and stderr and are automatically opened by the operating system. The open() function returns a file object, not an integer file handle, and it raises an exception if opening the file fails instead of returning None.

open() attempts to establish access to a file, and a failure such as an unavailable path or disallowed mode raises an exception. On success, it returns a file object representing the opened file and providing operations such as read, write, and close. Its mode argument is optional because it defaults to reading; the standard stream names are stdin, stdout, and stderr.