What is the expected output of the following code? x = '\'' print(len(x))

The code initializes a string variable x with the literal '\''. In Python, the backslash (\) acts as an escape character, which modifies the interpretation of the character that follows it. The sequence \' is an escape sequence that represents a single character: the single quote ('). Consequently, the variable x contains a string of length one. The len() function is called with x as its argument, and it returns the number of characters in the string, which is 1. This value is then printed to the standard output.

B: The escape sequence \' is interpreted by the Python interpreter as a single character, not as two separate characters (a backslash and a quote).

C: The code is syntactically correct. Using an escape sequence to include a special character like a single quote within a single-quoted string is a valid and standard practice in Python.

D: The string is not empty; it contains exactly one character (the single quote). Therefore, its length is 1, not 0.

1. The Python Language Reference (Official Vendor Documentation):

Section 2.4.1, "String and Bytes literals". The table of recognized escape sequences explicitly lists \' as the sequence for a single quote character ('). This confirms that '\'' is a string literal representing one character.

Available at: https://docs.python.org/3/reference/lexicalanalysis.html#string-and-bytes-literals

2. The Python Standard Library Documentation (Official Vendor Documentation):

Section "Built-in Functions", len(s). The documentation states that len() returns "the length (the number of items) of an object." For a string, this means the number of characters.

Available at: https://docs.python.org/3/library/functions.html#len

3. MIT OpenCourseWare (University Courseware):

Course 6.0001, "Introduction to Computer Science and Programming in Python", Fall 2016. Lecture 3 notes discuss strings and the len() function. It is explained that len() returns the number of characters in a string and that escape sequences like \n or \' count as a single character.

Reference Material: Lecture 3 notes, page 2. Available at: https://ocw.mit.edu/courses/6-0001-introduction-to-computer-science-and-programming-in-python-fall-2016/resources/mit60001f16lec3/