C++ string literals: select the single option that is an invalid string constant (i.e., not a valid string literal) while others are valid strings.
Computer Science
Object Oriented Programming Using C++
Difficulty: Easy
Choose an option
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A"Hello, world!"
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B"7.15 pm"
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C'multi char'
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D"i like e"
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E"1234e12"
Answer
Correct Answer: 'multi char'
Explanation
Introduction / Context:In C and C++, a string constant (string literal) is a sequence of characters enclosed in double quotes. It produces an array of characters terminated by a null character. This question asks you to identify which presented token is not a valid string literal, ensuring clarity about the difference between character and string constants.
Given Data / Assumptions:
- Valid string literals use double quotes, for example, "text".
- Character literals use single quotes and represent a single code unit (e.g., 'A').
- Options include both quoted forms and content with digits and spaces.
Concept / Approach:
- Anything in double quotes is a string literal, regardless of its textual content (digits, words, spaces).
- Single quotes denote a character literal; more than one character between single quotes is not a string literal and is invalid as a character literal in strictly conforming code (multi-character literals are implementation-defined integer constants, not strings).
- Therefore, an entry surrounded by single quotes containing multiple characters is not a valid string constant.
Step-by-Step Solution:
Inspect option A: "Hello, world!" → valid string literal.Option B: "7.15 pm" → valid string literal with digits, dot, and space.Option C: 'multi char' → uses single quotes and multiple characters → not a string literal; not a standard single character literal either.Option D: "i like e" → valid string literal.Option E: "1234e12" → still a string literal; numeric-like content does not change the type.Verification / Alternative check:
Compile-time types: options A, B, D, E have type const char[N]; option C would be an implementation-defined multi-character literal of type int (not a string), or rejected under strict rules, hence invalid as a string constant.Why Other Options Are Wrong:
- "Hello, world!", "7.15 pm", "i like e", "1234e12": All are proper string literals because they use double quotes.
Common Pitfalls:
- Confusing the lexical form (single vs double quotes) and assuming content determines type.
- Misusing single quotes for words; only double quotes produce strings.
Final Answer:
'multi char'