Tutorialspoint的C模拟测试准确性及相关编译问题咨询

Hey there, let's unpack your questions one by one—having 20+ years of C experience means you’ve got a rock-solid foundation, so don’t let that test score throw you off!

Free online coding tests like this one are hit-or-miss, and Tutorialspoint’s C tests are no exception. Most aren’t written by experts who deeply understand modern C standards (like C11), so you’ll often find outdated questions, ambiguous wording, or even code that violates current standard rules. Your score here doesn’t reflect your actual 20+ years of expertise—trust your experience over this test.

The issue almost certainly lies with the test’s code, not you or your compiler. That gcc command enables strict compliance with the C11 standard, flagging any non-conforming code as an error. Many of Tutorialspoint’s test snippets are likely written for older standards (like C89) or rely on non-portable compiler extensions. Common reasons for failures include:

• Implicit function declarations (allowed in C89, banned in C11)
• Use of deprecated/removed functions (e.g., gets(), which was dropped in C11)
• Non-standard types or keywords (e.g., relying on GCC-specific extensions like __attribute__ without wrapping them in standard-compliant guards)
• Violations of type safety rules that older tests might ignore (e.g., mismatched printf format specifiers)

Since I don’t have the exact question text, I can speak to common patterns in these types of tests that align with your list:

• Q7/Q9/Q10: Often involve pointer arithmetic, array bounds, or implicit type conversions. For example, a test might present code with array out-of-bounds access (undefined behavior in C) and mark a wrong answer as "correct", or use implicit conversions that C11 treats as unsafe.
• Q14/Q16/Q17: Macro-related pitfalls are common here. Tests might use macros without proper parentheses (leading to unexpected evaluation) or non-standard string concatenation that gcc -pedantic-errors flags.
• Q19/Q21: Likely focus on function return types or storage classes. For instance, older tests might accept main() without an int return type (required in C11) or misuse the register keyword (which has stricter rules in modern C).
• Q27/Q28: Struct memory alignment or bitfield issues. Some tests use non-standard bitfield types (e.g., bitfields on long long) that aren’t fully defined by the C standard, leading to compiler errors under strict mode.
• Q31/Q32/Q33: Preprocessor quirks. Tests might use undefined macros in #if directives (undefined behavior in C11) or non-standard #pragma directives that gcc rejects.
• Q35/Q38: String handling with non-standard functions. For example, strdup() is a POSIX extension, not part of the C standard—-pedantic-errors will flag this as an error.
• Q46: Usually involves type conversion edge cases. Older tests might have incorrect assumptions about implicit conversions (e.g., float to int truncation) or misuse the _Bool type (introduced in C99/C11, which older tests might not handle correctly).

If you can share the exact code or wording of any of these questions, I can give you precise correct answers and explain the standard compliance issues in detail.

内容的提问来源于stack exchange，提问作者Lundin