Quiz for Error handling strerror

Q1: What does the strerror function do?

A. Returns a pointer to the error message string corresponding to an error number B. Prints an error message C. Sets the errno variable D. Clears an error

Q2: Which header file must be included to use strerror?

A. string.h B. errno.h C. stdio.h D. stdlib.h

Q3: What argument does strerror take?

A. An integer error number (errno) B. A string C. A pointer D. No argument

Q4: If strerror is called with an invalid error number, what happens?

A. Returns "Unknown error" B. Crashes the program C. Returns NULL D. Returns empty string

Q5: Is the string returned by strerror modifiable?

A. No, it should not be modified B. Yes, always safe to modify C. Depends on the platform D. Only if copied

Q6: What is the return type of strerror?

A. char * B. int C. void D. const char *

Q7: Which of the following is a correct usage of strerror?

A. printf("%s", strerror(errno)); B. strerror(errno, buf); C. char *msg = strerror(); D. strerror("errno");

Q8: Is strerror thread-safe?

A. Generally no, better to use strerror_r B. Yes C. Only on POSIX systems D. Depends on compiler

Q9: Which function is a thread-safe alternative to strerror?

A. strerror_r B. perror C. printf D. scanf

Q10: What happens if strerror is called repeatedly with the same errno?

A. Returns pointer to the same string B. Returns a new copy C. May crash D. Returns NULL

Q11: Can the pointer returned by strerror be used after a subsequent call to strerror?

A. No, it may be overwritten B. Yes, always safe C. Depends on platform D. Only if copied

Q12: Which errno value corresponds to "No such file or directory"?

A. ENOENT B. EINVAL C. ENOMEM D. EBADF

Q13: What should you do before calling strerror?

A. Ensure errno is set by a failing function B. Reset errno to zero C. Call perror D. Close files

Q14: Can strerror be used to print error messages directly?

A. No, it returns a string that must be printed B. Yes, it prints error messages C. Only on Windows D. Only in debug mode

Q15: Which of these is NOT a valid errno value?

A. 9999 B. ENOENT C. EINVAL D. ENOMEM

Q16: What is the purpose of errno in C?

A. To store the error code of the last function that failed B. To count errors C. To terminate the program D. To log errors

Q17: Which function sets errno?

A. fopen B. printf C. scanf D. strlen

Q18: Can strerror be used on Windows?

A. Yes, it is supported B. No, only on Unix C. Only in MinGW D. Only with special libraries

Q19: How to get the error string for error number 2?

A. strerror(2) B. perror(2) C. strerror_r(2) D. errno = 2;

Q20: Is the string returned by strerror localized?

A. Depends on implementation and locale B. Always English C. Never localized D. Depends on compiler