Quiz for Error handling perror

Q1: What does the perror function do in C?

A. Prints a descriptive error message to stderr B. Terminates the program C. Returns the error code D. Clears the error indicator

Q2: Which header file is required to use perror?

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

Q3: What argument does perror take?

A. A custom message string B. An error code C. An integer D. No argument

Q4: If you call perror("Error"), what is printed?

A. "Error: " followed by the error description B. "Error" only C. The error code D. Nothing

Q5: Does perror modify the value of errno?

A. No B. Yes C. Only on error D. Depends on system

Q6: Which of the following is true about perror?

A. It helps in debugging by printing error messages B. It clears error codes C. It terminates the program D. It resets errno

Q7: Which standard output stream does perror use?

A. stderr B. stdout C. stdin D. None

Q8: Which function is commonly called before perror to detect errors?

A. A function that sets errno, e.g., fopen B. printf C. malloc D. main

Q9: Is perror thread-safe in modern systems?

A. Generally yes, using thread-local errno B. No C. Only in single-threaded programs D. Depends on OS version

Q10: What happens if you call perror with NULL?

A. Prints only the error message B. Causes a crash C. Prints "null" D. No output

Q11: Which function complements perror for getting error messages as strings?

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

Q12: Can perror be used to print errors from system calls?

A. Yes B. No C. Only library functions D. Only application code

Q13: What type of argument does perror require?

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

Q14: Which of the following is a valid use of perror?

A. perror("File open error") B. perror(5) C. perror(NULL, "error") D. perror()

Q15: What is the output of perror("Error") if errno = ENOENT?

A. Error: No such file or directory B. Error: Permission denied C. Error: Invalid argument D. Error: Out of memory

Q16: Is it necessary to reset errno before calling perror?

A. No, but recommended to reset before function that may set it B. Yes C. Only in debug mode D. Depends on the compiler

Q17: Which of the following functions does NOT set errno?

A. printf B. fopen C. read D. write

Q18: Why is perror preferred over printf for error messages?

A. It automatically adds descriptive error text B. It is faster C. It writes to a file D. It changes errno

Q19: What happens if you pass an empty string "" to perror?

A. Prints just the error message B. Prints nothing C. Causes error D. Prints a newline only