CMDP2063 Unix and C Programming (Revision)

What does the fopen() function do when opening a file in "r" mode?

• Opens a file for both reading and writing

• Opens a file for appending data to it

• Opens a file for reading only

• Creates a new file for writing

Answer explanation

The "r" mode in fopen() opens the file for reading only

What is the primary difference between printf() and fprintf() in C?

• fprintf() is used for reading input from a file, while printf() writes to a file.

• fprintf() is used for file output, while printf() is used for console output.

• fprintf() is slower than printf() because it works with larger files.

• fprintf() writes output to the console, while printf() writes to files.

Which of the following is the correct use of fgets() to read a line of text from a file?

• fgets(str, INPUT_SIZE, f);

• fgets(str, INPUT_SIZE, "input.txt");

• fgets(str, 100, "file.txt");

• fgets("text.txt", 100, str);

Answer explanation

The correct syntax for fgets() is fgets(str, INPUT_SIZE, f); where str is the array to store the text, INPUT_SIZE is the size of the buffer, and f is the pointer to the file.

In the following code, which of the following is the correct way to access the month field of the nested struct?

• answer.month;

• answer->date.month;

• answer[0].month;

• answer.date.month;

After allocating memory for a struct named door with malloc(), which function should be used to deallocate the memory?

• delete(door);

• free(door);

• destroy(door);

• deallocate(door);

Which of the following is a valid initialization of a Result struct?

• Result res = {75, "B"};

• Result res = {'B', 75};

• Result res = {75, 'B'};

• Result res = {grade = 'B', mark = 75};

What is the primary purpose of a debugger?

• To automatically fix errors in code

• To compile and run code more efficiently.

• To optimize code performance.

• To help debug software by allowing users to inspect and control a running program.

How can you add the -g flag in a Makefile to include debugging information during compilation?

• CFLAGS = -Wall -pedantic -ansi -g

• CFLAGS = -debug

• CFLAGS = -g

• CFLAGS = -O2

Answer explanation

You can add -g to the CFLAGS variable in a Makefile along with other flags like -Wall -pedantic -ansi to enable debugging information during compilation.

What does the file permission rwxr-x--- imply for "everyone else"?

• They have read and execute permissions.

• They have no permissions.

• They have read-only permissions.

• They have write and execute permissions.

Answer explanation

"Everyone else" (other users) has no permissions at all on the file, as indicated by the --- part of the permissions.

Which of the following is the primary purpose of the -l switch in the ls command?

• To display detailed information about files, including permissions, ownership, and type

• To list files in reverse order

• To show hidden files only

• To list files in alphabetical order