What will be the preprocessed output of the following code? #define SQUARE(x) x*x int result = SQUARE(5+3);

The correct answer is C: 5+3*5+3 = 23. Without parentheses, SQUARE(5+3) expands to 5+3*5+3, which evaluates to 5+15+3=23 due to operator precedence, not (5+3)*(5+3)=64. This demonstrates why macro parameters need parentheses.

What is the difference between declaring a function and defining a function?

The correct answer is A: Declaration specifies the function signature; definition includes the function body. A declaration tells the compiler about the function's signature (return type, name, parameters); a definition provides the actual implementation (function body).

What is the difference between 'const int *p' and 'int * const p'?

The correct answer is C: First prevents changing value, second prevents changing pointer. 'const int *p' - pointer can change but value cannot. 'int * const p' - value can change but pointer cannot.

Consider the code: int x = 10; int *p = &x; int **q = &p; What is the value of **q?

The correct answer is A: 10. q points to p, p points to x. **q dereferences twice: first gets p's value (address of x), second gets x's value (10).

Consider: void func(int *p); Which statement is correct about this function declaration?

The correct answer is B: func takes a pointer to integer as parameter. The * in the parameter declaration indicates that func takes a pointer to an integer, not an integer value.

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C Programming
File Handling

C language from basics to advanced placement prep

27 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 21–27 of 27

Topics in C Programming

All Basics & Syntax 86 Data Types & Variables 97 Control Flow 100 Functions 99 Arrays & Strings 100 Pointers 99 Structures & Unions 100 File Handling 100 Dynamic Memory 98 Preprocessor 99

Q.21 Easy File Handling

In file handling, what does the 'b' flag in file modes like 'rb' or 'wb' indicate?

A Binary mode operation

B Buffered mode operation

C Bidirectional mode operation

D Backup mode operation

Correct Answer: A. Binary mode operation

EXPLANATION

The 'b' flag specifies binary mode, which prevents any translation of line endings or special characters.

Test

Q.22 Easy File Handling

Which of the following file modes in fopen() allows reading only?

A "w"

B "r"

C "a"

D "w+"

Correct Answer: B. "r"

EXPLANATION

The 'r' mode opens a file for reading only. The file must exist, otherwise fopen() returns NULL.

Test

Q.23 Easy File Handling

When opening a file in 'w' mode, what happens if the file already exists?

A The file is truncated and all previous content is deleted

B The file is opened in append mode automatically

C An error is returned and file is not opened

D The file pointer is positioned at the end

Correct Answer: A. The file is truncated and all previous content is deleted

EXPLANATION

Opening a file in 'w' mode truncates the file to zero length if it exists, discarding all previous content.

Test

Q.24 Easy File Handling

Which mode opens a file for writing and truncates it if it exists?

A "w"

B "a"

C "r+"

D "w+"

Correct Answer: A. "w"

EXPLANATION

"w" mode opens a file for writing. If the file exists, it truncates the file to zero length. If it doesn't exist, a new file is created.

Test

Q.25 Easy File Handling

Which function is used to close a file in C?

A fclose()

B close_file()

C file_close()

D closefile()

Correct Answer: A. fclose()

EXPLANATION

fclose() is the standard function to close an opened file stream. It returns 0 on success and EOF on error.

Test

Q.26 Easy File Handling

What does the mode 'rb' mean in fopen()?

A Read in binary mode

B Read and backup mode

C Rewrite and binary mode

D Remove and backup mode

Correct Answer: A. Read in binary mode

EXPLANATION

'rb' mode opens a file for reading in binary format. Binary mode reads the exact bytes without any text conversion.

Test

Q.27 Easy File Handling

Which function is used to open a file in C?

A fopen()

B open_file()

C file_open()

D openfile()

Correct Answer: A. fopen()

EXPLANATION

fopen() is the standard C library function used to open a file. It takes two arguments: filename and mode.

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