Which scenario would be most problematic when using fprintf() for data that needs exact binary preservation?

The correct answer is D: Both A and C are correct. fprintf() is text-oriented and interprets format specifiers, potentially modifying data. It also stops at NULL characters. For binary data, fwrite() is appropriate.

What is the risk in this code? char *str = malloc(5); strcpy(str, "Hello World");

The correct answer is D: Both A and B. Buffer overflow occurs (11 chars into 5 bytes), and memory is never freed, causing a leak.

In C, how many parameters can a function have at maximum?

The correct answer is C: No predefined limit in C standard. The C standard does not impose a maximum limit on the number of function parameters, though practical implementations may have compiler-specific limits.

What does the 'const' keyword do when applied to a pointer?

The correct answer is C: Can make either or both constant depending on placement. 'const int *ptr' makes the data constant, 'int * const ptr' makes the pointer constant, and 'const int * const ptr' makes both constant.

What is the primary purpose of the C preprocessor?

The correct answer is A: To process source code before compilation and perform text substitutions. The preprocessor is a text processing tool that processes source code before actual compilation, handling directives like #define, #include, and macros.

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C Programming

C language from basics to advanced placement prep

490 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 201–210 of 490

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.201 Medium Pointers

In pointer to function declaration: int (*ptr)(int, int); which statement is correct?

A ptr is a function returning pointer to int

B ptr is a pointer to a function taking two ints and returning int

C ptr is an array of function pointers

D ptr cannot be used to call functions

Correct Answer: B. ptr is a pointer to a function taking two ints and returning int

EXPLANATION

The parentheses around *ptr indicate ptr is a pointer. It points to a function that takes two int parameters and returns an int.

Test

Q.202 Medium Pointers

What will be the output?
int arr[5] = {1,2,3,4,5};
int *p = arr;
p += 2;
printf("%d", *p);

A 1

B 2

C 3

D Garbage value

Correct Answer: C. 3

EXPLANATION

p points to arr[0]. After p += 2, p points to arr[2] which contains value 3. Pointer arithmetic moves by element size.

Test

Q.203 Medium Pointers

Which of the following is a valid pointer comparison in C?

A if(p1 > p2 && p1 < p3) where p1, p2, p3 are unrelated pointers

B if(ptr == NULL) to check if pointer is null

C if(p1 == 5) where p1 is a pointer

D if(p1 - p2 > 10) where p1 and p2 point to different arrays

Correct Answer: B. if(ptr == NULL) to check if pointer is null

EXPLANATION

Comparing pointers with NULL is valid. Comparing unrelated pointers or subtracting pointers from different arrays is undefined behavior.

Test

Q.204 Medium Pointers

For dynamic 2D array allocation using int **arr = (int**)malloc(n*sizeof(int*)); what must be done next?

A Directly assign values to arr[i][j]

B Allocate memory for each row using a loop

C Call free() immediately

D Call realloc() for memory expansion

Correct Answer: B. Allocate memory for each row using a loop

EXPLANATION

After allocating memory for pointers, each pointer (row) must be allocated memory individually in a loop before accessing arr[i][j].

Test

Q.205 Medium Pointers

In: int *p; *p = 10; What is the issue?

A Syntax error

B p is uninitialized (wild pointer)

C Memory leak

D Type mismatch

Correct Answer: B. p is uninitialized (wild pointer)

EXPLANATION

p is not initialized to valid address. Dereferencing causes undefined behavior (writing to random memory location).

Test

Q.206 Medium Pointers

Which of the following is valid pointer comparison?

A p > 5

B p == q (different types)

C p < q (valid pointers)

D p + 10

Correct Answer: C. p < q (valid pointers)

EXPLANATION

Pointers of same type can be compared using <, >, ==, !=. Comparing with integers or different types is invalid.

Test

Q.207 Medium Pointers

For function: void modify(int *x) { *x = 20; } If called as modify(&a), what changes?

A The pointer itself

B The value of variable a

C The function parameter

D Nothing

Correct Answer: B. The value of variable a

EXPLANATION

Passing address allows function to modify original variable. *x = 20 changes the value at that address.

Test

Q.208 Medium Pointers

Which scenario demonstrates a dangling pointer?

A Pointer declared but not initialized

B Pointer freed but still used afterward

C Pointer set to NULL

D Pointer pointing to static variable

Correct Answer: B. Pointer freed but still used afterward

EXPLANATION

Dangling pointer occurs when memory is freed but pointer still references that location. This causes undefined behavior.

Test

Q.209 Medium Pointers

What is the purpose of the const keyword in: int * const p;?

A Pointer points to constant data

B Pointer itself is constant

C Both pointer and data are constant

D Data becomes read-only

Correct Answer: B. Pointer itself is constant

EXPLANATION

const after * means the pointer address cannot change, but the data it points to can be modified.

Test

Q.210 Medium Pointers

In the expression: int arr[5]; int *p = arr; What does p + 2 represent?

A Address of arr[0] + 2 bytes

B Address of arr[2]

C Value 2

D Address of arr[0] + 8 bytes

Correct Answer: B. Address of arr[2]

EXPLANATION

Pointer arithmetic scales by data type size. p + 2 moves 2 * sizeof(int) bytes forward, pointing to arr[2].

Test

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