What does the restrict keyword do when used with pointer parameters in C99?

The correct answer is B: Tells compiler that pointer is not aliased, enabling optimizations. The restrict keyword (C99) is a promise to the compiler that the pointer is the only way to access that memory during its lifetime, allowing aggressive optimizations.

In a string comparison, strcmp('Apple', 'apple') returns:

The correct answer is C: A non-zero positive value. strcmp() is case-sensitive. ASCII value of 'A' (65) is less than 'a' (97), so it returns negative value. But 'A' < 'a', so it returns -32 (negative).

What is the output? int arr[2][3] = {{1,2,3}, {4,5,6}}; int *p = (int*)arr; printf("%d", *(p+4));

The correct answer is A: 5. Array flattened: 1,2,3,4,5,6. p+4 points to 5th element which is 5.

Which of the following is valid pointer comparison?

The correct answer is C: p < q (valid pointers). Pointers of same type can be compared using , ==, !=. Comparing with integers or different types is invalid.

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C Programming

C language from basics to advanced placement prep

291 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 161–170 of 291

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.161 Easy Arrays & Strings

Which of the following correctly declares a 2D array of strings?

A char str[5][20];

B char *str[5];

C Both A and B are valid

D char str[5, 20];

Correct Answer: C. Both A and B are valid

EXPLANATION

Both are valid ways to declare arrays of strings. Option A creates a 2D array, Option B creates an array of pointers to strings.

Test

Q.162 Easy Arrays & Strings

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

A 4

B 3

C 5

D Compilation error

Correct Answer: A. 4

EXPLANATION

arr + 3 points to the 4th element (index 3) which is 4. Dereferencing gives 4.

Test

Q.163 Easy Arrays & Strings

What does strlen() function return for the string "C2025"?

A 5

B 6

C 4

D Undefined behavior

Correct Answer: A. 5

EXPLANATION

strlen() counts characters before the null terminator. "C2025" has 5 characters, so strlen returns 5. The null terminator is not counted.

Test

Q.164 Easy Arrays & Strings

What is the time complexity of accessing an element at index 5 in an array?

A O(1) - Constant time

B O(n) - Linear time

C O(log n) - Logarithmic time

D O(n²) - Quadratic time

Correct Answer: A. O(1) - Constant time

EXPLANATION

Array access by index is O(1) because arrays use contiguous memory allocation, allowing direct access via base address + offset calculation.

Test

Q.165 Easy Arrays & Strings

How much memory is allocated for char name[50] declaration?

A 50 bytes

B 49 bytes

C 51 bytes

D Depends on compiler

Correct Answer: A. 50 bytes

EXPLANATION

char name[50] allocates exactly 50 bytes. The null terminator '\0' must fit within this 50-byte allocation.

Test

Q.166 Easy Arrays & Strings

In C, a string is internally represented as:

A An array of characters terminated by '\0'

B An array of integers with length prefix

C A special data type with built-in length

D A pointer to the first character with separate length variable

Correct Answer: A. An array of characters terminated by '\0'

EXPLANATION

In C, strings are null-terminated character arrays. The null character '\0' marks the end of the string.

Test

Q.167 Easy Arrays & Strings

If an integer array arr[10] is declared globally in C, what will be the initial values of its elements?

A All elements initialized to 0

B All elements contain garbage values

C All elements initialized to 1

D Elements are uninitialized until explicitly set

Correct Answer: A. All elements initialized to 0

EXPLANATION

Global arrays in C are automatically initialized to 0 by default. Only local arrays contain garbage values.

Test

Q.168 Easy Arrays & Strings

Consider a 2D array declared as: int matrix[3][4]. How many elements does it have?

A 3

B 4

C 7

D 12

Correct Answer: D. 12

EXPLANATION

A 2D array with dimensions 3x4 has 3*4 = 12 total elements.

Test

Q.169 Easy Arrays & Strings

What does the following code do? strcpy(dest, src);

A Compares two strings

B Copies string src to dest

C Concatenates two strings

D Finds length of string

Correct Answer: B. Copies string src to dest

EXPLANATION

strcpy() copies the contents of the source string to the destination string.

Test

Q.170 Easy Arrays & Strings

Which of the following is NOT a valid string initialization?

A char str[] = "Program";

B char str[10] = {'P','r','o','g'};

C char str[10]; str = "Program";

D char *str = "Program";

Correct Answer: C. char str[10]; str = "Program";

EXPLANATION

Array names are constant pointers and cannot be reassigned. Direct assignment to char array after declaration is invalid.

Test

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