Which allocation method is most suitable for a dynamically growing linked list?

The correct answer is B: malloc() for each node as needed. Each node should be allocated individually with malloc() to allow dynamic growth and efficient memory usage.

Which of the following is correct about static variables in C?

The correct answer is B: They retain their value between function calls. Static variables retain their value between function calls and are initialized only once. They persist for the lifetime of the program.

Consider a structure with bit fields: struct Flags { unsigned int flag1 : 1; unsigned int flag2 : 3; unsigned int flag3 : 4; }; What is the minimum size of this structure?

The correct answer is C: 4 bytes. Bit fields must fit within an underlying integer type. Total bits = 8, which requires at least 4 bytes (one int on most systems).

Which scenario demonstrates a dangling pointer?

The correct answer is B: Pointer freed but still used afterward. Dangling pointer occurs when memory is freed but pointer still references that location. This causes undefined behavior.

What is the correct syntax to open a file named 'data.txt' in read mode?

The correct answer is B: fopen("data.txt", "r"). fopen() uses double quotes for string arguments in C. The first argument is filename and second is mode. Single quotes are for characters, not strings.

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C Programming
Arrays & Strings

C language from basics to advanced placement prep

30 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 1–10 of 30

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.1 Easy Arrays & Strings

Consider the following code:

char str[] = "HELLO";
int len = 0;
while(str[len] != '\0') {
len++;
}
printf("%d", len);

What will be the output?

A 5

B 6

C 4

D Undefined behavior

Correct Answer: A. 5

EXPLANATION

The string "HELLO" has 5 characters. The while loop counts characters until it encounters the null terminator '\0'. The output will be 5. The null terminator is not counted in the length.

Test

Q.2 Easy Arrays & Strings

What will be the size in bytes of int arr[5] on a 32-bit system?

A 5 bytes

B 10 bytes

C 20 bytes

D Depends on compiler

Correct Answer: C. 20 bytes

EXPLANATION

On 32-bit systems, int is typically 4 bytes. 5 elements × 4 bytes = 20 bytes total.

Test

Q.3 Easy Arrays & Strings

What is the output of: int arr[] = {10, 20, 30}; printf("%d", *(arr+1));?

A 10

B 20

C 30

D Garbage value

Correct Answer: B. 20

EXPLANATION

arr+1 points to second element (arr[1]). Dereferencing gives value 20.

Test

Q.4 Easy Arrays & Strings

What is the correct way to declare and initialize a string in C?

A char str = "Hello";

B char *str = "Hello"; OR char str[] = "Hello";

C String str = "Hello";

D char str[10] = {"Hello"};

Correct Answer: B. char *str = "Hello"; OR char str[] = "Hello";

EXPLANATION

Option B shows two valid ways: pointer to string literal or character array. Option A is wrong (single char), C is wrong (no String type in C).

Test

Q.5 Easy Arrays & Strings

How many elements can be stored in a 2D array declared as int matrix[4][5]?

A 4 elements

B 5 elements

C 9 elements

D 20 elements

Correct Answer: D. 20 elements

EXPLANATION

A 2D array with dimensions [4][5] contains 4 × 5 = 20 elements total.

Test

Q.6 Easy Arrays & Strings

In the declaration char *str[5], what does the array represent?

A Array of 5 character pointers

B Pointer to array of 5 characters

C Single pointer to a string of 5 characters

D 5 pointers to individual characters

Correct Answer: A. Array of 5 character pointers

EXPLANATION

The syntax char *str[5] declares an array of 5 pointers, each pointing to a character (or string). The brackets bind tighter than asterisk.

Test

Q.7 Easy Arrays & Strings

Which of the following correctly initializes a 2D array of integers?

A int arr[3][3] = {1,2,3,4,5,6,7,8,9};

B int arr[][] = {1,2,3,4,5,6};

C int arr[3][] = {{1,2},{3,4},{5,6}};

D int arr[3][3];

Correct Answer: A. int arr[3][3] = {1,2,3,4,5,6,7,8,9};

EXPLANATION

Option A is valid - 2D arrays can be initialized with all elements in a single brace. Options B and C are invalid as at least one dimension must be specified.

Test

Q.8 Easy Arrays & Strings

What is the size of the string 'Hello' when stored in a character array with null terminator?

A 5 bytes

B 6 bytes

C 7 bytes

D Depends on compiler

Correct Answer: B. 6 bytes

EXPLANATION

'Hello' has 5 characters plus 1 null terminator (\0), making total 6 bytes.

Test

Q.9 Easy Arrays & Strings

In C, when you declare an array like int arr[10], what does the array name 'arr' represent?

A A constant pointer to the first element of the array

B A variable pointer that can be reassigned

C The total size of the array in bytes

D A reference to the last element

Correct Answer: A. A constant pointer to the first element of the array

EXPLANATION

Array names decay to pointers to their first element in most contexts. 'arr' is equivalent to &arr[0] and cannot be reassigned.

Test

Q.10 Easy Arrays & Strings

How many times will the following loop execute?
int arr[5]; for(int i=0; i

A 4 times

B 5 times

C Infinite loop

D 0 times

Correct Answer: B. 5 times

EXPLANATION

Loop runs from i=0 to i=4, executing 5 times total. All array elements are initialized to 0.

Test

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Arrays & Strings