Computer Knowledge - MCQ Practice Questions

Division and multiplication have the same precedence and are evaluated left-to-right. Step 1: $\frac{10}{3}$ = 3 (integer division). Step 2: 3 * 3 = 9. Therefore, the result is 9.

When passing a 2D array to a function, the number of columns must be specified, but the number of rows is optional. Option C is the standard correct syntax.

# Understanding Pre-increment and Post-increment Operators in C

The key to solving this problem is understanding the difference between pre-increment (++x) and post-increment (x++) operators and their evaluation order.

Step 1: Evaluate Pre-increment (++x)

The pre-increment operator increases the variable first, then uses the updated value in the expression.

When ++x is evaluated, x changes from 5 to 6, and the expression uses 6.

Step 2: Evaluate Post-increment (x++) and Addition

The post-increment operator uses the current value in the expression first, then increments the variable afterward.

After the entire expression is evaluated, x++ increments x from 6 to 7, but this happens after the addition is complete.

Step 3: Calculate Final Result

The answer is (B) 12

The ternary operator syntax is: condition ? value_if_true : value_if_false. Option B is the only correctly formatted statement.

const int *ptr makes the data constant (const int * ptr). int * const ptr makes the pointer constant. The position of const matters.

malloc() returns a void pointer (void*), which can be cast to any data type pointer as needed by the programmer.

arr[5] accesses the element at index 5, which is at memory address (arr + 5). Array name arr acts as a pointer to the first element.

*p dereferences to a (10) and *q dereferences to b (20). Adding them: 10 + 20 = 30. Pointer arithmetic is used correctly here.

The pre-increment operator ++x increments x first (from 5 to 6), then assigns the new value to y. So x = 6 and y = 6.

The free() function deallocates (releases) memory that was previously allocated using malloc(), calloc(), or realloc().

The correct syntax uses the 'struct' keyword followed by the structure name and then the member declarations enclosed in braces.

Step 1: x = 10. Step 2: x += 5 means x = x + 5 = 15. Step 3: x *= 2 means x = x * 2 = 15 * 2 = 30.

The do-while loop executes the body first and then checks the condition, ensuring at least one execution. while and for loops check the condition first.

C uses row-major order to store 2D arrays in memory. The elements are stored row by row sequentially in memory.

++x is pre-increment, which increments x before assignment. So x becomes 6, then y is assigned 6. Both x and y are 6.

ptr points to arr[0] (value 10). ptr + 1 points to arr[1] (value 20). *(ptr + 1) dereferences this pointer, giving 20.

Both malloc() and calloc() allocate dynamic memory. The key difference is that malloc() allocates uninitialized memory (contains garbage values), while calloc() allocates memory and initializes all bytes to zero. calloc() also takes two arguments (number of elements and size of each element), while malloc() takes one (total bytes needed).

In array notation, arr is a pointer to the first element. *(arr + 3) dereferences the pointer that points to the 4th element (index 3). Since array indexing is 0-based: arr[0]=1, arr[1]=2, arr[2]=3, arr[3]=4. Therefore, *(arr + 3) = 4.

When p is a pointer to a structure, we cannot use p.x (dot notation) directly. The correct ways are: p->x (arrow operator) or (*p).x (dereference then dot operator). The notation p.x would be used only if p were a structure variable, not a pointer. Therefore, p.x is incorrect when p is a pointer.

A heap (binary heap) efficiently implements priority queues with O(log n) insertion and deletion of minimum/maximum elements.