Computer Knowledge - MCQ Practice Questions

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.

Only p is declared as a pointer (int *p). The variable q is declared as a regular integer (int q). The * applies only to p in this declaration.

sizeof(s) includes the null terminator '\0'. "hello" has 5 characters + 1 null terminator = 6 bytes. If s was a pointer, sizeof would give pointer size.

Modulus, multiplication, and division have equal precedence (left-to-right): (5 % 2) = 1, then (1 * 3) = 3, then ($\frac{3}{2}$) = 1 (integer division). Answer is 1, not 2. Correction: 1 is correct.

In a union, all members share the same memory location. The size of the union equals the size of the largest member. Only one member can hold a value at a time.

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

The correct syntax is 'int *p;' where int is the data type, * indicates pointer, and p is the pointer variable name.

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.

Using <> tells the compiler to search in standard system directories. Using "" tells it to search in the current directory first, then system directories. Generally, "" is used for user-defined headers and <> for standard library headers.

When p points to arr, p[2] is equivalent to *(p+2) and accesses the value at arr[2]. Pointers and array names decay to pointers, and pointer indexing retrieves the value.