Computer Knowledge - MCQ Practice Questions

Step 1: x = 5. Step 2: x += 3 means x = x + 3 = 5 + 3 = 8. Step 3: x *= 2 means x = x * 2 = 8 * 2 = 16. Therefore, x = 16.

In C, when an array name is used in most contexts, it decays (converts) to a pointer to its first element. For example, in int arr[5];, arr behaves like &arr[0]. However, arrays and pointers are not identical; arrays have fixed size while pointers are variables.

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.

Custom/local header files are included using double quotes: #include "filename". Standard library headers use angle brackets: #include <filename>. The compiler searches for quoted files in the current directory first.

A function declaration (or prototype) tells the compiler about the function's name, return type, and parameters. A function definition includes the declaration along with the function body containing the actual implementation. Declaration is optional if the function is defined before use.

The correct syntax for a function pointer is: int (*ptr)(int, int);. The parentheses around (*ptr) are necessary to indicate that ptr is a pointer to a function, not a function returning a pointer. Option A declares a function returning an int pointer.

Variable names in C cannot start with a digit. They must begin with a letter (a-z, A-Z) or underscore (_). '123myVar' is invalid.

Operator precedence: multiplication (*) is performed before addition (+). So: 3 * 2 = 6, then 5 + 6 = 11.

The asterisk (*) symbol is used to declare pointer variables. For example: int *ptr; declares a pointer to an integer.

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.