Computer Knowledge - MCQ Practice Questions

The condition x < y evaluates to true (5 < 10), so the if block executes, printing 'yes'. The else block is skipped.

C supports pass by value and pass by pointer/address. 'Pass by reference' as a concept exists in C++, not in C. In C, to achieve reference-like behavior, we use pointers.

The modulus operator % returns the remainder of division. 10 % 3 = 1 (since 10 = 3 × 3 + 1). Therefore, c = 1 and the output is 1.

When a character is printed using %d format specifier, its ASCII value is printed. The ASCII value of 'A' is 65.

Step 1: x=5. Step 2: ++x makes x=6 (pre-increment, used immediately). Step 3: y = 6 + x++ = 6 + 6 = 12. Step 4: x++ increments x to 7 after use. Final: x=7, y=12.

This is XOR swap algorithm. Step 1: a = 10^20. Step 2: b = (10^20)^20 = 10. Step 3: a = (10^20)^10 = 20. Result: a=20, b=10 (values are swapped).

fgets() is the safe way to read strings including spaces. scanf("%s") stops at whitespace, gets() is deprecated and unsafe due to buffer overflow risks.

A static variable inside a function is initialized only once and retains its value between successive function calls. It has memory allocated in the data segment, not the stack.

Both are valid syntax. Option A declares an anonymous structure with immediate variable instantiation. Option B declares a named structure type that can be used later to create variables.

The increment (++) and decrement (--) operators have the highest precedence among all operators in C, followed by unary operators, then multiplicative, additive, and so on.

The while loop starts with i=0. It prints 0, then increments i to 1, prints 1, increments to 2, prints 2, increments to 3, and the condition i<3 becomes false, so the loop terminates. Output: 0 1 2

The free() function is used to deallocate memory that was previously allocated using malloc(), calloc(), or realloc(). This prevents memory leaks.

This declaration creates a pointer to an integer and initializes it to NULL, which means it doesn't point to any valid memory address. This is a safe initialization practice.

Since both 5 and 2 are integers, integer division is performed: $\frac{5}{2}$ = 2. The %f format specifier then prints this integer value (2) as a floating-point number: 2.000000

The sizeof() operator returns the size in bytes of a data type or variable. For example, sizeof(int) typically returns 4 on most 32-bit systems.

In C, the modulus operator (%) returns a remainder that has the same sign as the dividend. For example, -7 % 3 = -1 (not 2), because -7 is the dividend and it's negative.

A pointer is a variable that stores the memory address of another variable. You can access the value at that address using the dereference operator (*), and pointers can point to any data type.

Both 'const int x = 10;' and 'int const x = 10;' are valid ways to declare a constant in C. The const keyword can be placed before or after the type specifier, and both have the same meaning.

The loop executes for i=0, i=1, and i=2. When i=3, the break statement is encountered, which immediately terminates the loop. Therefore, the loop executes exactly 3 times.

All three methods are correct ways to initialize a pointer to NULL. 0, NULL, and (void*)0 all represent a null pointer. NULL is typically a macro defined as 0 or ((void*)0) in the standard library.