Computer Knowledge - MCQ Practice Questions

strlen() counts characters excluding the null terminator. "Hello" has 5 characters, so strlen(s) returns 5.

The left shift operator (<<) shifts bits to the left by 1 position, which is equivalent to multiplying by 2. So 5 << 1 = 10.

p points to arr, so p[5] is equivalent to *(p+5) which gives the value at arr[5].

The void pointer is a generic pointer that can hold addresses of any data type. void is also used for functions returning nothing and parameters.

The #define directive replaces MAX with 10 during preprocessing. So x = 10 and output is 10. (Note: semicolon after MAX is not needed but doesn't affect the output)

All three functions can read strings, though gets() is deprecated due to security issues. fgets() is safer as it limits input size.

sizeof(arr) gives total size of array. sizeof(arr[0]) gives size of one element. Dividing gives the number of elements: $\frac{20}{4}$ = 5.

Both syntaxes are correct. C allows initializing 2D arrays with or without explicit braces for each row.

Integer division truncates the decimal part. $\frac{5}{2}$ = 2 (not 2.5) because both operands are integers.

getchar() reads a single character from standard input (stdin) and returns its ASCII value.

The == operator compares values. Since a and b both have value 5, the condition is true and "Equal" is printed.

The %d format specifier prints the ASCII value of the character. 'A' has ASCII value 65.

The stdio.h header file contains declarations for standard input/output functions like printf(). Option A is C++, Option C is C++, and Option D is for memory allocation functions.

sizeof(arr) returns the total size of the array in bytes. An array of 5 integers, where each int is 4 bytes, equals 5 × 4 = 20 bytes.

malloc() is the standard C library function for dynamic memory allocation. It returns a void pointer to the allocated memory block, which can be cast to the required data type.

The break statement terminates the current loop or switch block and transfers control to the statement following the loop or switch. Without it, execution continues to the next case (fall-through).

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.

Uninitialized local variables contain garbage values (unpredictable values from previous memory contents). Global and static variables are automatically initialized to 0, but local variables are not.