Computer Knowledge - MCQ Practice Questions

Due to memory alignment/padding: int x (4 bytes), char c (1 byte) + 3 bytes padding, int y (4 bytes) = 12 bytes total. The compiler adds padding to align data members to their natural boundaries for efficient memory access.

Both {} and {0} will initialize all array elements to 0. When you provide fewer initializers than array size, remaining elements are automatically set to 0.

A pointer to a pointer is declared using two asterisks (). int ptr declares a pointer that points to another pointer that points to an integer.

By the C standard, sizeof(char) is always 1 byte. A char is the smallest addressable unit in C and is defined to be 1 byte.

Variables declared inside a function have local scope (also called function scope). They are only accessible within that function and are destroyed when the function returns.

The loop initializes i to 0 and continues while i < 5. Values of i: 0, 1, 2, 3, 4. After i becomes 5, the condition is false, so the loop executes 5 times.

calloc() allocates memory and initializes all bytes to 0, takes (number of elements, size of each element). malloc() just allocates memory without initialization and takes total size. calloc() is slightly slower due to initialization.

The += operator is a compound assignment operator. x += 3 is equivalent to x = x + 3. Therefore, 5 + 3 = 8.

The correct syntax is FILE *fp = fopen("filename", "mode");. fopen() returns a pointer to a FILE structure, and the mode string specifies how to open the file ("r" for read, "w" for write, etc.).

ptr points to arr[0]. ptr + 2 points to arr[2]. *(ptr + 2) dereferences to get the value at arr[2], which is 3. Pointer arithmetic moves by the size of the data type (integers).

When i = 1, it prints 1. When i = 2, continue skips the printf() and moves to the next iteration. When i = 3, it prints 3. Output: 1 3

C does not perform bounds checking on arrays. Accessing beyond array bounds results in undefined behavior - it may access garbage values, crash, or seem to work without error. This is a common source of bugs.

x++ is post-increment. First printf uses current value (10), then x is incremented. Second printf uses new value (11). Output: 1011

Both char s[] (array notation) and char *s (pointer notation) are valid ways to pass strings to functions in C. C does not have a built-in string type; strings are represented as character arrays or pointers to char.

In a 32-bit system, the int data type typically occupies 4 bytes (32 bits). This is the standard size for integer types on most 32-bit architectures.

The stdio.h (Standard Input Output) header file contains declarations for printf(), scanf(), and other input/output functions. It is essential for console I/O operations.

Parentheses have the highest precedence in C. Expressions within parentheses are evaluated first, followed by arithmetic operators, then logical operators, and finally assignment operators.

The break statement exits or terminates the current loop immediately. Option D describes continue (which skips to next iteration), while break actually exits the loop.

The correct syntax for declaring a pointer to an integer is 'int *ptr;' where the asterisk (*) indicates that ptr is a pointer. The placement of * before the variable name is crucial.

When %d format specifier is used with a char variable, it prints the ASCII value. The ASCII value of 'A' is 65. If it were 'a', the value would be 97.