Computer Knowledge - MCQ Practice Questions

The pre-increment operator (++x) increments x from 5 to 6 before using its value in printf(). So the output is 6.

ptr[2] is equivalent to *(ptr+2), which dereferences the pointer and returns the value at the third element (index 2).

Linear search checks each element sequentially. In the worst case, it needs to check all n elements, resulting in O(n) time complexity.

ptr is reassigned to point to b. When we dereference ptr using *ptr, we get the value stored at b, which is 10.

Static variables are initialized only once and retain their value throughout the program execution. Their value persists between function calls.

On most modern 32-bit and 64-bit systems, an int is typically 4 bytes (32 bits). However, the exact size can vary depending on the compiler and system architecture.

C does not have a built-in boolean data type. The other options (float, double, char) are all valid primitive data types in C. Boolean functionality is typically implemented using int (0 for false, non-zero for true).

The & operator has two uses in C: (1) When used before a variable, it returns the memory address of that variable (address-of operator), and (2) When used between two integers, it performs a bitwise AND operation.

The const keyword is used in C to declare a constant variable whose value cannot be modified after initialization. Variables declared as const are read-only.

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