Computer Knowledge - MCQ Practice Questions

A 2D array in C is declared using the syntax: datatype arrayName[rows][columns]. So 'int arr[3][4];' creates a 2D array with 3 rows and 4 columns.

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.

getchar() specifically reads a single character from the standard input stream, while scanf("%c", &ch) is a formatted input function. getchar() is more straightforward for reading single characters.

The array has 5 rows and 3 columns, so total elements = 5 × 3 = 15 elements. Each int typically occupies 4 bytes. Total memory = 15 × 4 = 60 bytes (assuming sizeof(int) = 4 bytes on most 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 do-while loop executes the body at least once before checking the condition. The syntax is: do { statements; } while(condition);. In contrast, while and for loops check the condition first.

Variables declared inside a block (enclosed in curly braces) have local or block scope. They are accessible only within that block and cease to exist once the block execution is complete.

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.

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.