Computer Knowledge - MCQ Practice Questions

In C, void function() { } is correct. In some contexts, void function(void) { } is more explicit. Options B and C use invalid keywords for this purpose.

x=5 is greater than 3, so the condition (x > 3) evaluates to true. The if block executes, printing 'Greater'.

When an array is passed to a function in C, it decays to a pointer pointing to the first element. This is why changes made in the function affect the original array.

p is a pointer storing the address of a. *p (dereferencing) gives the value at that address, which is 5. So both a and *p print 5.

stdio.h (Standard Input/Output header) contains declarations for printf(), scanf(), and other I/O functions.

Both 'const int x = 10;' and 'int const x = 10;' are valid ways to declare constants in C. The const keyword can appear before or after the type.

The * operator is the dereference operator that accesses the value at a memory address. The & operator gets the address of a variable.

sizeof() is a unary operator that returns the number of bytes occupied by a variable or data type in memory.

All three methods are valid. Option A initializes with size 5, option B auto-determines size from initialization, and option C declares without initialization.

malloc() returns a void pointer (void*) which can be cast to any pointer type. It returns NULL if memory allocation fails.

The free() function deallocates memory that was previously allocated using malloc(), calloc(), or realloc(). delete() is used in C++.

calloc(n, size) allocates n blocks of size bytes and initializes to 0. malloc(size) allocates size bytes without initialization. calloc() is typically slower due to initialization.

/* */ is used for multi-line comments in C. // is used for single-line comments and was introduced in C99.

Since both 5 and 2 are integers, integer division occurs ($\frac{5}{2}$ = 2). The result 2 is then converted to float as 2.000000.

In structures, each member has its own memory location. In unions, all members share the same memory location, so only one can hold a value at a time.

When static is used with a global variable, it restricts its scope to the file where it is declared. Without static, global variables are accessible across files using extern.

Array name decays to pointer. p[5] is equivalent to *(p+5) which is *(arr+5) or arr[5]. This demonstrates pointer arithmetic.

Declaration tells the compiler about a variable's name and type (e.g., 'extern int x;'). Definition actually allocates memory (e.g., 'int x = 5;'). A variable can be declared multiple times but defined only once.

++a increments a to 6 and returns 6. Then a++ returns 6 and increments a to 7. So b = 6 + 6 = 12.

An empty structure in C has a size of 1 byte. This is to ensure each structure instance has a unique address in memory.