Q.41
Medium
In C, what does the scanf() function do?
A
Displays output to the screen
B
Reads input from standard input (keyboard)
C
Creates a new variable
D
Allocates memory
Correct Answer:
B. Reads input from standard input (keyboard)
Explanation:
scanf() reads formatted input from the standard input device (usually keyboard). printf() displays output. Both require #include <stdio.h>.
Q.42
Medium
What will be the output of: for(int i = 0; i < 3; i++) { printf("%d ", i); }?
A
0 1 2
B
1 2 3
C
0 1 2 3
D
3 2 1
Explanation:
Loop runs with i=0,1,2. When i=3, condition i<3 becomes false and loop terminates. Output: 0 1 2 (with spaces).
Q.43
Medium
Which of the following is the correct way to define a function that takes no parameters and returns no value?
A
void function() { }
B
null function() { }
C
empty function() { }
D
void function(void) { }
Correct Answer:
A. void function() { }
Explanation:
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.
Q.44
Medium
What is the output of the following program: int x = 5; if(x > 3) printf("Greater"); else printf("Smaller");?
A
Smaller
B
Greater
C
5
D
Error
Correct Answer:
B. Greater
Explanation:
x=5 is greater than 3, so the condition (x > 3) evaluates to true. The if block executes, printing 'Greater'.
Q.45
Medium
What is the return type of the malloc() function?
A
int
B
void*
C
char*
D
null
Explanation:
malloc() returns a void pointer (void*) which can be cast to any pointer type. It returns NULL if memory allocation fails.
Q.46
Medium
Which function is used to release dynamically allocated memory in C?
A
delete()
B
free()
C
release()
D
dealloc()
Correct Answer:
B. free()
Explanation:
The free() function deallocates memory that was previously allocated using malloc(), calloc(), or realloc(). delete() is used in C++.
Q.47
Medium
What is the difference between calloc() and malloc()?
A
calloc() initializes memory to zero, malloc() does not
B
malloc() is faster than calloc()
C
calloc() takes two arguments, malloc() takes one
D
All of the above
Correct Answer:
D. All of the above
Explanation:
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.
Q.48
Medium
Which of the following is used to comment multiple lines in C?
A
// comment
B
/* comment */
C
# comment
D
-- comment
Correct Answer:
B. /* comment */
Explanation:
/* */ is used for multi-line comments in C. // is used for single-line comments and was introduced in C99.
Q.49
Medium
What will be the output of: float x = 5/2; printf("%f", x);
A
2.500000
B
2.000000
C
2.5
D
Compilation Error
Correct Answer:
B. 2.000000
Explanation:
Since both 5 and 2 are integers, integer division occurs (5/2 = 2). The result 2 is then converted to float as 2.000000.
Q.50
Medium
How are structures different from unions in C?
A
Structures allocate separate memory for each member, unions share memory
B
Unions allocate separate memory for each member, structures share memory
C
There is no difference
D
Structures are faster than unions
Correct Answer:
A. Structures allocate separate memory for each member, unions share memory
Explanation:
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.
