Which of the following correctly demonstrates pointer arithmetic?
Answer: A
Option A shows pointer arithmetic where p++ increments the pointer by the size of int (4 bytes). Other options are regular arithmetic operations.
Q.22Hard
What is the output of the following code?
int a = 5;
int *p = &a;
int q = &p;
printf("%d", q);
Answer: A
q is a pointer to pointer p. **q dereferences both pointers, giving the value of a, which is 5.
Q.23Hard
What is true about the variable declared as 'extern int count;' inside a function?
Answer: B
extern is a declaration (not definition) that tells compiler the variable exists elsewhere in program. It provides global scope.
Q.24Hard
Consider a structure with int (4 bytes), char (1 byte), and double (8 bytes). What is the minimum size due to alignment requirements?
Answer: C
Due to structure padding/alignment, the size becomes 24 bytes (8-byte alignment for double). Members are padded to maintain alignment.
Q.25Hard
Which of the following statements about type qualifiers is INCORRECT?
Answer: C
restrict prevents pointer aliasing (not allows). It tells compiler that pointer is the only way to access that object.
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Q.26Hard
In the declaration 'volatile int x;', what does volatile signify?
Answer: A
volatile tells the compiler that the variable's value may change unexpectedly (e.g., by hardware, signals, or another thread), so the compiler should not optimize it.
Q.27Hard
In the declaration 'int *p, q;', what are the data types?
Answer: B
The '*' applies only to the immediately following variable. So 'int *p' declares p as pointer to int, and 'q' is just an int.
Q.28Hard
What is the purpose of the 'restrict' keyword in modern C?
Answer: B
restrict (C99) informs the compiler that a pointer is the sole accessor to the object, enabling optimization. It doesn't prevent modification.
Q.29Hard
What is the difference between 'const int *p' and 'int * const p'?
Answer: C
'const int *p' - pointer can change but value cannot. 'int * const p' - value can change but pointer cannot.
Q.30Hard
What is printed by: int x = 5; printf("%d %d", x++, ++x);?
Answer: C
Modifying variable x twice without intervening sequence point causes undefined behavior.
Q.31Hard
Which of the following correctly declares a constant pointer to a constant integer?
Answer: D
Both 'const int * const p' and 'int const * const p' are equivalent and declare constant pointer to constant integer.
Q.32Hard
Which of the following statements about 'register' keyword is TRUE?
Answer: D
Register is a hint only; compiler may ignore it. You cannot use & operator on register variables.
Q.33Hard
What is the primary purpose of the 'restrict' keyword introduced in C99?
Answer: B
The 'restrict' qualifier tells the compiler that a pointer is the only way to access that object, enabling optimizations.
Q.34Hard
What happens in this code: int arr[5]; int *p = &arr[0]; printf("%d", sizeof(p));
Answer: B
p is a pointer variable, so sizeof(p) returns the size of the pointer itself (4 bytes on 32-bit, 8 bytes on 64-bit systems), not the array.
Q.35Hard
What will be the result of the following expression:
float x = 0.1 + 0.2;
if(x == 0.3) printf("Equal"); else printf("Not Equal");
Answer: B
Due to floating-point precision limitations, 0.1 + 0.2 does not exactly equal 0.3 in binary representation. Direct comparison with == fails.
Q.36Hard
What happens when a volatile variable is declared in a multi-threaded C program?
Answer: B
volatile tells compiler not to optimize variable accesses and to fetch fresh value from memory, useful for hardware registers and shared memory, but doesn't guarantee thread-safety without synchronization.
Q.37Hard
What is the output of this program?
for (int i = 1; i <= 3; i++)
for (int j = 1; j <= 2; j++)
printf("%d", i*j);
printf("\n");
Answer: A
Nested loops: outer i=1,2,3; inner j=1,2. Prints products: 1*1=1, 1*2=2 (newline), 2*1=2, 2*2=4 (newline), etc.
Q.38Hard
What is the output of this complex nested control flow?
int x = 1, y = 2;
if (x < y) {
x++; y--;
if (x == y)
printf("Equal");
else
printf("NotEqual");
}
Answer: A
x=1, y=2. Since 1 < 2, x becomes 2 and y becomes 1. Now x != y, but after operations x=2, y=1. Wait: x++ makes x=2, y-- makes y=1. So x==y is false, printing 'NotEqual'. Rechecking: 1 < 2 is true, so enter if. x becomes 2, y becomes 1. 2 == 1 is false, so else executes, printing 'NotEqual'.
Q.39Hard
What happens when continue is used in a for loop with a post-increment expression?
Answer: B
When continue is executed in a for loop, the post-increment (i++) still executes before the condition is checked again. Only the body statements after continue are skipped.
Q.40Hard
What is the effect of using multiple break statements in nested loops?
Answer: C
Each break statement exits only its immediately enclosing loop. To exit multiple nested loops, you need one break for each level you want to exit.
