C questions in placement tests and university exams are rarely about syntax alone. Most of what you will find here is output prediction, pointer arithmetic, arrays and strings, structures and unions, storage classes, recursion, and file handling. The explanations walk through memory behaviour step by step, which is usually where the confusion sits rather than in the code itself.
What is the size of a 'float' data type in C on most 32-bit systems?
Answer: B
On most 32-bit systems, float occupies 4 bytes (32 bits) of memory according to IEEE 754 standard.
Q.142Easy
What is the range of 'signed char' in C?
Answer: B
Signed char uses 8 bits with one bit for sign, giving range -128 to 127 (2^7 to 2^7-1).
Q.143Medium
Which keyword is used to make a variable retain its value between function calls?
Answer: B
Static variables retain their values between function calls and are initialized only once, maintaining state across invocations.
Q.144Medium
What is the output of the following code? int x = 10; int *p = &x; printf("%d", *p + 5);
Answer: B
*p dereferences pointer to get value 10, then 10+5=15 is printed.
Q.145Medium
Which of the following declarations allocates memory for a variable?
Answer: D
Both 'int x;' and 'static int x;' allocate memory. Extern only declares without allocation.
Q.146Hard
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.147Medium
What will be the output of: printf("%ld", sizeof(long double));
Answer: D
Size of long double varies: typically 12 or 16 bytes on different systems and compilers.
Q.148Medium
Which storage class has global scope and external linkage by default?
Answer: C
Global variables with extern keyword have global scope and external linkage across translation units.
Q.149Hard
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.150Hard
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.151Easy
What happens if you assign a double value to an int variable without casting?
Answer: B
Implicit conversion truncates decimal part. int x = 3.7; results in x=3 with no error.
Q.152Medium
What is the purpose of the 'volatile' keyword?
Answer: B
Volatile prevents compiler optimizations by signaling the variable may change outside program control (hardware/signals).
Q.153Medium
Which variable declaration uses automatic storage duration?
Answer: C
Local variables declared inside functions have automatic storage duration and are destroyed on function exit.
Q.154Medium
What is the result of: printf("%d", (int)(3.9) + 0.5);?
Answer: A
(int)(3.9) = 3, then 3 + 0.5 = 3.5, but %d prints as int 3 (truncated).
Q.155Medium
What is the behavior of 'auto' keyword in modern C (C99 onwards)?
Answer: B
In C99+, auto is rarely used since local variables are automatic by default, but it remains valid syntax.
Q.156Hard
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.157Easy
What is the size of the 'char' data type in C on most modern systems?
Answer: A
The 'char' data type occupies 1 byte (8 bits) of memory on virtually all modern C systems, as per the C standard.
Q.158Medium
What will be the output of: int x = 10; printf("%u", -x);
Answer: B
When -10 is assigned to an unsigned int format (%u), it gets interpreted as a large positive number due to two's complement representation on a 32-bit system.
Q.159Easy
What is the difference between 'signed' and 'unsigned' char?
Answer: B
Signed char ranges from -128 to 127, while unsigned char ranges from 0 to 255. Both use 1 byte but interpret the bits differently.
Q.160Medium
Which keyword is used to declare a variable that maintains its value between function calls?
Answer: B
The 'static' keyword gives a variable static storage duration, preserving its value between function calls.
