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 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.62Medium
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.63Hard
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.64Hard
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.65Easy
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.66Medium
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.67Medium
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.68Medium
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.69Medium
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.70Hard
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.71Easy
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.72Medium
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.73Easy
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.74Medium
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.
Q.75Medium
What is the size of 'long long' data type in C99 standard?
Answer: C
C99 standard guarantees 'long long' to be at least 64 bits (8 bytes), but some systems may allocate more.
Q.76Medium
What will be printed: float f = 25; printf("%f", f);
Answer: B
25 performs integer division resulting in 2, which is then stored in float f. printf("%f") prints 2.000000 (default 6 decimal places).
Q.77Easy
Which data type would be most appropriate to store a person's age in a program?
Answer: C
Age is an integer value. Using 'int' is appropriate and memory-efficient. Floating-point types are unnecessary for this discrete value.
Q.78Easy
What is the output of: int a = 5, b = 2; printf("%d", a / b);
Answer: B
Both a and b are integers, so integer division is performed: 25 = 2 (remainder discarded).
Q.79Medium
What happens when you declare a variable without initializing it in C?
Answer: B
Uninitialized local variables contain garbage values (whatever was in memory). Only static/global variables are zero-initialized.
Q.80Medium
Which storage class specifier limits a variable's scope to the current file?
Answer: B
The 'static' keyword, when used at file scope, restricts the variable's visibility to that file only (internal linkage).
