C Programming - MCQ Practice Questions

Both 'const int' and 'int const' are valid and equivalent ways to declare a constant integer in C.

unsigned char is 1 byte (8 bits) without sign bit, giving range 0 to 2^8-1 = 0 to 255.

C allows implicit type conversion. When assigning larger to smaller type, truncation or data loss may occur without any compiler error.

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.

Variables declared inside a block (including function blocks) have block scope and are accessible only within that block.

The storage classes in C are: auto, register, static, and extern. 'static' is one of them.

# Understanding `sizeof()` Operator in C

The `sizeof()` operator returns the size of data types in bytes, which varies depending on the compiler and system architecture.

Step 1: Analyze sizeof(int)

In C, the size of `int` is implementation-defined and depends on the system architecture and compiler.

Step 2: Analyze sizeof(char) and Calculate Total

The `char` data type always occupies exactly 1 byte across all standard C implementations, but `int` varies by platform.

For a 16-bit system: $2+1=3$ bytes

For a 32-bit system: $4+1=5$ bytes

For a 64-bit system: $4+1=5$ bytes (typically)

The output depends on the system's architecture. The minimum guaranteed value is 3 bytes (on 16-bit systems), but it can be higher on modern systems.

Correct Answer: (C) Depends on system (at least 3)

char (signed) has range -128 to 127, while unsigned char has 0 to 255. The latter can represent extended ASCII characters (128-255).

When assigning a double to int, C performs implicit type conversion with truncation (not rounding). The decimal part is discarded.

Initialization assigns a value when the variable is declared (int x = 5;). Assignment changes the value later (x = 10;).

Uninitialized local variables contain garbage values (random data from memory). Static/global variables are initialized to 0 by default.

%ld is for long int, %lld is for long long int, and %d is for regular int. Using wrong specifier can cause undefined behavior.

The '*' applies only to the immediately following variable. So 'int *p' declares p as pointer to int, and 'q' is just an int.

restrict (C99) informs the compiler that a pointer is the sole accessor to the object, enabling optimization. It doesn't prevent modification.

On most 32-bit systems, float occupies 4 bytes (32 bits) of memory according to IEEE 754 standard.

Signed char uses 8 bits with one bit for sign, giving range -128 to 127 (2^7 to 2^7-1).

Static variables retain their values between function calls and are initialized only once, maintaining state across invocations.

*p dereferences pointer to get value 10, then 10+5=15 is printed.

Both 'int x;' and 'static int x;' allocate memory. Extern only declares without allocation.

'const int *p' - pointer can change but value cannot. 'int * const p' - value can change but pointer cannot.