C Basics - Practice MCQs for CCAT

Correct Answer: C - Dennis Ritchie

C was developed by Dennis Ritchie at Bell Labs in the early 1970s.

Correct Answer: D - UNIX

C was developed to write the UNIX operating system.

Correct Answer: D - C89

C89 (ANSI C) is one of the official C language standards.

Correct Answer: D - boolean

C does not have a built-in boolean keyword.

Correct Answer: B - char

char data type is used to store a single character.

Correct Answer: B - 4 bytes

On most modern systems, int occupies 4 bytes.

Correct Answer: C - long

The long modifier increases the size/range of integer.

Correct Answer: B - const

const prevents modification of a variable.

Correct Answer: D - int

By default, main() returns an integer value.

Correct Answer: D - stdio.h

printf() is declared in stdio.h.

Correct Answer: A - ;

Every C statement ends with a semicolon.

Correct Answer: B - _num

Variable names can start with underscore.

Correct Answer: B - const

const keyword declares read-only variables.

Correct Answer: A - scanf()

scanf() is used for formatted input.

Correct Answer: C - long double

long double provides highest floating-point precision.

Correct Answer: B - 5

x is initialized to 5 and printed.

Correct Answer: C - array

Array is a derived data type.

Correct Answer: C - volatile

volatile prevents compiler optimizations.

Correct Answer: A - &

& operator returns the address of a variable.

Correct Answer: C - Platform dependent

C programs depend on underlying hardware and OS.

Correct Answer: C - printf("%d", x);

printf with %d format specifier is used to print integers.

Correct Answer: D - 1 byte

char always occupies 1 byte in C.

Correct Answer: A - unsigned int x;

Correct syntax is modifier followed by data type.

Correct Answer: B - register

register suggests the compiler to store variable in CPU register.

Correct Answer: D - 4

sizeof(int) is typically 4 bytes on modern systems.

Correct Answer: D - All of the above

Integer, floating, and character constants are valid.

Correct Answer: B - \n

\n moves the cursor to next line.

Correct Answer: A - Hello then World in next line

\n causes a line break.

Correct Answer: B - No header required

sizeof is a compile-time operator.

Correct Answer: C - Special symbols

Special symbols like @, # are not allowed.

Correct Answer: A - extern

extern is used to declare global variables across files.

Correct Answer: D - Garbage value

Uninitialized local variables contain garbage values.

Correct Answer: B - float

float stores decimal (fractional) values.

Correct Answer: A - Prevents optimization

volatile tells compiler value may change unexpectedly.

Correct Answer: C - sizeof

sizeof operator returns memory size in bytes.

Correct Answer: A - %lf

double uses %lf in scanf and printf.

Correct Answer: B - Both A and B

C supports both single-line and multi-line comments.

Correct Answer: D - A

ASCII value 65 represents character 'A'.

Correct Answer: A - void

void indicates no return value.

Correct Answer: B - return 0;

return 0 indicates successful execution.

Correct Answer: C - string

'string' is not a built-in data type in C. Strings are represented as arrays of characters (char[]). The valid primitive data types include int, float, double, char, and void.

Correct Answer: A - 45

The sizeof operator is evaluated at compile time, so the expression x++ inside sizeof is never executed at runtime. Therefore x remains 5. sizeof(int) is typically 4 bytes on most systems. The first printf prints 4, the second prints 5 (since x was never incremented). Output: 45.

Correct Answer: D - const

The 'const' keyword makes a variable read-only after initialization, preventing any modification to its value. 'static' controls storage duration, 'volatile' prevents compiler optimization, and 'register' suggests storing in a CPU register.

Correct Answer: A - 0 to 255

An unsigned char uses all 8 bits for magnitude (no sign bit), giving a range of 0 to 2⁸ - 1 = 255. A signed char uses one bit for sign, giving -128 to 127.

Correct Answer: B - 10

There is only one %d format specifier but two arguments are passed. The printf function will print the first matching argument (10) and ignore the extra argument b. This is valid C and does not cause a compilation error, though it may generate a warning.

Correct Answer: C - float 2ndValue = 3.14;

Variable names in C cannot begin with a digit. '2ndValue' starts with the digit 2, making it an invalid identifier. Valid identifiers must start with a letter (a-z, A-Z) or underscore (_), followed by letters, digits, or underscores.

Correct Answer: C - The variable's value may change unexpectedly outside the program's control

'volatile' tells the compiler that a variable's value can be changed by external factors (hardware registers, interrupt service routines, other threads), so the compiler should not optimize reads/writes to that variable and must always fetch it from memory.

Correct Answer: A - 6

When a float/double is cast to int in C, the fractional part is truncated (not rounded). So (int)3.9 = 3 and (int)3.1 = 3. Therefore 3 + 3 = 6. The %d format prints it as integer 6.

Correct Answer: D - static

A 'static' local variable is initialized only once and retains its value between function calls throughout the program's lifetime. 'auto' and 'register' variables are destroyed when the function returns. 'extern' is used to declare variables defined in other files.

Correct Answer: A - 5

The string "CDAC" has 4 visible characters, but C automatically appends a null terminator '\0' at the end. So the character array str contains {'C','D','A','C','\0'}, which is 5 bytes. sizeof(str) returns 5.