What will be the output of this code? int counter = 0; void increment() { static int count = 0; count++; counter++; } main() { increment(); increment(); printf("%d %d", count, counter); }

The correct answer is C: Compilation error - 'count' undeclared. The static variable 'count' is local to increment() and inaccessible from main(). Trying to print 'count' causes compilation error: undefined identifier.

Which of the following correctly declares a pointer to a function that takes two integers and returns an integer?

The correct answer is A: int (*ptr)(int, int);. int (*ptr)(int, int) declares a pointer to a function. int *ptr(int, int) declares a function returning pointer to int.

Which preprocessor directive is used to include standard library files?

The correct answer is C: Both A and B. #include is used for standard library files (searched in standard paths). #include "filename" is used for user-defined header files (searched in current directory first).

Which function returns the current position of file pointer?

The correct answer is B: ftell(). ftell() returns the current file position as a long integer. fgetpos() stores position in a fpos_t structure. rewind() resets to beginning.

Which of the following is a valid way to return multiple values from a function in C?

The correct answer is D: All of the above. C provides multiple methods to return values: structs for encapsulation, pointers for indirect modification, and global variables (though not recommended). All three are technically valid approaches.

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C Programming
Basics & Syntax

C language from basics to advanced placement prep

40 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 21–30 of 40

Topics in C Programming

All Basics & Syntax 86 Data Types & Variables 97 Control Flow 100 Functions 99 Arrays & Strings 100 Pointers 99 Structures & Unions 100 File Handling 100 Dynamic Memory 98 Preprocessor 99

Q.21 Medium Basics & Syntax

Which of the following is a correct way to read a string from user input avoiding buffer overflow?

A scanf("%s", str);

B scanf("%10s", str);

C gets(str);

D scanf("%[^ ]s", str);

Correct Answer: B. scanf("%10s", str);

EXPLANATION

Using scanf("%10s", str) limits input to 10 characters, preventing buffer overflow. The gets() function is deprecated and unsafe.

Test

Q.22 Medium Basics & Syntax

What does the 'const' keyword do when applied to a pointer?

A Makes the pointer value constant only

B Makes the pointed data constant only

C Can make either or both constant depending on placement

D Has no effect in C

Correct Answer: C. Can make either or both constant depending on placement

EXPLANATION

'const int *ptr' makes the data constant, 'int * const ptr' makes the pointer constant, and 'const int * const ptr' makes both constant.

Test

Q.23 Medium Basics & Syntax

What is the primary purpose of the 'volatile' keyword in C?

A To prevent variable modification

B To inform the compiler that a variable's value can change unexpectedly

C To allocate memory dynamically

D To declare function pointers

Correct Answer: B. To inform the compiler that a variable's value can change unexpectedly

EXPLANATION

The 'volatile' keyword tells the compiler not to optimize accesses to a variable, as its value can change from external sources (hardware, signals, etc.).

Test

Q.24 Medium Basics & Syntax

Which of the following correctly represents a string literal in C?

A char str = 'Hello';

B char str[] = "Hello";

C string str = "Hello";

D char *str = 'Hello';

Correct Answer: B. char str[] = "Hello";

EXPLANATION

Strings in C are represented using double quotes and stored in character arrays. Single quotes are for single characters.

Test

Q.25 Medium Basics & Syntax

What will be the output of the expression: 5/2 in C (considering integer division)?

A 2.5

B 3

C 2

D Error

Correct Answer: C. 2

EXPLANATION

In C, when both operands are integers, division performs integer division, discarding the fractional part. 5/2 = 2.

Test

Q.26 Medium Basics & Syntax

What is the range of values for 'signed char' in C (assuming 8-bit char)?

A 0 to 255

B -128 to 127

C -256 to 255

D 0 to 127

Correct Answer: B. -128 to 127

EXPLANATION

A signed char is 1 byte (8 bits) and can represent values from -128 to 127 using two's complement representation.

Test

Q.27 Medium Basics & Syntax

In C, what is the purpose of the 'static' keyword when used with a global variable?

A To make it accessible only within the current file

B To allocate it on the stack

C To make it a constant

D To prevent memory deallocation

Correct Answer: A. To make it accessible only within the current file

EXPLANATION

When 'static' is used with a global variable, it restricts its scope to the current file (internal linkage), making it not accessible from other files.

Test

Q.28 Medium Basics & Syntax

Which memory segment stores global variables in C?

A Stack

B Heap

C Data segment

D Code segment

Correct Answer: C. Data segment

EXPLANATION

Global variables are stored in the data segment (also called BSS segment for uninitialized globals). Local variables use the stack.

Test

Q.29 Medium Basics & Syntax

Which of the following is NOT a valid data type modifier in C?

A unsigned long

B signed double

C long float

D unsigned char

Correct Answer: C. long float

EXPLANATION

The 'long' modifier cannot be used with 'float'. You can only use 'double' or 'long double' for longer floating-point types.

Test

Q.30 Medium Basics & Syntax

What is the output of the following code?
#include
int main() {
int a = 5, b = 10;
a = b++;
printf("%d %d", a, b);
return 0;
}

A 5 10

B 10 11

C 11 11

D 10 10

Correct Answer: B. 10 11

EXPLANATION

b++ returns the current value of b (10) before incrementing, so a = 10. Then b increments to 11.

Test

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Basics & Syntax