C MCQ: C Multiple Choice Questions And Answers

C MCQ with answers and explanations for placement tests and job interviews. These solved C programming MCQ questions are useful for the campus placement of all freshers including Engineering Students, MCA students, Computer and IT Engineers, etc.

Our C MCQ ( C multiple Choice Questions ) focuses on all areas of the C programming language. We will regularly update the quiz and most interesting thing is that questions come in a random sequence. So every time you will feel new questions.

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C MCQ: C Programming Multiple Choice Questions And Answers

1 / 71

Which statement is not true in C programming?

char *ptr;

string p;

char str[];

char ch;

2 / 71

How will you free the allocated memory in C?

remove(pointer-name);

delete(pointer-name);

free(pointer-name);

dalloc(pointer-name);

3 / 71

Which is the correct option

A pointer type shall not be converted to any floating type.

A floating type shall not be converted to any pointer type.

Both are true

Both are false

4 / 71

Which of the following is correct for a function definition along with storage-class specifier in C language?

int fun(auto int arg)

int fun(static int arg)

int fun(register int arg)

int fun(extern int arg)

All of the above are correct.

As per C standard, “The only storage-class specifier that shall occur in a parameter declaration is register.” That’s why correct answer is C.

5 / 71

For a given integer, which of the following operators can be used to “set” and “reset” a particular bit respectively?

&& and ||

| and &

|| and &&

&& and ||

6 / 71

Pick the best statement for the below program snippet:

struct {int a[2];} arr[] = {1,2};

No compile error and it’ll create array arr of 2 elements. Each of the element of arr contain a struct field of int array of 2 elements. arr[0]. a[0] would be 1 and arr[0].a[1] would be 2. The second element arr[1] would be ZERO i.e. arr[1].a[0] and arr[1].a[1] would be 0.

No compile error and it’ll create array arr of 2 elements. Each of the element of arr contain a struct field of int array of 2 elements. arr[0]. a[0] would be 1 and arr[1].a[0] would be 2.

No compile error and it’ll create array arr of 1 element. Each of the element of arr contain a struct field of int array of 2 elements. arr[0]. a[0] would be 1 and arr[0].a[1] would be 2.

Since size of array arr isn’t given explicitly, it would be decided based on the initialization here. Without any curly braces, arr is initialized sequentially i.e. arr[0].a[0] would be 1 and arr[0].a[1] would be 2. There’s no further initialization so size of arr would be 1. Correct answer is C.

7 / 71

Consider the following variable declarations and definitions in C

i) int var_9 = 1;
ii) int 9_var = 2;
iii) int _ = 3;

Choose the correct statement w.r.t. above variables.

Both i) and iii) are valid.

Both i) and ii) are valid.

ii) are valid.

None of the above

In C language, a variable name can consists of letters, digits and underscore i.e. _ . But a variable name has to start with either letter or underscore. It can't start with a digit. So valid variables are var_9 and _ from the above question. Even two back to back underscore i.e. __ is also a valid variable name. Even _9 is a valid variable. But 9var and 9_ are invalid variables in C. This will be caught at the time of compilation itself. That's why the correct answer is A).

8 / 71

“typedef” in C basically works as an alias. Which of the following is correct for “typedef”?

typedef can be used to alias compound data types such as struct and union.

typedef can be used to alias both compound data types and pointer to these compound types.

typedef can be used to alias a function pointer.

typedef can be used to alias an array.

All of the above.

In C, typedef can be used to alias or make synonyms of other types. Since function pointer is also a type, typedef can be used here. Since, array is also a type of symmetric data types, typedef can be used to alias array as well.

9 / 71

Point out the correct statement about call by value

Pass By Value copies the variable value in one more memory location.

Pass By Value does not use Pointers.

Pass By Value protects your source or original variables from changes in outside functions or called functions.

All of the above.

10 / 71

What’s the meaning of following declaration in C language?

int (*p)[5];

It will result in compile error because there shouldn't be any parenthesis i.e. “int *p[5]” is valid.

p is a pointer to 5 integers.

p is a pointer to integer array.

p is an array of 5 pointers to integers.

p is a pointer to an array of 5 integers

11 / 71

Can we combine the two statements?

char *p;

p = (char*) malloc(100);

char *p = (char *)(malloc*)(100);

char *p = (char*)malloc(100);

char p = *malloc(100);

char *p = (char) malloc(100);

12 / 71

Which of the following statement is correct for switch controlling expression?

Only int can be used in “switch” control expression.

Both int and char can be used in “switch” control expression.

All types i.e. int, char and float can be used in “switch” control expression.

“switch” control expression can be empty as well.

13 / 71

In the following code, the P2 is Integer Pointer or Integer?

typedef int *ptr;
ptr p1, p2;

Error in declaration

Integer

Integer pointer

None of the above

14 / 71

Which of the following functions from “stdio.h” can be used in place of printf()?

fputs() with FILE stream as stdout.

fprintf() with FILE stream as stdout.

fwrite() with FILE stream as stdout.

All of the above three - a, b and c.

In “stdio.h”, there’s no other equivalent function of printf().

Though fputs() and fwrite() can accept FILE stream stdout and can output the given string but the input string wouldn’t result in formatted (i.e. containing format specifiers) output. But fprintf() can be used for formatted output. That’s why fprintf(stdout,"=%d=",a); and printf("=%d=",a); both are equivalent. The correct answer is B.

15 / 71

In a C file (say sourcefile1.c), an array is defined as follows. Here, we don’t need to mention arrary arr size explicitly in [] because the size would be determined by the number of elements used in the initialization.

int arr[] = {1,2,3,4,5};

In another C file (say sourcefile2.c), the same array is declared for usage as follows:

extern int arr[];

In sourcefile2.c, we can use sizeof() on arr to find out the actual size of arr.

True

False

First thing first, sizeof() operator works at compile time. So usage of sizeof on arr in sourcefile2.c won’t work because arr in sourcefile2.c is an incomplete type. Please note that arr in sourcefile1.c is a complete type because size of array got determined at compile time due to initialization.

16 / 71

C variable cannot start with a

number

Any special symbol except underscore

both a and b

None of the above

17 / 71

Which of the following is not a logical operator

||

&&

!=

&=

18 / 71

Are the expressions arr and &arr same for an array of 5 integers?

Yes

No

19 / 71

What is the value of a[4]?

int a[5]={1,2,4,1,0}

0

1

4

None of the above

20 / 71

calloc(m, n); is equivalent to

memset(0, m*n);

ptr = malloc(m*n); strcpy(p, u);

ptr = malloc (m*n); memset (p, 0, m*n);

All of the above

21 / 71

Suppose a, b, c and d are int variables. For ternary operator in C ( ? : ), pick the best statement.

a>b ? c=10 : d=10; is valid statement. Based on the value of a and b, either c or d gets assigned the value of 10.

a>b ? : ; is valid statement i.e. 2nd and 3rd operands can be empty and they are implicitly replaced with non-zero value at run-time.

a>b ? (c=10,d=20) : (c=20,d=10); is valid statement. Based on the value of a and b, either c=10,d=20 gets executed or c=20,d=10 gets executed.

All of the above are valid statements for ternary operator.

For ternary operator, both 2nd and 3rd operands are necessary. So A) isn’t correct. As per operator precedence, ternary operator has higher precedence over assignment operator. So B) isn’t correct.

22 / 71

For the following declaration of a function in C, pick the best statement

int [] fun(void (*fptr)(int *));

It will result in compile error.

No compile error. fun is a function which takes a function pointer fptr as argument and return an array of int.

No compile error. fun is a function which takes a function pointer fptr as argument and returns an array of int. Also, fptr is a function pointer which takes int pointer as argument and returns void.

No compile error. fun is a function which takes a function pointer fptr as argument and returns an array of int. The array of int depends on the body of fun i.e. what size array is returned. Also, fptr is a function pointer which takes int pointer as argument and returns void.

As per C standard, a function can’t have an explicit array as return type. That’s why the above would result in compile error. There’re indirect ways if we need an array as an output of a function call. For example, a pointer can be returned by function by return statement while providing the size of array via other means. Alternatively, function argument can be used for this.

23 / 71

What is (void*)0?

Representation of void pointer

Representation of NULL pointer

Compiler error

None of the above

24 / 71

In C, if you pass an array as an argument to a function, what actually gets passed?

Value of elements in array

First element of the array

Address of the last element of array

Base address of the array

25 / 71

In a C program, the following variables are defined:

float x = 2.17;

double y = 2.17;

long double z = 2.17;

Which of the following is the correct way for printing these variables via printf?

printf("%f %lf %Lf",x,y,z);

printf(“%f %f %f”,x,y,z);

printf("%f %ff %fff",x,y,z);

printf("%f %lf %llf",x,y,z);

In C language, float, double and long double are called real data types. For “float”, “double” and “long double”, the right format specifiers are %f, %lf and %Lf from the above options. It should be noted that C standard has specified other format specifiers as well for real types which are %g, %e etc.

26 / 71

enum types are processed by

Assembler

Pre-processor

Compiler

Linker

27 / 71

Suppose a C program has floating constant 1.414, what's the best way to convert this as a "float" data type?

(float)1.414

float(1.414)

1.414f or 1.414F

1.414 itself of "float" data type i.e. nothing else required.

By default floating constant is of the double data type. By suffixing it with f or F, it can be converted to float data type

28 / 71

Which bitwise operator is suitable for checking whether a particular bit is on or off?

&&

&

||

|

29 / 71

What will happen if in a C program you assign a value to an array element whose subscript exceeds the size of array?

The element will be set to 0.

The program may crash if some important data gets overwritten.

The compiler would report an error.

The array size would appropriately grow.

30 / 71

For the following “typedef” in C, pick the best statement

typedef int INT, *INTPTR, ONEDARR[10], TWODARR[10][10];

It will cause compile error because typedef is being used to define multiple aliases of incompatible types in the same statement.

“INT x” would define x of type int. Remaining part of the statement would be ignored.

“INT x” would define x of type int and “INTPTR y” would define pointer y of type int *. Remaining part of the statement would be ignored.

“INT x” would define x of type int. “INTPTR y” would define pointer y of type int *. ONEDARR is an array of 10 int. TWODARR is a 2D array of 10 by 10 int.

“INT x” would define x of type int. “INTPTR *y” would define pointer y of type int **. “ONEDARR z” would define z as array of 10 int. “TWODARR t” would define t as array of 10 by 10 int.

Here, INT is alias of int. INTPTR is alias of int *. That’s why INTPTR * would be alias of int **. Similarly, ONEDARR is defining the alias not array itself. ONEDARR would be alias to int [10]. That’s why “ONEDARR z” would define array z of int [10]. Similarly, TWODARR would be alias to int [10][10]. Hence “TWODARR t” would define array t of int [10][10]. We can see that typedef can be used to create alias or synonym of other types.

31 / 71

Is there any difference between the following two statements?

char *p=0;

char *t=NULL;

No

Yes

32 / 71

If a two-dimensional array is used as a formal parameter, then

the first subscript must be left empty

the first (row) subscript may be left empty

both the subscripts must be left empty

both the subscripts may be left empty

33 / 71

Are the expression *ptr++ and ++*ptr are same?

True

False

34 / 71

In the context of C data types, which of the following is correct?

“unsigned long long int” is a valid data type

“long long double” is a valid data type

“unsigned long double” is a valid data type.

a), b) and c) all are valid data types.

a) and c) all are valid data types.

35 / 71

Bit fields CANNOT be used in the union.

Yes

No

36 / 71

The default return type of function definition

int

float

void

double

37 / 71

Are the three declarations char **apple, char *apple[], and char apple[][] same?

True

False

38 / 71

In the below statement, ptr1 and ptr2 are uninitialized pointers to int i.e. they are pointing to some random address that may or may not be valid address.

int* ptr1, ptr2;

True

False

Even though * is placed closer to int, * would be associated to ptr1 only but not to ptr2. It means that “int* ptr1” is equal to “int *ptr1”. That’s why only ptr1 is uninitialized pointer to int. Basically, though both ptr1 and ptr2 are uninitialized variables yet ptr1 is pointer to int while ptr2 is variable of type int. If we really want to make both variables as pointers, we need to mention them as “int *ptr1, *ptr2;”

39 / 71

If storage class is missing in the array definition, by default it will be taken to be

either automatic or external depending on the place of occurrence

static

external

automatic

40 / 71

Which of the following declaration is illegal?

int *a[] = {{1, 2, 3}, {2, 3, 4, 5}};

int a[][] = {{1, 2, 3}, {2, 3, 4, 5}};

Both a and b

None of the above

41 / 71

Which header file is the NULL macro defined?

stdio.h

math.h

stddef.h

stdio.h and stddef.h

42 / 71

In the context of "break" and "continue" statements in C, pick the best statement.

“break” can be used in “for”, “while” and “do-while” loop body.

“continue” can be used in “for”, “while” and “do-while” loop body.

“break” and “continue” can be used in “for”, “while”, “do-while” loop body and “switch” body.

“break” and “continue” can be used in “for”, “while” and “do-while” loop body. But only “break” can be used in “switch” body.

“break” and “continue” can be used in “for”, “while” and “do-while” loop body. Besides, “continue” and “break” can be used in “switch” and “if-else” body.

As per C standard, “continue” can be used in the loop body only. “break” can be used in the loop body and switch body only. That’s why the correct answer is d.

43 / 71

Which keyword is used to give back the value?

static

void

return

const

44 / 71

Select the type of linkage in C

None

External

External and Internal

External, Internal and None

45 / 71

If a variable is a pointer to a structure, then which of the following operator is used to access data members of the structure through the pointer variable?

*

>-

->

.

46 / 71

Select false statement

A variable must be declared and defined at the same time

A single variable cannot be defined with two different types in the same scope

A variable defined once can be defined again with different scope

All of the above

47 / 71

The operator used to get value at address stored in a pointer variable is

&

*

&&

.

48 / 71

No of values function can return

0

1

5

2

49 / 71

Which of the following statements correct about k used in the below statement?

char ****k;

k is a pointer to a pointer to a pointer to a char

k is a pointer to a char pointer

k is a pointer to a pointer to a pointer to a pointer to a char @

k is a pointer to a pointer to a char

50 / 71

A function used in the round off the value

roundoff()

roundto()

ceil()

None of the above

51 / 71

It is not advisable to use macros instead of functions because

it increases the code size

no type checking will be done

recursion is not possible

All of the above

52 / 71

the typedef has the advantage that they obey scope rules, that is they can be declared local to a function or a block whereas #define always had a global effect.

True

False

53 / 71

In the statement expression1 >> expression2. if expression1 is a signed integer with its leftmost bit set to 1 then on right shifting it the result of the statement will vary from computer to computer

True

False

54 / 71

In a C program snippet, the following are used for the definition of Integer variables?

int s;

unsigned u;

long l;

long long ll;

Pick the best statement for these.

All of the above variable definitions are incorrect because basic data type int is missing.

All of the above variable definitions are correct because int is implicitly assumed in all of these.

Only “long l;” and “long long ll;” are valid definitions of variables.

Only “unsigned u;” is valid definition of variable.

Please note that signed, unsigned and long all three are Type specifiers. And int is implicitly assumed in all of three. As per C standard, “int, signed, or signed int” are equivalent. Similarly, “unsigned, or unsigned int” are equivalent. Besides, “long, signed long, long int, or signed long int” are all equivalent. And “long long, signed long long, long long int, or signed long long int“ are equivalent.

55 / 71

Let arr is an array. Which of the following are illegal

arr++

arr+1

arr+2

None of the above

56 / 71

A program attempts to generate as many permutations as possible of the string, 'abcd' by pushing the characters a, b, c, d in the same order onto a stack, but it may pop off the top character at any time. Which one of the following strings CANNOT be generated using this program?

abcd

dcba

cbad

cabd

A. PUSH a- POP a , PUSH b- POP b , PUSH c- POP c, PUSH d- POP d B. PUSH a ,PUSH b, PUSH c,PUSH d , POP d, POP c ,POP b, POP a C.PUSH a ,PUSH b, PUSH c , POP c ,POP b, POP a PUSH d- POP d D. Sequence not feasible Therefore,Answer is D

57 / 71

i) sizeof(int);
ii) sizeof(int*);
iii) sizeof(int**);

Assuming size of pointer is 4 bytes and size of int is also 4 bytes, pick the most correct answer from the given options.

Only i) would compile successfully and it would return size as 4.

i), ii) and iii) would compile successfully and size of each would be same i.e. 4

i), ii) and iii) would compile successfully but the size of each would be different and would be decided at run time.

ii) and iii) would result in compile error but i) would compile and result in size as 4.

58 / 71

Is this the correct way for the NULL pointer assignment?

int i=0;
char *q=(char*)i;

No

Yes

59 / 71

Pick the correct statement for const and volatile.

const is the opposite of volatile and vice versa.

const and volatile can’t be used for struct and union.

const and volatile can’t be used for enum.

const and volatile can’t be used for typedef.

const and volatile are independent i.e. it’s possible that a variable is defined as both const and volatile.

In C, const and volatile are type qualifiers and these two are independent. Basically, const means that the value isn’t modifiable by the program. And volatile means that the value is subject to sudden change (possibly from outside the program). In fact, C standard mentions an example of valid declaration which is both const and volatile. The example is “extern const volatile int real_time_clock;” where real_time_clock may be modifiable by hardware, but cannot be assigned to, incremented, or decremented. So we should already treat const and volatile separately. Besides, these type qualifier applies for struct, union, enum and typedef as well.

60 / 71

Which Keyword is used to prevent any changes in the value of the variable

static

const

extern

inline

61 / 71

Which of the following are correctly formed #define statements in C?

#define CUBE (X) (X*X*X);

#define CUBE(X) (X*X*X)

#define CUBE(x) (X*X*X)

#define CUBE(X) {X*X*X}

62 / 71

Which of the following is correct with respect to “Jump Statements” in C?

goto

continue

break

return

All of the above.

As per C standard, “A jump statement causes an unconditional jump to another place”. So if we see carefully, all “goto”, “continue”, “break” and “return” makes the program control jump unconditionally from one place to another. That’s why correct answer is E.

63 / 71

Syntax of accessing the seventh element from the array in C.

Note: Array 0th position element is the first element.

a[6]

a{6}

a<6>

a"6"

64 / 71

What is the similarity between a structure, union, and enumeration?

All of them let you define new pointers

All of them let you define new data types

All of them let you define new values

All of them let you define new structures

65 / 71

Are logical operator sequence points?

Depends on functions

Depends on standards

False

True

66 / 71

Which of the following symbol is used in the variable name?

@

#

-

_

67 / 71

Let x be an integer which can take a value of 0 or 1. The statement if(x = =0) x = 1; else x = 0; is equivalent to which one of the following?

x = 1 + x;

x = 1 - x;

x = x - 1;

x = 1 % x;

68 / 71

Are the properties of i, j and x, y in the following program same?

typedef unsigned long int uli; uli i, j;

unsigned long int x, y;

Yes

No

69 / 71

Choose the correct statements

An array size can not changed once it is created.

Array element value can be changed any number of times

To access Nth element of an array students, use students[n-1] as the starting index is 0.

All of these

70 / 71

Which one is not a logical or relational operator?

||

&&

==

=

71 / 71

Is there any difference between the two statements?
char *ch = "Aticleworld";
char ch[] = "Aticleworld";

Yes

No

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C MCQ: C Multiple Choice Questions And Answers

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