top 100 c interview questions and answers

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TOP 100INTERVIEW QUESTIONS & ANSWERS

C

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Who invented C Language?

2

QUESTION

Dennis Ritchie in 1972 developed a new language by inheriting the features of both BCPL and B and adding

additional features. He named the language as just C

ANSWER

QUESTION 1

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What are the features of C Langauges?

3

QUESTION

• In C one can write programs like that of high level languages as in COBOL, BASIC, FORTRAN etc. as well as it

permits very close interaction with the inner workings of the computer.

• It is a general purpose programming language. It is usually called system programming language but equally

suited to writing a variety of applications.

• It supports various data types

• It follows the programming style based on fundamental control flow constructions for structured programming

• Functions may be pre–defined or user defined and they may return values of basic types, structures, unions or

pointers

ANSWER

QUESTION 2



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What are the advantages of c language?

4

QUESTION

• Easy to write

• Rich set of operators and functions that are built–in

• Support for bit–wise operation

• Flexible use of pointers

• Direct control over the hardware

• Ability to access BIOS/DOS routines

• Interacting using Interrupts

• Ability to write TSR programs

• Ability to create .COM files

• Ability to create library files (.LIB)

• Ability to write interface programs

• Incorporating assembly language in C program

ANSWER

QUESTION 3



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What is a header file?

5

QUESTION

Header files provide the definitions and declarations for the library functions. Thus, each header file contains the

library functions along with the necessary definitions and declarations. For example, stdio.h, math.h, stdlib.h,

string.h etc.

ANSWER

QUESTION 4



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List the different types of C tokens?

6

QUESTION

• Constants

• Identifiers

• Keywords

• Operators

• Special symbols

• Strings

ANSWER

QUESTION 5



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What is a constant? What are the different types of constants?

7

QUESTION

A constant is a value that does not change during the program execution. A constant used in C does not occupy

memory. There are five types of constants. They are:

• Integer constants

• Floating point constants

• Character constants

• String literals

• Enumeration constants

ANSWER

QUESTION 6



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What are the different types of c instructions?

8

QUESTION

• There are basically three types of instructions in C are :

• Type Declaration Instruction

• Arithmetic Instruction

• Control Instruction

ANSWER

QUESTION 7



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Why C is called a middle level language?

9

QUESTION

C combines the features of both Assembly Level Languages (Low Level Languages) and Higher Level Languages.

For this reason, C is referred to as a Middle Level Language. The feature of ALLs is that of enabling us to develop

system level programs and the features of HLLs are those of higher degree of readability and machine

independence.

ANSWER

QUESTION 8



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What is the purpose of main() function?

10

QUESTION

• The function main() invokes other functions within it. It is the first function to be called when the program starts

execution.

• It is the starting function.

• It returns an int value to the environment that called the program.

• Recursive call is allowed for main( ) also.

• It is a user-defined function.

ANSWER

QUESTION 9



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What is meant by type specifiers?

11

QUESTION

Type specifiers decide the amount of memory space occupied by a variable. In the ease of integral types; it also

explicitly states the range of values that the object can hold.

ANSWER

QUESTION 10



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What is the difference between single charater constant and string constant?

12

QUESTION

• A single character constant consists of only one character and it is enclosed within a pair of single quotes.

• A string constant consists of one or more characters and it is enclosed within a pair of double quotes.

ANSWER

QUESTION 11



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What is a loop?

13

QUESTION

A loop is a process to do a job repeatedly with possibly different data each time. The statements executed each time

constitute the loop body, and each pass is called iteration. A condition must be present to terminate the loop.

ANSWER

QUESTION 12



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What are the types of data types and explain?

14

QUESTION

There are five basic Data types in C. These are :

• void: means nothing i.e. no data involvement in an action

• char: to work with all types of characters used in computer operations

• int: to work with an integer type of data in any computational work

• float: to work with the real type of data or scientific numbers in the exponential form

• double: to work with double precision of numbers when the approximation is very crucial.

ANSWER

QUESTION 13



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What is the general form of a C program?

15

QUESTION

A C program begins with the preprocessor directives, in which the programmer would specify which header file and

what constants (if any) to be used. This is followed by the main function heading. Within the main function lies the

variable declaration and program statement.

ANSWER

QUESTION 14



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What is the difference between Call by Value and Call by Reference?

16

QUESTION

When using Call by Value, you are sending the value of a variable as parameter to a function, whereas Call by

Reference sends the address of the variable. Also, under Call by Value, the value in the parameter is not affected

by whatever operation that takes place, while in the case of Call by Reference, values can be affected by the

process within the function.

ANSWER

QUESTION 15



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What is a stack?

17

QUESTION

A stack is one form of a data structure. Data is stored in stacks using the FILO (First In Last Out) approach. At any

particular instance, only the top of the stack is accessible, which means that in order to retrieve data that is stored

inside the stack, those on the upper part should be extracted first. Storing data in a stack is also referred to as a

PUSH, while data retrieval is referred to as a POP.

ANSWER

QUESTION 16



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What is the use of a „\0′ character?

18

QUESTION

It is referred to as a terminating null character, and is used primarily to show the end of a string value.

ANSWER

QUESTION 17



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What is the difference between the = symbol and == symbol?

19

QUESTION

The = symbol is often used in mathematical operations. It is used to assign a value to a given variable. On the other

hand, the = = symbol, also known as “equal to” or “equivalent to”, is a relational operator that is used to compare

two values

ANSWER

QUESTION 18



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What is the modulus operator?

20

QUESTION

The modulus operator outputs the remainder of a division. It makes use of the percentage (%) symbol. For example:

10 % 3 = 1, meaning when you divide 10 by 3, the remainder is 1.

ANSWER

QUESTION 19



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Which of the following operators is incorrect and why? ( >=, <=, <>, ==)

21

QUESTION

<> is incorrect. While this operator is correctly interpreted as “not equal to” in writing conditional statements, it is not

the proper operator to be used in C programming. Instead, the operator != must be used to indicate “not equal

to” condition.

ANSWER

QUESTION 20



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What is syntax error?

22

QUESTION

Syntax errors are associated with mistakes in the use of a programming language. It maybe a command that was

misspelled or a command that must was entered in lowercase mode but was instead entered with an upper case

character. A misplaced symbol, or lack of symbol, somewhere within a line of code can also lead to syntax error.

ANSWER

QUESTION 21



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Can I use “int” data type to store the value 32768? Why?

23

QUESTION

No. “int” data type is capable of storing values from -32768 to 32767. To store 32768, you can use “long int” instead.

You can also use “unsigned int”, assuming you don‟t intend to store negative values.

ANSWER

QUESTION 22



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When is the “void” keyword used in a function?

24

QUESTION

When declaring functions, you will decide whether that function would be returning a value or not. If that function will

not return a value, such as when the purpose of a function is to display some outputs on the screen, then “void” is

to be placed at the leftmost part of the function header. When a return value is expected after the function

execution, the data type of the return value is placed instead of “void”.

ANSWER

QUESTION 23



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What is the significance of an algorithm to C programming?

25

QUESTION

Before a program can be written, an algorithm has to be created first. An algorithm provides a step by step

procedure on how a solution can be derived. It also acts as a blueprint on how a program will start and end,

including what process and computations are involved.

ANSWER

QUESTION 24



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How do you generate random numbers in C?

26

QUESTION

Random numbers are generated in C using the rand() command. For example: anyNum = rand() will generate any

integer number beginning from 0, assuming that anyNum is a variable of type integer.

ANSWER

QUESTION 25



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What is debugging?

27

QUESTION

Debugging is the process of identifying errors within a program. During program compilation, errors that are found

will stop the program from executing completely. At this state, the programmer would look into the possible

portions where the error occurred. Debugging ensures the removal of errors, and plays an important role in

ensuring that the expected program output is met.

ANSWER

QUESTION 26



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What does the && operator do in a program code?

28

QUESTION

The && is also referred to as AND operator. When using this operator, all conditions specified must be TRUE before

the next action can be performed. If you have 10 conditions and all but 1 fails to evaluate as TRUE, the entire

condition statement is already evaluated as FALSE.

ANSWER

QUESTION 27



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What is || operator and how does it function in a program?

29

QUESTION

The || is also known as the OR operator in C programming. When using || to evaluate logical conditions, any

condition that evaluates to TRUE will render the entire condition statement as TRUE.

ANSWER

QUESTION 28



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What will be the outcome of the following conditional statement if the value of

variable s is 10? s >=10 && s < 25 && s!=12

30

QUESTION

The outcome will be TRUE. Since the value of s is 10, s >= 10 evaluates to TRUE because s is not greater than 10

but is still equal to 10. s< 25 is also TRUE since 10 is less then 25. Just the same, s!=12, which means s is not

equal to 12, evaluates to TRUE. The && is the AND operator, and follows the rule that if all individual conditions

are TRUE, the entire statement is TRUE.

ANSWER

QUESTION 29



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What is FIFO?

31

QUESTION

In C programming, there is a data structure known as queue. In this structure, data is stored and accessed using

FIFO format, or First-In-First-Out. A queue represents a line wherein the first data that was stored will be the first

one that is accessible as well.

ANSWER

QUESTION 30



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In C language, the variables NAME, name, and Name are all the same. TRUE or

FALSE?

32

QUESTION

FALSE. C language is a case sensitive language. Therefore, NAME, name and Name are three uniquely different

variables.

ANSWER

QUESTION 31



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When is a “switch” statement preferable over an “if” statement?

33

QUESTION

The switch statement is best used when dealing with selections based on a single variable or expression. However,

switch statements can only evaluate integer and character data types.

ANSWER

QUESTION 32



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What is gets() function?

34

QUESTION

The gets() function allows a full line data entry from the user. When the user presses the enter key to end the input,

the entire line of characters is stored to a string variable. Note that the enter key is not included in the variable, but

instead a null terminator \0 is placed after the last character.

ANSWER

QUESTION 33



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Difference between Syntax and logical error?

35

QUESTION

Syntax error:

These involves validation of syntax of language

Compiler prints diagnostic message.

Logical error:

Logical error are caused by an incorrect algorithm or by a statement mistyped in such a way that it doesn‟t violet

syntax of language.

It is difficult to find.

ANSWER

QUESTION 34



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What is static memory allocation?

36

QUESTION

Compiler allocates memory space for a declared variable. By using the address of operator, the reserved address is

obtained and this address is assigned to a pointer variable. This way of assigning pointer value to a pointer

variable at compilation time is known as static memory allocation.

ANSWER

QUESTION 35



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What is dynamic memory allocation?

37

QUESTION

A dynamic memory allocation uses functions such as malloc() or calloc() to get memory dynamically. If these

functions are used to get memory dynamically and the values returned by these function are assigned to pointer

variables, such a way of allocating memory at run time is known as dynamic memory allocation.

ANSWER

QUESTION 36



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Are Pointers Integer?

38

QUESTION

No, Pointers are not integers. A pointer is an address. It is a positive number.

ANSWER

QUESTION 37



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In header files whether functions are declared or defined?

39

QUESTION

Functions are declared within header file. That is function prototypes exist in a header file, not function bodies. They

are defined in library (lib).

ANSWER

QUESTION 38



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Difference between strdup and strcpy?

40

QUESTION

Both copy a string. Strcpy wants a buffer to copy into. Strdup allocates a buffer using malloc(). Unlike strcpy(),

strdup() is not specified by ANSI.

ANSWER

QUESTION 39



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What is spaghetti programming?

41

QUESTION

Spaghetti programming refers to codes that tend to get tangled and overlapped throughout the program. This

unstructured approach to coding is usually attributed to lack of experience on the part of the programmer.

Spaghetti programing makes a program complex and analyzing the codes difficult, and so must be avoided as

much as possible.

ANSWER

QUESTION 40



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In C programming, how do you insert quote characters („ and “) into the output

screen?

42

QUESTION

This is a common problem for beginners because quotes are normally part of a printf statement. To insert the quote

character as part of the output, use the format specifiers‟ (for single quote), and ” (for double quote).

ANSWER

QUESTION 41



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What is a nested loop?

43

QUESTION

A nested loop is a loop that runs within another loop. Put it in another sense, you have an inner loop that is inside an

outer loop. In this scenario, the inner loop is performed a number of times as specified by the outer loop. For each

turn on the outer loop, the inner loop is first performed.

ANSWER

QUESTION 42



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Can the curly brackets { } be used to enclose a single line of code?

44

QUESTION

While curly brackets are mainly used to group several lines of codes, it will still work without error if you used it for a

single line. Some programmers prefer this method as a way of organizing codes to make it look clearer, especially

in conditional statements.

ANSWER

QUESTION 43



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What are compound statements?

45

QUESTION

Compound statements are made up of two or more program statements that are executed together. This usually

occurs while handling conditions wherein a series of statements are executed when a TRUE or FALSE is

evaluated. Compound statements can also be executed within a loop. Curly brackets { } are placed before and

after compound statements.

ANSWER

QUESTION 44



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What is a register variable?

46

QUESTION

Register variables are stored in the CPU registers. Its default value is a garbage value. Scope of a register variable

is local to the block in which it is defined. Lifetime is till control remains within the block in which the register

variable is defined. Variable stored in a CPU register can always be accessed faster than the one that is stored in

memory. Therefore, if a variable is used at many places in a program, it is better to declare its storage class as

register

Example: register int x=5;

Variables for loop counters can be declared as register. Note that register keyword may be ignored by some

compilers.

ANSWER

QUESTION 45



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What is size of void pointer?

47

QUESTION

Size of any type of pointer in c is independent of data type which is pointer is pointing i.e. size of all type of pointer

(near) in c is two byte either it is char pointer, double pointer, function pointer or null pointer. Void pointer is not

exception of this rule and size of void pointer is also two byte.

ANSWER

QUESTION 46



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What are printf and scanf, call by reference or call by value?

48

QUESTION

Printf : Call by value

Scanf : Call by reference

ANSWER

QUESTION 47



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What is a const pointer?

49

QUESTION

a const pointer means the pointer which represents the address of one value. so if you declare a pointer inside the

function, it doesn't have scope outside the function. if it is also available to the outside function whenever we

declare a pointer as const.

ANSWER

QUESTION 48



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Why does n++ execute much faster than n+1?

50

QUESTION

n++ takes more than one instruction, ++n is faster. n++ has to store n, increment the variable and return n, while

++n increment n and return without storing the previous value of n.

ANSWER

QUESTION 49



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What is modular Programming?

51

QUESTION

If a program is large, it is subdivided into a number of smaller programs that are called modules or subprograms. If a

complex problem is solved using more modules, this approach is known as modular programming.

ANSWER

QUESTION 51



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Why doesn't C support function overloading?

52

QUESTION

Overloading is polymorphism which is one of the characteristics of Object oriented programming. C is not and object

oriented language like C++ or Java. Therefore, no overloading, inheritance, etc.

ANSWER

QUESTION 51



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What is an incomplete type?

53

QUESTION

Incomplete types refers to pointers in which there is non availability of the implementation of the referenced location

or it points to some location whose value is not available for modification.

ANSWER

QUESTION 52



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Explain the Difference between C and C++?

54

QUESTION

C is the predecessor of C++. C++ is an Object Oriented, non-procedural language, unlike C, which is a procedural

language. C++ treats all data and functional handling in terms of Objects and their relationships.

ANSWER

QUESTION 53



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What is Nesting in C?

55

QUESTION

Including one constructed inside another, is nesting. Nesting can be a structure inside another structure, an if-else

statement within another, multiple while loops, one inside the other. Continuing our earlier example, if you have a

collection of bikes, instead of grouping them separately, you can nest them within a main structure, which you can

name “Collection of Bikes”.

ANSWER

QUESTION 54



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How is calloc () different from malloc ()?

56

QUESTION

The main difference between the two is that calloc (), when it is used to assign a block of memory, the allocated

contents are initialized to 0. Malloc (), on the other hand, does not initialise the memory block it assigns. The

memory just has random values left over from previous usage.

ANSWER

QUESTION 55



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What are Destructors in C Language?

57

QUESTION

Classifying a destructor you can call it a class object and it is called a destructor once it goes out of scope or gets

deleted overtly. The job of a destructor is to put an end to objects being produced by a constructor. Just like the

constructor you can consider destructor a functional member and it is specifically known by a class name.

ANSWER

QUESTION 56



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What are the uses of a pointer?

58

QUESTION

Pointer is used in the following cases

i) It is used to access array elements

ii) It is used for dynamic memory allocation.

iii) It is used in Call by reference

iv) It is used in data structures like trees, graph, linked list etc.

ANSWER

QUESTION 57



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What is a union?

59

QUESTION

Union is a collection of heterogeneous data type but it uses efficient memory utilization technique by allocating

enough memory to hold the largest member. Here a single area of memory contains values of different types at

different time. A union can never be initialized.

ANSWER

QUESTION 58



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What are macros? What are its advantages and disadvantages?

60

QUESTION

Macros are abbreviations for lengthy and frequently used statements. When a macro is called the entire code is

substituted by a single line though the macro definition is of several lines.

The advantage of macro is that it reduces the time taken for control transfer as in case of function.

The disadvantage of it is here the entire code is substituted so the program becomes lengthy if a macro is called

several times.

ANSWER

QUESTION 59



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What are enumerations?

61

QUESTION

They are a list of named integer-valued constants. Example:enum color { black , orange=4, yellow, green, blue,

violet }; This declaration defines the symbols “black”, “orange”, “yellow”, etc. to have the values “1,” “4,” “5,” … etc.

The difference between an enumeration and a macro is that the enum actually declares a type, and therefore can

be type checked.

ANSWER

QUESTION 60



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What is the use of typedef?

62

QUESTION

The typedef help in easier modification when the programs are ported to another machine. A descriptive new name

given to the existing data type may be easier to understand the code.

ANSWER

QUESTION 61



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What is the difference between Strings and Arrays?

63

QUESTION

String is a sequence of characters ending with NULL .it can be treated as a one dimensional array of characters

terminated by a NULL character.

ANSWER

QUESTION 62



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What is a normalized pointer, how do we normalize a pointer?

64

QUESTION

It is a 32bit pointer, which has as much of its value in the segment registered as possible. Since a segment can start

every 16bytes so the offset will have a value from 0 to F. for normalization convert the address into 20bit address

then use the 16bit for segment address and 4bit for the offset address. Given a pointer 500D: 9407, we convert it

to a 20bitabsolute address 549D7,Which then normalized to 549D:0007.

ANSWER

QUESTION 63



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What is generic pointer in C?

65

QUESTION

In C void* acts as a generic pointer. When other pointer types are assigned to generic pointer, conversions are

applied automatically (implicit conversion).

ANSWER

QUESTION 64



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Difference between linker and linkage?

66

QUESTION

Linker converts an object code into an executable code by linking together the necessary built in functions. The form

and place of declaration where the variable is declared in a program determine the linkage of variable.

ANSWER

QUESTION 65



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What is a function?

67

QUESTION

A large program is subdivided into a number of smaller programs or subprograms. Each subprogram specifies one

or more actions to be performed for the larger program. Such sub programs are called functions.

ANSWER

QUESTION 66



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What is an argument?

68

QUESTION

An argument is an entity used to pass data from the calling to a called function.

ANSWER

QUESTION 67



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Write a program which employs Recursion?

69

QUESTION

int fact(int n) { return n > 1 ? n * fact(n – 1) : 1; }

ANSWER

QUESTION 68



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What do the „c‟ and „v‟ in argc and argv stand for?

70

QUESTION

The c in argc(argument count) stands for the number of command line argument the program is invoked with and v

in argv(argument vector) is a pointer to an array of character string that contain the arguments.

ANSWER

QUESTION 69



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What are C identifiers?

71

QUESTION

These are names given to various programming element such as variables, function, arrays.It is a combination of

letter, digit and underscore.It should begin with letter. Backspace is not allowed.

ANSWER

QUESTION 70



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What do the functions atoi(), itoa() and gcvt() do?

72

QUESTION

atoi() is a macro that converts integer to character.

itoa() It converts an integer to string

gcvt() It converts a floating point number to string

ANSWER

QUESTION 71



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How is fopen() used ?

73

QUESTION

The function fopen() returns a file pointer. Hence a file pointer is declared and it is assigned as

FILE *fp;

fp= fopen(filename,mode);

filename is a string representing the name of the file and the mode represents:

“r” for read operation

“w” for write operation

“a” for append operation

“r+”,”w+”,”a+” for update operation

ANSWER

QUESTION 72



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What is the purpose of ftell ?

74

QUESTION

The function ftell() is used to get the current file represented by the file pointer.

ftell(fp);

returns a long integer value representing the current file position of the file pointed by the

file pointer fp.If an error occurs ,-1 is returned.

ANSWER

QUESTION 73



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Discuss on pointer arithmetic?

75

QUESTION

1. Assignment of pointers to the same type of pointers.

2. Adding or subtracting a pointer and an integer.

3. Subtracting or comparing two pointer.

4. Incrementing or decrementing the pointers pointing to the elements of an array. When a pointer to an integer is

incremented by one , the address is incremented by two. It is done automatically by the compiler.

5. Assigning the value 0 to the pointer variable and comparing 0 with the pointer. The pointer having address 0

points to nowhere at all.

ANSWER

QUESTION 74



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What is the invalid pointer arithmetic?

76

QUESTION

i) adding ,multiplying and dividing two pointers.

ii) Shifting or masking pointer.

iii) Addition of float or double to pointer.

iv) Assignment of a pointer of one type to a pointer of another type ?

ANSWER

QUESTION 75



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Can we initialize unions?

77

QUESTION

ANSI Standard C allows an initializer for the first member of a union. There is no standard way of initializing any

other member (nor, under a pre-ANSI compiler, is there generally any way of initializing a union at all).

ANSWER

QUESTION 76



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What is Output of following c snippet?

int main(){

char *s="Abhas";

printf("%s",s+ 2);

getch();

}

78

QUESTION

Has. Explanation: In the above program role of %s is to display the string whose address is passed as an

argument. This is how a standard printf statement works in c language. Now since we have passed s + 2 as an

argument therefore first value of this expression is evaluated. Here „s‟ would refer to address of first character in

string „s‟. Now printf would get address of third character (address of first character + 2) as argument so it will

display the string starting from third position. Hence output would be „has‟.

ANSWER

QUESTION 77



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What is difference between .com program and .exe program?

79

QUESTION

Both .com and .exe program are executable program but .com program executes faster than .exe program. All

drivers are .com program. .com file has higher preference than .exe.

ANSWER

QUESTION 78



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Describe turbo c Compiler?

80

QUESTION

Turbo c is an IDE programming language created by Borland. Turbo C 3.0 is based on MS DOS operation system. It

is one of the most popular c compilers. It uses 8086 microprocessor which is 16 bit microprocessor. It has 20

address buses and 16 data bus. Its word length is two byte.

ANSWER

QUESTION 79



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Out of fgets() and gets() which function is safe to use and why?

81

QUESTION

Fgets() is safer than gets(), because we can specify a maximum input length. Neither one is completely safe,

because the compiler can‟t prove that programmer won‟t overflow the buffer he pass to fgets ().

ANSWER

QUESTION 80



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Differentiate between a “for loop” and a “while loop”?

82

QUESTION

For executing a set of statements fixed number of times we use “for loop” while when the number of iterations to be

performed is not known in advance we use “while loop”.

ANSWER

QUESTION 81



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Is there a built-in function in C that can be used for sorting data?

83

QUESTION

Yes, use the qsort() function. It is also possible to create user defined functions for sorting, such as those based on

the balloon sort and bubble sort algorithm.

ANSWER

QUESTION 82



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What are the advantages and disadvantages of a heap?

84

QUESTION

Storing data on the heap is slower than it would take when using the stack. However, the main advantage of using

the heap is its flexibility. That‟s because memory in this structure can be allocated and remove in any particular

order. Slowness in the heap can be compensated if an algorithm was well designed and implemented.

ANSWER

QUESTION 83



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How do you convert strings to numbers in C?

85

QUESTION

You can write you own functions to do string to number conversions, or instead use C‟s built in functions. You can

use atof to convert to a floating point value, atoi to convert to an integer value, and atol to convert to a long integer

value.

ANSWER

QUESTION 84



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Create a simple code fragment that will swap the values of two variables num1 and

num2.

86

QUESTION

int temp;

temp = num1;

num1 = num2;

num2 = temp;

ANSWER

QUESTION 85



hirist.com

What is the use of a semicolon (;) at the end of every program statement?

87

QUESTION

It has to do with the parsing process and compilation of the code. A semicolon acts as a delimiter, so that the

compiler knows where each statement ends, and can proceed to divide the statement into smaller elements for

syntax checking.

ANSWER

QUESTION 86



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What does the characters “r” and “w” mean when writing programs that will make

use of files?

88

QUESTION

“r” means “read” and will open a file as input wherein data is to be retrieved. “w” means “write”, and will open a file

for output. Previous data that was stored on that file will be erased.

ANSWER

QUESTION 87



hirist.com

Which function in C can be used to append a string to another string?

89

QUESTION

The strcat function. It takes two parameters, the source string and the string value to be appended to the source

string.

ANSWER

QUESTION 88



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What is the difference between functions getch() and getche()?

90

QUESTION

Both functions will accept a character input value from the user. When using getch(), the key that was pressed will

not appear on the screen, and is automatically captured and assigned to a variable. When using getche(), the key

that was pressed by the user will appear on the screen, while at the same time being assigned to a variable.

ANSWER

QUESTION 89



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What does the function toupper() do?

91

QUESTION

It is used to convert any letter to its upper case mode. Toupper() function prototype is declared in <ctype.h>. Note

that this function will only convert a single character, and not an entire string.

ANSWER

QUESTION 90



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What are run-time errors?

92

QUESTION

These are errors that occur while the program is being executed. One common instance wherein run-time errors can

happen is when you are trying to divide a number by zero. When run-time errors occur, program execution will

pause, showing which program line caused the error.

ANSWER

QUESTION 91



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Is this program statement valid? INT = 10.50;

93

QUESTION

Assuming that INT is a variable of type float, this statement is valid. One may think that INT is a reserved word and

must not be used for other purposes. However, recall that reserved words are express in lowercase, so the C

compiler will not interpret this as a reserved word.

ANSWER

QUESTION 92



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What is wrong with this program statement? void = 10;

94

QUESTION

The word void is a reserved word in C language. You cannot use reserved words as a user-defined variable.

ANSWER

QUESTION 93



hirist.com

What would happen to X in this expression: X += 15; (assuming the value of X is 5)

95

QUESTION

X +=15 is a short method of writing X = X + 15, so if the initial value of X is 5, then 5 + 15 = 20.

ANSWER

QUESTION 94



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Not all reserved words are written in lowercase. TRUE or FALSE?

96

QUESTION

FALSE. All reserved words must be written in lowercase; otherwise the C compiler would interpret this as

unidentified and invalid.

ANSWER

QUESTION 95



hirist.com

What is floating point constants?

97

QUESTION

Floating-point constants are numbers with decimal parts. A floating-point constants consists of :

An integral part

A decimal point

A fractional part

An exponent part

An optional suffix

ANSWER

QUESTION 96



hirist.com

What is the difference between fread and fwrite function?

98

QUESTION

The fread() function returns the number of items read. This value may be less than count if the end of the file is

reached or an error occurs. The fwrite() function returns the number of items written. This value will equal count

unless an error occurs.

ANSWER

QUESTION 97



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What is meant by inheritance?

99

QUESTION

Inheritance is the process by which objects of one class acquire properties of objects of another class.

ANSWER

QUESTION 98



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What is a ternary operator in C?

100

QUESTION

Perhaps the most unusual operator in C language is one called the conditional expression operator. Unlike all other

operators in C which are either unary or binary operators the conditional expression operator is a ternary operator;

that is, it takes three operands. The two symbols that are used to denote this operator are the question mark (?)

and the colon (:). The first operand is placed before the ?, the second between the ? and the and the third after

the:.

ANSWER

QUESTION 99



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What is unary operator?

101

QUESTION

The operators that act upon a single operand to produce a new value are known as unary operators.

ANSWER

QUESTION 100



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Resources

102

http://www.fresherventure.net/frequently-asked-c-language-interview-questions-and-answers/http://www.itechaleart.com/2014/06/top-100-c-interview-qa.htmlhttp://placement.freshersworld.com/power-preparation/technical-interview-questions/C-programming-answers-21419http://career.guru99.com/top-100-c-interview-questions-answers/http://www.slideshare.net/vineetkumarsaini/top-c-language-interview-questions-and-answerhttp://www.cquestions.com/2010/10/c-interview-questions-and-answers.htmlhttp://placementsindia.blogspot.com/2007/10/basic-c-interview-questions.htmlhttps://www.udemy.com/blog/c-programming-questions/http://crackaninterview.com/c-language-interview-questions/http://www.cwithabhas.com/2013/09/simple-c-interview-questions-for-mass.htmlhttp://www.freejobalert.com/c-interview-questions/2891/


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TOP 100INTERVIEW QUESTIONS & ANSWERS

C

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