TCS Coding Questions

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TCS Coding Round Facts and Probabilities

TCS Coding Questions 2018 Changes of this TypeTime Difficulty Level
TCS Coding Round Questions on HCF LCM1018 -20 minsMedium
TCS Coding Test on Factorial and Series 2518 -20 minsHigh
Swapping and Reversal TCS Programming Questions 2018 -20 minsMedium – High
Number Operations 30 -3518 -20 minsHigh
Misc20 -2518 -20 minsMedium- High

Q1: What is the output of this C code?

#include <stdio.h>

void main()


int k = 5;

int *p = &k;

int **m = &p;

printf(“%d%d%d\n”, k, *p, **p);


a) 5 5 5

b) 5 5 junk

c) 5 junk junk

d) Compile time error

Q2. Which of the following statements about stdout and stderr are true?

a) They both are the same

b) Run time errors are automatically displayed in stderr

c) Both are connected to the screen by default.

d) stdout is line buffered but stderr is unbuffered.

Q3: Given the below statements about C programming language;

1) main() function should always be the first function present in a C program file

2) all the elements of an union share their memory location

3) A void pointer can hold address of any type and can be typcasted to any type

4) A static variable hold random junk value if it is not initialised

Which of the above are correct statements?

A) 2,3

B) 1,2

C) 1,2,3

D) 1,2,3,4

 Q4 If a function is defined as static, it means

A) The value returned by the function does not change

B) all the variable declared inside the function automatically will be assigned initial value of zero

C) It should be called only within the same source code / program file.

D) None of the other choices as it is wrong to add static prefix to a function

Q5: Comment on the below while statement

while (0 == 0) { }      

A) It has syntax error as there are no statements within braces {}

B) It will run forever

C) It compares 0 with 0 and since they are equal it will exit the loop immediately

D) It has syntax error as the same number is being compared with itself

 Section 4 Coding

Q1 : Write a C program to calculate the factorial of a non-negative integer N. The factorial of a number N is defined as the product of all integers from 1 up to N. Factorial of 0 is defined to be 1. The number N is a non-negative integer that will be passed to the program as the first command line parameter. Write the output to stdout formatted as an integer WITHOUT any other additional text. You may assume that the input integer will be such that the output will not exceed the largest possible integer that can be stored in an int type variable.

Q2: Write a C program to find the area of a triangle given the base and the corresponding height. The values base and height are both positive integers passed to the program as the first and second command line parameters respectively. Write the output to stdout formatted as a floating point number rounded to EXACTLY 2 decimal precision WITHOUT any other additional text. Scientific format(such as 1.00E+5) should NOT be used while printing the output. You may assume that the inputs will be such that the output will not exceed the largest possible real number that can be stored in a float type variable. 

Answer will be – 


1) It would have been 5 5 5 if it were **m and not **p.

2) a) False. b) Not by default. c) Not by default. d) True.

3) Only d) is False as static variables are initialised with 0.

4) Access to static functions is restricted to the file where they are declared. Therefore, when we want to restrict access to functions, we make them static. 5) while( 0==0) {} is equivalent to while(1) {} ———————————————————————————————————-


int main(int argc, char *argv[])


int n,f=1,i; n = atoi(argv[1]);

for( i = 1; i <=n ; ++i ) { f = f*i; } printf(“%d”,f);

return 0;

} ————————————————————————————————————-


int main(int argc, char *argv[])


int base = atoi(argv[1]);

int height = atoi(argv[2]);

float area = 0.5*base*height; printf(“%.2f”,area);

return 0;


These are some questions you should know the answers to. The underlined options are the correct ones.

Q1.A pointer variable can be

1. Changed within function.

2. Assigned an integer value.

3. None of these

4. Passed to a function as argument.

Q2. Which of the following uses structure?

1. Linked Lists

2. Array of structures

3. All of these

4. Binary Tree

Q3. Strings are character arrays. The last index of it contains the null-terminated character

1. \t

2. \1

3. \0

4. \n

Q4. Which of the following is a collection of different data types?

1. String

2. Structure

3. Array

4. Files

Q5. What function should be used to free the memory allocated by calloc() ?

1. free();

2. malloc(variable_name, 0)

3. dealloc();

4. memalloc(variable_name, 0)

Q6. In the standard library of C programming language, which of the following header file is designed for basic mathematical operations?

1. conio.h

2. stdio.h

3. math.h

4. dos.h

Q7. int **ptr; is?

1. Pointer to integer

2. None of these

3. Pointer to pointer

4. Invalid declaration

Q8. Which of the following special symbol allowed in a variable name?

1. (underscore)

2. – (hyphen)

3. | (pipeline)

4. * (asterisk)

Q9. All keywords in C are in

1. Uppercase letters

2. None of these

3. Lowercase letters

4. Camel Case letters

Q10. What should the program below print?

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

void myfunc(char** param){



int main(){

char* string = (char*)malloc(64);

strcpy(string, “hello_World”);



printf(“%s\n”, string);

// ignore memory leak for sake of quiz

return 0;


1. hello_World

2. ello_World

3. lo_World

4. llo_World

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

A. The element will be set to 0.

B. The compiler would report an error.

C. The program may crash if some important data gets overwritten.

D. The array size would appropriately grow.

Answer: Option C


If the index of the array size is exceeded, the program will crash. Hence “option c” is the correct answer. But the modern compilers will take care of this kind of errors.

2. What does the following declaration mean?

int (*ptr)[10];

A.ptr is array of pointers to 10 integers

B.ptr is a pointer to an array of 10 integers

C.ptr is an array of 10 integers

D.ptr is an pointer to array

Answer: Option B

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

A.Value of elements in array

B.First element of the array

C.Base address of the array

D.Address of the last element of array

Answer: Option C


The statement ‘C’ is correct. When we pass an array as a function argument, the base address of the array will be passed.

4. What will be the output of the program ?


int main()


    int a[5] = {5, 1, 15, 20, 25};

    int i, j, m;

    i = ++a[1];

    j = a[1]++;

    m = a[i++];

    printf(“%d, %d, %d”, i, j, m);

    return 0;


A.2, 1, 15             

B.1, 2, 5

C.3, 2, 15             

D.2, 3, 20

Answer: Option C


Step 1: int a[5] = {5, 1, 15, 20, 25}; The variable arr is declared as an integer array with a size of 5 and it is initiapzed to

a[0] = 5, a[1] = 1, a[2] = 15, a[3] = 20, a[4] = 25 .

Step 2: int i, j, m; The variable i,j,m are declared as an integer type.

Step 3: i = ++a[1]; becomes i = ++1; Hence i = 2 and a[1] = 2

Step 4: j = a[1]++; becomes j = 2++; Hence j = 2 and a[1] = 3.

Step 5: m = a[i++]; becomes m = a[2]; Hence m = 15 and i is incremented by 1(i++ means 2++ so i=3)

Step 6: printf(“%d, %d, %d”, i, j, m); It prints the value of the variables i, j, m

Hence the output of the program is 3, 2, 15

5. Is there any difference int the following declarations?

int fun(int arr[]);

int fun(int arr[2]);



Answer: Option B


No, both the statements are same. It is the prototype for the function fun() that accepts one integer array as an parameter and returns an integer value.

6. Are the expressions arr and &arr same for an array of 10 integers?



Answer: Option B


Both mean two different things. arr gives the address of the first int, whereas the &arr gives the address of array of ints.

7. Which of the fplowing statements should be used to obtain a remainder after dividing 3.14 by 2.1?

A.rem = 3.14 % 2.1;

B.rem = modf(3.14, 2.1);

C.rem = fmod(3.14, 2.1);

D.Remainder cannot be obtain in floating point division.

Answer: Option C


fmod(x,y) – Calculates x modulo y, the remainder of x/y.

This function is the same as the modulus operator. But fmod() performs floating point divisions.

8. What are the types of pnkages?

A.Internal and External

B.External, Internal and None

C.External and None     


Answer: Option B


External pnkage-> means global, non-static variables and functions.

Internal pnkage-> means static variables and functions with file scope.

None pnkage-> means Local variable

9. Which of the fplowing special symbp allowed in a variable name?

A.* (asterisk)    

B.| (pipepne)



Answer: Option D


Variable names in C are made up of letters (upper and lower case) and digits. The underscore character (“_”) is also permitted. Names must not begin with a digit.

Examples of vapd (but not very descriptive) C variable names:

=> foo

=> Bar

=> BAZ

=> foo_bar

=> _foo42

=> _

=> QuUx

10. Is there any difference between fplowing declarations?

1 : extern int fun();

2 : int fun();

A.Both are identical

B.No difference, except extern int fun(); is probably in another file fun(); is overrided with extern int fun();

D.None of these

Answer: Option B


extern int fun(); declaration in C is to indicate the existence of a global function and it is defined externally to the current module or in another file.

int fun(); declaration in C is to indicate the existence of a function inside the current module or in the same file.

Do tell us if you found these questions useful!

Here are the next set of questions for you! We will be posting 10 Technical questions everyday for your preparation. Happy learning!

Question 1:  How would you round off a value from 1.66 to 2.0?

A. ceil (1.66)
B. floor (1.66)
C. roundup (1.66)
D. Round to (1.66)

Answer: A

/* Example for ceil() and floor() functions: */



int main()


    printf(“\n Result : %f” , ceil(1.44) );

    printf(“\n Result : %f” , ceil(1.66) );

    printf(“\n Result : %f” , floor(1.44) );   

    printf(“\n Result : %f” , floor(1.66) );

    return 0;


// Output:

// Result : 2.000000

// Result : 2.000000

// Result : 1.000000

// Result : 1.000000

Question 2: What will be the output of the program?


int X=40;

int main()


    int X=20;

    printf(“%d\n”, X);

    return 0;





D.No Output

Answer:  A

Whenever there is conflict between a local variable and global variable, the local variable gets priority.

Question 3:  A long double can be used if range of a double is not enough to accommodate a real number.

A. True
B. False

Answer: A

True, we can use long double; if double range is not enough.

Double = 8 bytes. 
Long double = 10 bytes.

Question 4: A float is 4 bytes wide, whereas a double is 8 bytes wide.


B. False

Answer: A

float = 4 bytes. 
Double = 8 bytes.

Question 5: If the definition of the external variable occurs in the source file before its use in a particular function, then there is no need for an extern declaration in the function.

A. True
B. False
Answer: A

True, when a function is declared inside the source file, that function (local function) get a priority than the extern function. So there is no need to declare a function as extern inside the same source file

Question 6: If the definition of the external variable occurs in the source file before its use in a particular function, then there is no need for an extern declaration in the function.

A. True
B. False
Answer: A

True, When a function is declared inside the source file, that function(local function) get a priority than the extern function. So there is no need to declare a function as extern inside the same source file

Question 7: Size of short integer and long integer can be verified using the size of() operator.

A. True
B. False
Answer: A

True, we can find the size of short integer and long integer using the sizeof() operator.

Question 8: Range of double is -1.7e-38 to 1.7e+38 (in 16 bit platform – Turbo C under DOS)

A. True
B. False
Answer: B

False, the range of double is -1.7e-308 to 1.7e+308.

Question 9: Size of short integer and long integer would vary from one platform to another.

A. True
B. False
Answer: A

True, Depending on the operating system/compiler/system architecture you are working on, the range of data types can vary.

Question 10: Range of float id -2.25e-308 to 2.25e+308

A. True
B. False
Answer: Option B

False, the range of float is -3.4e-38 to 3.4e+38.

Set 4 – Technical questions. Read and learn!

Question 1: What is wrong in this statement? 



An ampersand ‘&’ symbol must be placed before the variable name whatnumber. Placing & means whatever integer value is entered by the user is stored at the “address” of the variable name. This is a common mistake for programmers, often leading to logical errors.

Question 2: What does the format %10.2 mean when included in a printf statement?


This format is used for two things: to set the number of spaces allotted for the output number and to set the number of decimal places. The number before the decimal point is for the allotted space, in this case it would allot 10 spaces for the output number. If the number of space occupied by the output number is less than 10, addition space characters will be inserted before the actual output number. The number after the decimal point sets the number of decimal places, in this case, it’s 2 decimal spaces.

 Question 3: What are linked list?


A linked list is composed of nodes that are connected with another. In C programming, linked lists are created using pointers. Using linked lists is one efficient way of utilizing memory for storage.

 Question 4: What are binary trees?


Binary trees are actually an extension of the concept of linked lists. A binary tree has two pointers, a left one and a right one. Each side can further branch to form additional nodes, which each node having two pointers as well.

Question 5: Differences between C and Java?


  1. JAVA is Object-Oriented while C is procedural.
    2. Java is an Interpreted language while C is a compiled language.
    3. C is a low-level language while JAVA is a high-level language.
    4. C uses the top-down approach while JAVA uses the bottom-up approach.
    5. Pointer goes backstage in JAVA while C requires explicit handling of pointers.

 Question 6: In header files whether functions are declared or defined?

Answer: Functions are declared within header file. That is function prototypes exist in a header file, not function bodies. They are defined in library (lib).

Question 7: What are the different storage classes in C?


There are four types of storage classes in C. They are extern, register, auto and static.

Question 8: What does static variable mean?


Static is an access qualifier. If a variable is declared as static inside a function, the scope is limited to the function, but it will exists for the life time of the program. Values will be persisted between successive calls to a function.

 Question 9: How do you print an address?


Use %p in printf to print the address.

Question 10: What are macros? What are its advantages and disadvantages?


Macros are processor directive which will be replaced at compile time.
The disadvantage with macros is that they just replace the code they are not function calls. Similarly the advantage is they can reduce time for replacing the same values.

Question 1: Difference between pass by reference and pass by value?


Pass by value just passes the value from caller to calling function so the called function cannot modify the values in caller function. But Pass by reference will pass the address to the caller function instead of value if called function requires to modify any value it can directly modify.

 Question 2: What is an object?


Object is a software bundle of variables and related methods. Objects have state and behaviour.

 Question 3: What is a class?


Class is a user-defined data type in C++. It can be created to solve a particular kind of problem. After creation the user need not know the specifics of the working of a class.

Question 4: What is the difference between class and structure?


Structure: Initially (in C) a structure was used to bundle different type of data types together to perform a particular functionality. But C++ extended the structure to contain functions also. 
The major difference is that all declarations inside a structure are by default public.
Class: Class is a successor of Structure. By default all the members inside the class are private.

 Question 5: What is pointer?


Pointer is a variable in a program is something with a name, the value of which can vary. The way the compiler and linker handles this is that it assigns 
a specific block of memory within the computer to hold the value of that variable.

 Question 6: What is the difference between null and void pointer?


 A Null pointer has the value 0. Void pointer is a generic pointer introduced by ANSI. Generic pointer can hold the address of any data type.

 Question 7: what is function overloading?


Function overloading is a feature of C++ that allows us to create multiple functions with the same name, so long as they have different parameters.Consider the following function:
   int Add(int nX, int nY)
      return nX + nY;

 Question 8: what is friend function?


A friend function for a class is used in object-oriented programming to allow access to public, private, or protected data in the class from the outside.
Normally, a function that is not a member of a class cannot access such information; neither can an external class. Occasionally, such access will be advantageous for the programmer. Under these circumstances, the function or external class can be declared as a friend of the class using the friend keyword

 Question 9: What do you mean by inline function?

Answer: The idea behind inline functions is to insert the code of a called function at the point where the function is called. If done carefully, this can improve the application’s performance in exchange for increased compile time and possibly (but not always) an increase in the size of the generated binary executables.

 Question 10: Tell me something about abstract classes?


An abstract class is a class which does not fully represent an object. Instead, it represents a broad range of different classes of objects. However, this representation extends only to the features that those classes of objects have in common. Thus, an abstract class provides only a partial description of its objects.

Question 1: What is the difference between an array and a list?


Array is collection of homogeneous elements. List is collection of heterogeneous elements.
For Array memory allocated is static and continuous. For List memory allocated is dynamic and random.
Array: User need not have to keep in track of next memory allocation.
List: User has to keep in Track of next location where memory is allocated.
Array uses direct access of stored members; list uses sequential access for members.

Question 2: What are the differences between structures and arrays?


Arrays are a group of similar data types but Structures can be group of different data types.

Question 3: What is data structure?


 A data structure is a way of organizing data that considers not only the items stored, but also their relationship to each other. Advance knowledge about the relationship between data items allows designing of efficient algorithms for the manipulation of data.

Question 4: Can you list out the areas in which data structures are applied extensively?


Compiler Design,
Operating System,
Database Management System,
Statistical analysis package,
Numerical Analysis,

Question 5: What are the advantages of inheritance?


It permits code reusability. Reusability saves time in program development. It encourages the reuse of proven and debugged high-quality software, thus reducing problem after a system becomes functional.

Question 6: Advantages of a macro over a function?


Macro gets to see the Compilation environment, so it can expand #defines. It is expanded by the pre-processor.

Question 7: What is command line argument?


Getting the arguments from command prompt in c is known as command line arguments. In c main function has three arguments. They are:

Argument counter
Argument vector
Environment vector

Question 8: What are the 4 basics of OOP? 


Abstraction, Inheritance, Encapsulation, and Polymorphism.

Question 9: Tell how to check whether a linked list is circular.


Create two pointers, each set to the start of the list. Update each as follows:
while (pointer1) {
pointer1 = pointer1->next;
pointer2 = pointer2->next; if (pointer2) pointer2=pointer2->next;
if (pointer1 == pointer2) {
print (“circular\n”);

Question 10:  Write a program to swap two numbers without using a temporary variable.


void swap(int &i, int &j)