Top interview questions in c
- 1. Visionard Humans + Technology = Great Combination Top interview questions in C Duration 1 Hour Difficulty Level Beginner Visionard, your learning partner 1
- 2. Question 1 What are the features of C language? Answer C language has many inbuilt features such as ● It combines features of assembly language and high level language. ● Easy to program - C languages has data types and different operators, which makes easier to write complex program ● Portable - Program written on C are portable, hence can be used in other computer with no modification ● Easy to extends - You can easily create your own functions and libraries in C language. ● Very fast - Program written in c are very fast to run with no delay ● Rich set of libraries - C languages has rich set of libraries, which makes coding complex program easier. Question 2 What is the difference between source code and object code? Answer Source code is the code which is written by the programmer, it consists of all the functions, conditional statements and libraries. Only a human being can read this code while computer cannot read this code. Source code extension in c language is .c Object code when you compile the source code, you get the object code. The format of the code is only computer readable. Object code extension in language is .obj Visionard, your learning partner 2
- 3. Question 3 What is the difference between = and == ? Answer = is also known as assignment operator which is used to assign a value to the variable == is also known as comparison operator which is used to compare two values in a conditional statement. Question 4 What is a header file and why we need header file in C program? Answer A header file are also known as library. They contain definition and prototype of the inbuilt functions. Header files have .h as their file extension. We need header files so, we can use functions which are inbuilt within the language. Example studio.h contains functions like printf() Question 5 What is the difference between syntax error, run-time error and logical error? Answer Syntax error occurs when we make mistakes in the syntax of c program. This error is shown when we try to compile our program, so it is also known as compile time error. Example ● A missing semicolon Visionard, your learning partner 3
- 4. Run-time error occurs during the execution of our program after successful compilation. A compiler cannot find them so they are very hard to find, as they only occur during the run time of the program. Example ● Dividing a number with 0 Logical Error occurs when you get different output based on the input. Major cause of this error is logic created by the programmer. They are again hard to find and cannot be detected by the compiler. Example ● A sum of 2 number returning a negative value. Question 6 Why C language is known as middle level language? OR What type of language is C language? Low level, middle level or high level? Answer C language is known as middle level language because it can access machine level(low level) features like accessing structure of the memory just like assembly language. But also acts as high level language in which you can use english language to write your program. Visionard, your learning partner 4
- 5. Question 7 What is the difference between i++ and ++i? OR What is the difference between post increment operator and pre increment operator? Answer Post increment operator or i++ In this, we first assign the value and then increment the value by one Pre increment operator or ++i In this, we first increment the value by one and then assign the value. Question 8 What is the difference between actual parameters and formal parameters? Answer Actual Parameters are passed when you call the function in your program. Formal Parameters are parameters which are given in the prototype and definition of the function. Visionard, your learning partner 5
- 6. Question 9 What are different data types in C language? Answer There are 4 basic data types in c ● Int - size 4 byte ● char - size 1 byte ● float - size 4 byte ● double - size 4 byte Question 10 What are pointers in C? Answer Pointers are types of variables which are used to store address of another variable. They can only store address of variables of similar data type Question 11 What are modifiers in language c? Explain different types of modifiers? Answer Modifiers are used to increase or decrease the size in memory and range of a variable. They are prefixed before the data type of the variable. Different types of modifiers in language c are ● short ● long ● signed ● Unsigned Visionard, your learning partner 6
- 7. Example ● short int age = 5; ● long int value = 10000; Question 12 What are arrays? Why we need array? Explain different types of array! Answer An array are collection of similar data types. We need array for the following reason ● Allocates contiguous block of memory ● Makes our program efficient ● Good to use when we have more than 1 variable of similar data types Types of array ● Single dimension array or 1D array - they consists of just 1 row of similar data types ● Multidimensional array consists of x rows and y columns of similar data types. Question 13 What is the difference between call by value and call by reference? Explain with example! Answer Call by Value when you pass the copy of variable in the function call, it is known as call by value. In this method, any modification whatsoever are done in the duplicate copy of the variable. Visionard, your learning partner 7
- 8. Call by reference when you pass original value of the variable in the function call, it is also known as call by reference. In this method, any modification whatsoever are done in the original variable hence the changes are reflected in the original variable. Question 14 What is stack? Answer Stack is a type of data structure which works on the principle of Last in first out(LIFO). Storing the data inside a stack is known as push while removing the data from stack is pop. Question 15 What is queue? Answer A queue is the type of data structure which works on the principle of First in first out(FIFO). The order of data insertion and deletions is on FIFO. Question 16 What are linked list? Answer A linked list is type of data structure where current node is connected to the previous node. A basic linked list block consists of 2 part 1) Previous address - this part contains the address of previous node 2) Value - this part stores the value in the current node. Linked list are of 2 types Visionard, your learning partner 8
- 9. 1. Singly Linked List 2. Doubly Linked List Singly Linked list - It consists of only 2 part, previous address part to store address of previous block and data part to store the data. Doubly Linked List - It consists of 3 parts, previous address part to store address of previous block, data part to store the data and next address part to store the address of next block. Question 17 What is dynamic memory allocation? Answer When you allocate memory during the run time of the program, it is known as dynamic memory allocation. There are 4 basic functions for dynamic memory allocation ● malloc() ● calloc() ● free ● Realloc These functions can be found in stdlib.h header file Question 18 What is the difference between a structure and union? Answer Union is user defined data type, which combines more than one data types as a single entity. The size of union is the size of the biggest data type inside that union Structure is a user defined data type, which combines more than one data types as a single entity. The size of structure is equal to the sum of all data types inside the structure. Visionard, your learning partner 9
- 10. Question 19 Explain why c language is a case sensitive language with an example! Answer C language is a case sensitive language because variable names with different cases are different from each other. Example of different variables with same name but capital letter and small letters combination ● Age is different from ● aGE which is different from ● AGe which is different from ● agE which is different from ● aGe which is different from ● AgE which is different from ● age which is different from AGE Question 20 What is the difference between local variables and global variables? Answer Local variable are variables with scope limited to the block of code, if a variable is declared inside the function, you can only access it inside the function. You cannot access local variables from outside the function. Global variable are variables with scope throughout the program. You can access the variable from any function or any block of code within the program. Visionard, your learning partner 10