SQL Interview Questions and Answers for Freshers pdf & Experienced Candidates

1. Which TCP/IP port does SQL Server run on? How can it be changed?

SQL Server runs on port 1433. It can be changed from the Network Utility TCP/IP properties.

2. What are the difference between clustered and a non-clustered index?

A clustered index is a special type of index that reorders the way records in the table are physically stored. Therefore table can have only one clustered index. The leaf nodes of a clustered index contain the data pages.
A non clustered index is a special type of index in which the logical order of the index does not match the physical stored order of the rows on disk. The leaf node of a non clustered index does not consist of the data pages. Instead, the leaf nodes contain index rows.
3. What are the different index configurations a table can have?

A table can have one of the following index configurations:

No indexes
A clustered index
A clustered index and many nonclustered indexes
A nonclustered index
Many nonclustered indexes
4. What are different types of Collation Sensitivity?

Case sensitivity - A and a, B and b, etc.
Accent sensitivity
Kana Sensitivity - When Japanese kana characters Hiragana and Katakana are treated differently, it is called Kana sensitive.
Width sensitivity - A single-byte character (half-width) and the same character represented as a double-byte character (full-width) are treated differently than it is width sensitive.
5. What is OLTP (Online Transaction Processing)?

In OLTP - online transaction processing systems relational database design use the discipline of data modeling and generally follow the Codd rules of data normalization in order to ensure absolute data integrity. Using these rules complex information is broken down into its most simple structures (a table) where all of the individual atomic level elements relate to each other and satisfy the normalization rules.

6. What's the difference between a primary key and a unique key?

Both primary key and unique key enforces uniqueness of the column on which they are defined. But by default primary key creates a clustered index on the column, where are unique creates a nonclustered index by default. Another major difference is that, primary key doesn't allow NULLs, but unique key allows one NULL only.


7. What is difference between DELETE and TRUNCATE commands?

Delete command removes the rows from a table based on the condition that we provide with a WHERE clause. Truncate will actually remove all the rows from a table and there will be no data in the table after we run the truncate command.

TRUNCATE:
TRUNCATE is faster and uses fewer system and transaction log resources than DELETE.
TRUNCATE removes the data by deallocating the data pages used to store the table's data, and only the page deallocations are recorded in the transaction log.
TRUNCATE removes all rows from a table, but the table structure, its columns, constraints, indexes and so on, remains. The counter used by an identity for new rows is reset to the seed for the column.
You cannot use TRUNCATE TABLE on a table referenced by a FOREIGN KEY constraint. Because TRUNCATE TABLE is not logged, it cannot activate a trigger.
TRUNCATE cannot be rolled back.
TRUNCATE is DDL Command.
TRUNCATE Resets identity of the table
DELETE:
DELETE removes rows one at a time and records an entry in the transaction log for each deleted row.
If you want to retain the identity counter, use DELETE instead. If you want to remove table definition and its data, use the DROP TABLE statement.
DELETE Can be used with or without a WHERE clause
DELETE Activates Triggers.
DELETE can be rolled back.
DELETE is DML Command.
DELETE does not reset identity of the table.
Note: DELETE and TRUNCATE both can be rolled back when surrounded by TRANSACTION if the current session is not closed. If TRUNCATE is written in Query Editor surrounded by TRANSACTION and if session is closed, it can not be rolled back but DELETE can be rolled back.

8. When is the use of UPDATE_STATISTICS command?

This command is basically used when a large processing of data has occurred. If a large amount of deletions any modification or Bulk Copy into the tables has occurred, it has to update the indexes to take these changes into account. UPDATE_STATISTICS updates the indexes on these tables accordingly.

9. What is the difference between a HAVING CLAUSE and a WHERE CLAUSE?

They specify a search condition for a group or an aggregate. But the difference is that HAVING can be used only with the SELECT statement. HAVING is typically used in a GROUP BY clause. When GROUP BY is not used, HAVING behaves like a WHERE clause. Having Clause is basically used only with the GROUP BY function in a query whereas WHERE Clause is applied to each row before they are part of the GROUP BY function in a query.

10. What are the properties and different Types of Sub-Queries?

Properties of Sub-Query
A sub-query must be enclosed in the parenthesis.
A sub-query must be put in the right hand of the comparison operator, and
A sub-query cannot contain an ORDER-BY clause.
A query can contain more than one sub-query.
Types of Sub-Query
Single-row sub-query, where the sub-query returns only one row.
Multiple-row sub-query, where the sub-query returns multiple rows,. and
Multiple column sub-query, where the sub-query returns multiple columns
11. What is SQL Profiler?

SQL Profiler is a graphical tool that allows system administrators to monitor events in an instance of Microsoft SQL Server. You can capture and save data about each event to a file or SQL Server table to analyze later. For example, you can monitor a production environment to see which stored procedures are hampering performances by executing too slowly.

Use SQL Profiler to monitor only the events in which you are interested. If traces are becoming too large, you can filter them based on the information you want, so that only a subset of the event data is collected. Monitoring too many events adds overhead to the server and the monitoring process and can cause the trace file or trace table to grow very large, especially when the monitoring process takes place over a long period of time.

12. What are the authentication modes in SQL Server? How can it be changed?

Windows mode and Mixed Mode - SQL and Windows. To change authentication mode in SQL Server click Start, Programs, Microsoft SQL Server and click SQL Enterprise Manager to run SQL Enterprise Manager from the Microsoft SQL Server program group. Select the server then from the Tools menu select SQL Server Configuration Properties, and choose the Security page.


13. Which command using Query Analyzer will give you the version of SQL server and operating system?

SELECT SERVERPROPERTY ('productversion'), SERVERPROPERTY ('productlevel'), SERVERPROPERTY ('edition').

14. What is SQL Server Agent?

SQL Server agent plays an important role in the day-to-day tasks of a database administrator (DBA). It is often overlooked as one of the main tools for SQL Server management. Its purpose is to ease the implementation of tasks for the DBA, with its full- function scheduling engine, which allows you to schedule your own jobs and scripts.

15. Can a stored procedure call itself or recursive stored procedure? How much level SP nesting is possible?

Yes. Because Transact-SQL supports recursion, you can write stored procedures that call themselves. Recursion can be defined as a method of problem solving wherein the solution is arrived at by repetitively applying it to subsets of the problem. A common application of recursive logic is to perform numeric computations that lend themselves to repetitive evaluation by the same processing steps. Stored procedures are nested when one stored procedure calls another or executes managed code by referencing a CLR routine, type, or aggregate. You can nest stored procedures and managed code references up to 32 levels.

16. What is Log Shipping?

Log shipping is the process of automating the backup of database and transaction log files on a production SQL server, and then restoring them onto a standby server. Enterprise Editions only supports log shipping. In log shipping the transactional log file from one server is automatically updated into the backup database on the other server. If one server fails, the other server will have the same db and can be used this as the Disaster Recovery plan. The key feature of log shipping is that it will automatically backup transaction logs throughout the day and automatically restore them on the standby server at defined interval.

17. Name 3 ways to get an accurate count of the number of records in a table?

SELECT * FROM table1
SELECT COUNT(*) FROM table1
SELECT rows FROM sysindexes WHERE id = OBJECT_ID(table1) AND indid < 2

18. What does it mean to have QUOTED_IDENTIFIER ON? What are the implications of having it OFF?

When SET QUOTED_IDENTIFIER is ON, identifiers can be delimited by double quotation marks, and literals must be delimited by single quotation marks. When SET QUOTED_IDENTIFIER is OFF, identifiers cannot be quoted and must follow all Transact-SQL rules for identifiers.


19. What is the difference between a Local and a Global temporary table?

A local temporary table exists only for the duration of a connection or, if defined inside a compound statement, for the duration of the compound statement.
A global temporary table remains in the database permanently, but the rows exist only within a given connection. When connection is closed, the data in the global temporary table disappears. However, the table definition remains with the database for access when database is opened next time.
20. What is the STUFF function and how does it differ from the REPLACE function?

STUFF function is used to overwrite existing characters. Using this syntax, STUFF (string_expression, start, length, replacement_characters), string_expression is the string that will have characters substituted, start is the starting position, length is the number of characters in the string that are substituted, and replacement_characters are the new characters interjected into the string. REPLACE function to replace existing characters of all occurrences. Using the syntax REPLACE (string_expression, search_string, replacement_string), where every incidence of search_string found in the string_expression will be replaced with replacement_string.

21. What is PRIMARY KEY?

A PRIMARY KEY constraint is a unique identifier for a row within a database table. Every table should have a primary key constraint to uniquely identify each row and only one primary key constraint can be created for each table. The primary key constraints are used to enforce entity integrity.

22. What is UNIQUE KEY constraint?

A UNIQUE constraint enforces the uniqueness of the values in a set of columns, so no duplicate values are entered. The unique key constraints are used to enforce entity integrity as the primary key constraints.

23. What is FOREIGN KEY?

A FOREIGN KEY constraint prevents any actions that would destroy links between tables with the corresponding data values. A foreign key in one table points to a primary key in another table. Foreign keys prevent actions that would leave rows with foreign key values when there are no primary keys with that value. The foreign key constraints are used to enforce referential integrity.

24. What is CHECK Constraint?

A CHECK constraint is used to limit the values that can be placed in a column. The check constraints are used to enforce domain integrity.


25. What is NOT NULL Constraint?

A NOT NULL constraint enforces that the column will not accept null values. The not null constraints are used to enforce domain integrity, as the check constraints.

26. How to get @@ERROR and @@ROWCOUNT at the same time?

If @@Rowcount is checked after Error checking statement then it will have 0 as the value of @@Recordcount as it would have been reset. And if @@Recordcount is checked before the error-checking statement then @@Error would get reset. To get @@error and @@rowcount at the same time do both in same statement and store them in local variable.

SELECT @RC = @@ROWCOUNT, @ER = @@ERROR
27. What is a Scheduled Jobs or What is a Scheduled Tasks?

Scheduled tasks let user automate processes that run on regular or predictable cycles. User can schedule administrative tasks, such as cube processing, to run during times of slow business activity. User can also determine the order in which tasks run by creating job steps within a SQL Server Agent job. E.g. back up database, Update Stats of Tables. Job steps give user control over flow of execution. If one job fails, user can configure SQL Server Agent to continue to run the remaining tasks or to stop execution.

28. What are the advantages of using Stored Procedures?

Stored procedure can reduced network traffic and latency, boosting application performance.
Stored procedure execution plans can be reused, staying cached in SQL Server's memory, reducing server overhead.
Stored procedures help promote code reuse.
Stored procedures can encapsulate logic. You can change stored procedure code without affecting clients.
Stored procedures provide better security to your data.
29. What is a table called, if it has neither Cluster nor Non-cluster Index? What is it used for?

Unindexed table or Heap. Microsoft Press Books and Book on Line (BOL) refers it as Heap. A heap is a table that does not have a clustered index and, therefore, the pages are not linked by pointers. The IAM pages are the only structures that link the pages in a table together. Unindexed tables are good for fast storing of data. Many times it is better to drop all indexes from table and then do bulk of inserts and to restore those indexes after that.

30. Can SQL Servers linked to other servers like Oracle?

SQL Server can be linked to any server provided it has OLE-DB provider from Microsoft to allow a link. E.g. Oracle has an OLE-DB provider for oracle that Microsoft provides to add it as linked server to SQL Server group.


31. What is BCP? When does it used?

BulkCopy is a tool used to copy huge amount of data from tables and views. BCP does not copy the structures same as source to destination. BULK INSERT command helps to import a data file into a database table or view in a user-specified format.

32. How to implement one-to-one, one-to-many and many-to-many relationships while designing tables?

One-to-One relationship can be implemented as a single table and rarely as two tables with primary and foreign key relationships. One-to-Many relationships are implemented by splitting the data into two tables with primary key and foreign key relationships. Many-to-Many relationships are implemented using a junction table with the keys from both the tables forming the composite primary key of the junction table.

33. What is an execution plan? When would you use it? How would you view the execution plan?

An execution plan is basically a road map that graphically or textually shows the data retrieval methods chosen by the SQL Server query optimizer for a stored procedure or ad- hoc query and is a very useful tool for a developer to understand the performance characteristics of a query or stored procedure since the plan is the one that SQL Server will place in its cache and use to execute the stored procedure or query. From within Query Analyzer is an option called "Show Execution Plan" (located on the Query drop-down menu). If this option is turned on it will display query execution plan in separate window when query is ran again.

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C Interview Questions and Answers For freshers pdf & Experienced Candidates

1) Who invented C Language?
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

2) Who invented B Language?
Ken Thomson at AT&T Bell Labs developed a language and named it B. Even the B language was found to have some short comings to support development of both business applications and system software.

3) Who invented BCPL Language?
Basic Combined Programming Language(BCPL) was developed by Martin Richards, Cambridge university.

4) Why C Language?
C is one of the high level languages. It is a general purpose language, which means it can be used to write programs of any sort.

5) What are the features of C Langauges?
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.

6)What are the advantages of c language?
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

7) What are the disadvantages of c langauge?
C is considered difficult to learn
Because of its conciseness, the code can be difficult to follow
It is not suited to applications that require a lot of report formatting and data file manipulation

8) What are the salient features of c languages?
The following are the salient features of C language are :
C is called a middle level language
C supports structured design approach
C is extensible
C is rich in data types and operators
C is portable

9) What is a header file?
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.

10) What is character set?
Character set is the set of characters allowed and supported in the programming language. Generally a program is a collection of instructions, which contain groups of characters. Only a limited set of characters is allowed to write instructions in the program.

11) What is C token?
The smallest individual units of a C program are known as tokens.

12) List the different types of C tokens?
Constants
Identifiers
Keywords
Operators
Special symbols
Strings

13) What is a string?
A string is a sequence of characters ending with NUL. It can be treated as a one–dimensional array of characters terminated by a NUL character.

14) What are qualifiers?
Qualifiers or modifiers are identifiers that may precede the scalar data types (except float) to specify the number of bits used for representing the respective type of data in memory. The qualifiers in C are short, long, signed, and unsigned.

15) What is a function?
A function is a set of statements to perform a specific task.

16) What is a constant?
A constant is a value that does not change during the program execution. A constant used in C does not occupy memory.

17) What are the different types of constants?
There are five types of constants. They are :
Integer constants
Floating point constants
Character constants
String literals
Enumeration constants

18) What is variable?
An identifier is used to identify and store some value. If the value of the identifier is changed during the execution of the program, then the identifier is known as variable.

19) What are the rules for the identifier?
The first character must be an alphabet or underscore (_)
Digits may be included in the variable
The maximum number of characters in a word are 32 (It may vary depending upon the platform)
No other special characters are allowed.

20) What are global variables?
Global Variables are those, which are required to be acccessed by all the functions defined after their declaration. So, the variables declared before the main {) can be acccessed by all the functions, which follow their declaration.

21) What is a keyword?
Keywords are those words of C which have predefined meaning assigned by the C language. They form a part of the database required by the C compiler.

22) What are the different types of c instructions?
There are basically three types of instructions in C are :
Type Declaration Instruction
Arithmetic Instruction
Control Instruction

23) What is an expression?
Expression is defined as a combination of operands and operators to obtain some computation. Operands represent variables or values and The operator tells is what operation to be performed.

24) What are the types of data files?
There are two types of data files :
stream oriented or standard data files
system oriented or low level data files

25) Why C is called a middle level language?
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.

26) How can variables be characterized?
The variables can be categorized by storage class as well as by data type. The storage class specifies the portion of the program within which the variables are recognized.

27) Give the rules for variable declaration?
The rules for variable declaration in C are given below :
A variable name consists of alphabets, digits and the underscore (_) character
The length of variable should be kept upto 8 characters though your system may allow upto 40 characters
They must begin with an alphabet
Some systems also recognize an underscore as the first character
White space and commas are not allowed
Any reserved word (keyword) cannot be used as a variable name.

28) What is the purpose of type declarations?
The type declaration allow to create a synonym for other data types. Its syntax is typedef type identifier; The declaration typedef unsigned long int INTEGER

29) What is recursion?
C language a function may call another function. When a function calls itself, it is referred to as recursive call and the process is known as recursion. C provides very good facilities for recursion.

30) What is data types?
Data types refer to the classes of data that can be manipulated by C programs. The three fundamental data types supported by C are character, integer and real type.

31) What are the types of macro formats?
There are two types of macro formats. There are
Simple
Parameterized

32) What are the different types of errors?
Compile–Time Errors
Linker Errors
Runtime Errors
Logical Errors

33) What is meant by errors and debugging?
Errors may be made during program creation even by experienced programmers. Such type of errors are detected by the compiler.
Debugging means removing the errors..

34) What is the purpose of main() function?
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.

35) What is meant by type casting?
It is the explicit type conversion required for a number before carrying out processing or assigning to another variable.

36) What are the primitive data types in c?
There are five different kinds of data types in C.
Char
Int
Float
Double
Void

37) What is the use of typedef?
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.

38) What is meant by type specifiers?
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..

39) What are the types of type specifiers?
The available data type specifiers are :
Short
Long
Signed
Unsigned

40) What is masking?
Masking is a process in which a given bit pattern is partly extracted into another bit pattern by means of a logical bitwise operation.

41) What is the difference between single character constant and string constant?
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.

42) What is signed and unsigned?
A numeric value, may have a positive or a negative sign. In the memory, for a variable, one bit is used exclusively to maintain the sign of the data. If we don't have sign, the sign bit also may be used for data. If the value is negative, the sign bit is 1, and if it is positive, it will be 0.

43) What are the different categories of functions in C?
In C, the functions can be divided into the following categories :
Functions with no arguments and no return values
Functions having arguments but no return values
Functions having arguments and return values also

44) What is this pointer?
It is a pointer that points to the current object. This can be used to access the members of the current object with the help of the arrow operator

45) What is zero based addressing?
The array subscripts always start at zero. The compiler makes use of subscript values to identify the elements in the array. Since subscripts start at 0, it is said that array uses zero-based addressing.

46) What is a loop?
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.

47) What are the types of data types and explain?
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.

48) What is friend function?
The function declaration should be preceded by the keyword friend.The function definitions does not use either the keyword or the scope operator ::. The functions that are declared with the keyword friend as friend function.Thus, a friend function is an ordinary function or a member of another class.

49) What is break statement?
When a break is encountered inside a loop, the loop is terminated and the control passes to the statement following the body of the loop.

50) What is the use of getchar() function?
It returns a character just entered from the standard input unit, that is, keyboard. The entered character can be either assigned to a character variable or echoed to the computer screen.


51) What is a pointer?
A pointer is a variable that represents the location (rather than the value) of a data item, such as a variable or an array element. It is a variable that holds a memory address. This address is the location of another variable or an array element in memory.

52) How to declare pointer variables?
If a variable is going to be a pointer, it must be declared as such. A pointer declaration consists of a base type, an *, and the variable name. The general form for declaring a pointer variable is data _type * var_ name;

53) What is the difference between fread buffer() and fwrite buffer()?
Fread(), buffer is a pointer to an area of memory that will receive the data from the file. For fwrite(), buffer is a pointer to the information that will be written to the file. The value of count determines how many items are read or written, with each item being num_byte bytes in length. The size_t in both the formats is defined as some kind of unsigned integer. Finally, fp is a file pointer to a previously opened file.

54) What is macro?
The second preprocessor function is macro definition. A macro is formal syntax that can be used to generate statements for use in a program. For the C language, the macro generates C statements.

55) What are the types of I/O functions?
I/O functions are grouped into two categories :
Unformatted I/O functions
Formatted I/O functions

56) What is the difference b/w formatted&unformatted I/O functions?
The formatted I/O functions allow programmers to specify the type of data and the way in which it should be read in or written out. On the other hand, unformatted I/O functions do not specify the type of data and the way is should be read or written.

57) How to declare pointer variables?
If a variable is going to be a pointer, it must be declared as such. A pointer declaration consists of a base type, an *, and the variable name. The general form for declaring a pointer variable is data _type * var_ name;

58) What is the difference between c &c++?
c++ is an object oriented programing but c is a procedure oriented programing.c is super set of c++. c can't suport inheritance,function overloading, method overloading etc. but c++ can do this.In c-programe the main function could not return a value but in the c++ the main function shuld return a value.

59) What is the use of putchar function?
The putchar function displays one character on the display monitor. The character to be displayed is of type char. The syntax for putchar function is as given below :putchar (ch_var);
Where ch_var is a previously declared character variable.

60) What is the use of getchar functions?
The getchar function accepts a single character from the keyboard. The function does not require any arguments, though a pair of empty parentheses must follow the word getchar as a syntax. It returns a single character from a standard input device (typically a keyboard ) and it can be assigned to predeclared character variable.

61) What is character constants?
A character constant is a single character, enclosed within the pair of single quotation mark (apostrophes).

62) What is string constants?
A string constant or literal contains a sequence of zero or more characters or escape seauences enclosed in double Quotation marks.

63) What is integer constants?
An integer constant is an integer-valued number. It can represent decimal, octal, or hexadecimal values.

64) What is floating point constants?
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

65) What is the difference between fread and fwrite function?
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.

66)What are the uses of a pointer?
Pointer is used in the following cases
It is used to access array elements
It is used for dynamic memory allocation
It is used in Call by reference
It is used in data structures like trees, graph, linked list etc.

67) What are linker error?
The Linker Errors occur during the linking process when the external symbols referred to by the program are not resolved.

68) What are runtime error?
The Runtime Errors occur while a program is being run and hence the name. They occur due to both program internal and external factors.
.
69) When do we get logical errors?
The Logical Errors occur if the solution procedure for the given problem itself is wrong.
In this case, the outputs produced by the programs would be incorrect.
Correcting the solution procedure itself by better understanding of the problem eliminates these errors.
The Logical Errors (if any) are to be figured out by ourselves by verifying the outputs that are produced by the program.

70) Do character constants represent numerical values?
Yes, each character constant associates an integer value with it.

71) What is the purpose of scanf() and printf() functions?
The function scanf() is used for formatted input from the standard input and provides many of the conversion facilities.
It is used for formatted output to standard output device, that is, screen. The format specification string and the data to be output, are the arguments (parameters) to the printf() function.

72) What is type qualifiers?
Type qualifier adds properties to an identifier. Type qualifiers describe the manner in which the object will be modified. The application of qualifiers to an object does not affect the range or the arithmetic properties of the object.

73) What are the types of type qualifiers in c?
The two type qualifiers provided by C are :
const
volatile

74) What is meant by inheritance?
Inheritance is the process by which objects of one class acquire properties of objects of another class..

75) Do string constants represent numerical values?
No, the string constants donot have a corresponding numerical value.

76) What is meant by operator precedence?
Operator precedence describes the order in which C evaluates different operators in a complex expression.

77) What is an Operator?
An operator is a symbol, which instructs the computer to perform the specified manipulation over some data. The rich set of operators available in C enable us to write efficient and concise programs and this fact serves to set C apart from any other programming languages.

78) What are the types of operators in c?
Assignment operator
Arithmetic operators
Relational operators
Logical operators
Increment/Decrement operators
Shorthand arithmetic assignment operators
Conditional operator
Bitwise operators
Sizeof() operator
Comma operator

79) What is a ternary operator in C?
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 :.

80) What is assignment operator?
An operator is a symbol that operates on a certain data type.In C, the ’=’ symbol is known as the assignment operator. It sots the value of the variable on the left hand side of it to that of the right hand side of it.

81) What are the types of assignment statements?
C supports a variety of assignment statements. These are given below :
Simple assignment statement
Multiple assignment statement
Arithmetic assignment statement

82) What is the sizeof () operator?
Even though it looks like a keyword, sizeof( ) is an operator which is used to know the memory size of the data types and variables. This operator returns the number of bytes allocated for the variable (or) data type. The format of the sizeof() operator is as follows.
sizeof (v);
where v is a variable name / data type / value.

83) What is the use of bitwise operator?
The bitwise operator performs the operation on bits (i.e. bit by bit). Using the bitwise operators we can set / reset / check any bit in the value of the variable.


84) What is the Difference between = and = = Operators?
The two operators = and == are used for assignment and checking respectively. If not properly used, it causes many problems. The following program illustrates what will happen if we use = instead of = =.

85) What is unary operator?
The operators that act upon a single operand to produce a new value are known as unary operators.

86) What are the types of unary operators?
C support unary operators are :
minus operator -
increment operator + +
decrement operator –
size operator
(type) operator

87) What is the difference between break and continue?
The break statement is used to exit from all the loop constructs (while, do while and for) and switch.case statements, whereas the continue statement is used to skip all subsequent instructions and can control back to the loop control. The continue statement can be used for any loop construct.

88)What is storage class?
The storage class in C provides the complete information about the location and visibility of variables. Scope of a variable means the portion of the program within which it can be referenced and lifetime means the time of its existence in the memory.

89) What are the different storage classes in C?
There are four types of storage classes.
Automatic : Variable used as a local variable. This is the default one. Initial value of variable is garbage value without initialization.
Extern : Variable used as a local variable. Retains its value during next function call.
Regiter : Variable used as a local variable. May be stored in register if possible. Default initial value is garbage value.
Static : Variable used as a global variable.

90) What are the types of bitwise operator?
There are three types of bitwise operator.
Bitwise AND(&)
Bitwise OR(|)
Bitwise Exclusive OR(^)

91) What is difference between function overloading and operator overloading?
A function is overloaded when same name is given to different function.While overloading a function, the return type of the functions need to be the same.

92) What is getche() function?
It returns a character just entered from the standard input unit. The entered character is echoed (displayed) to the computer screen. It reads a single character the moment it is typed without waiting for the Enter key to be hit.

93) What is getch() function?
It returns a character just entered from the standard input unit. The entered character is not echoed on the screen. It reads a single character the moment it is typed without waiting for the Enter key to be hit.

94) What is putchar() function?
It prints the character constant or the character variable to the standard output device. The function putchar( ) has the following form :
putchar (var name)

95) What is an arrays?
Arrays can be defined as a collection of variables of the same type that are referred through a common name.

96) What are the advantages of the functions?
It reduces the complexity in a program by reducing the code
Function are easily understanding and reliability and execution is faster
It also reduces the time to run a program.In other way, Its directly proportional to complexity
Its easy to find-out the errors due to the blocks made as function definition outside the main function.

97)What are the characteristics of arrays in C?
An array holds elements that have the same data type
Array elements are stored in subsequent memory locations
Two–dimensional array elements are stored row by row in subsequent memory locations
Array name represents the address of the starting element
Array size should be mentioned in the declaration. Array size must be a constant expression and not a variable.

98) What is the difference between arrays and pointers?
Array is collection of similar datatype. it is a static memory allocation means we can not increment and decrement the arry size once we allocated. and we can not increment the base address, reassign address.
Pointer is a dynamic memory allocation. we can allocate the size as we want, assigning into another variable and base address incrementation is allowed.

99) What is else if ladder?
The else if ladder helps select one out of many alternative blocks of statements for execution depending on the mutually exclusive conditions.

100) What is class?
A class represents description of objects that share same attributes and actions. It defines the characteristics of the objects such as attributes and actions or behaviors. It is the blue print that describes objects.

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