ADVANCED C PROGRAMMING UNIT I TWO MARKS

ADVANCED C PROGRAMMING

UNIT1: INTRODUCTION

	Describe the c language history in short.
	1.    C language is a structure oriented programming language, was developed at Bell Laboratories in 1972 by Dennis Ritchie 2.    C language features were derived from earlier language called “B” (Basic Combined Programming Language – BCPL) 3.    C language was invented for implementing UNIX operating system 4.    In 1978, Dennis Ritchie and Brian Kernighan published the first edition  “The C Programming Language” and commonly known as K&R C 5.    In 1983, the American National Standards Institute (ANSI) established a committee to provide a modern, comprehensive definition of C. The resulting definition, the ANSI standard, or “ANSI C”, was completed late 1988.
	Why C language is called middle-level language?
	It is not as difficult like assembly level language. It combines features of high level language and functionality of assembly language. It is well suited for writing both application software and system software.
	List the characteristic features of C language.
	1.    It is highly structured language. 2.    It uses the features of both high level language and assembly language. 3.    C is machine independent language and it is highly portable. 4.    It supports a variety of data types and a powerful set of operators. 5.    It supports dynamic memory management by using concept of pointers. 6.    It is the middle level language.
	What are the uses of C language?
	C language is used for developing system applications that forms major portion of operating systems such as Windows, UNIX and Linux. Below are some examples of C being used. 1.    Database systems 2.    Graphics packages 3.    Word processors 4.    Spread sheets 5.    Operating system development 6.    Compilers and Assemblers 7.    Network drivers 8.    Interpreters
	What are the C standards?
	1.    C89/C90 standard – First standardized specification for C language was developed by American National Standards Institute in 1989. C89 and C90 standards refer to the same programming language. 2.    C99 standard – Next revision was published in 1999 that introduced new futures like advanced data types and other changes.
	What is the basic structure of C program?
	Structure of C program is defined by set of rules called protocol, to be followed by programmer while writing C program. All C programs are having sections/parts which are mentioned  below. 1.    Documentation section 2.    Link Section 3.    Definition Section 4.    Global declaration section 5.    Function prototype declaration section 6.    Main function 7.    User defined function definition section
	Why header files are included in ‘C’ programming?
	This section is used to include the function definitions used in the program. Each header file has ‘h’ extension and include using ’# include’ directive at the beginning of a program.
	What are the rules for writing program in C?
	1.    All statements should be written in lower case letters. Uppercase only for symbolic constants. Eg. PI 2.    Blank spaces should be inserted between the words to improve readability. 3.    It is not necessary to fix the position of statement in the program. 4.    The opening and closing braces should be balanced.
	List out some of the rules used for ‘C’ programming.
	1.    All statements should be written in lower case letters. Upper case letters are only for symbolic constants. 2.    Blank spaces may be inserted between the words. This improves the readability of statements. 3.    It is a free-form language; we can write statements anywhere between ‘{‘ and ‘}’. a = b + c; d = b*c; (or) a = b+c; d = b*c; Opening and closing braces should be balanced.
	List the various sections of C program.
	1.    Include header file section 2.    Global Declaration Section 3.    Function main 4.    Declaration part 5.    Executable part 6.    User-defined functions
	Write the description for each section of a C program.
	S.No Sections Description 1 Documentation section We can give comments about the program, creation or modified date, author name etc in this section. The characters or words or anything which are given between “/*” and “*/”, won’t be considered by C compiler for compilation process.These will be ignored by C compiler during compilation. Example : /* comment line1 comment line2 comment 3 */ 2 Link Section Header files that are required to execute a C program are included in this section 3 Definition Section In this section, variables are defined and values are set to these variables. 4 Global declaration section Global variables are defined in this section. When a variable is to be used throughout the program, can be defined in this section. 5 Function prototype declaration section Function prototype gives many information about a function like return type, parameter names used inside the function. 6 Main function Every C program is started from main function and this function contains two major sections called declaration section and executable section. 7 User defined function section User can define their own functions in this section which perform particular task as per the user requirement.
	Write short notes about main ( ) function in ’C’ program.
	1.    Every C program must have main ( ) function. 2.    All functions in C, has to end with ‘( )’ parenthesis. 3.    It is a starting point of all ‘C’ programs. 4.    The program execution starts from the opening brace ‘{‘ and ends with closing brace 5.    ‘}’, within which executable part of the program exists.
	What do you mean by variables in ‘C’?
	1.    A variable is a data name used for storing a data value. 2.    Can be assigned different values at different times during program execution. 3.    Can be chosen by programmer in a meaningful way so as to reflect its function in the program. 4.    Some examples are: Sum percent_1 class_total
	Why we don’t use the symbol ‘&’ symbol, while reading a String through scanf()?
	The ‘&’ is not used in scanf() while reading string, because the character variable itself specifies as a base address. Example: name, &name[0] both the declarations are same.
	What are the c tokens?
	C tokens can be classified as follows: 1.     Keywords 2.     Identifiers 3.     Constants 4.     Strings 5.     Special Symbols 6.     Operators
	What is the difference between ‘a’ and “a”?
	‘a’ is a character constant and “a” is a string.
	What are the different data types available in advanced C?
	There are four data types in C language. They are, S.no Types Data Types 1 Basic data types int, char, float, double 2 Enumeration data type enum 3 Derived data type pointer, array, structure, union 4 Void data type void
	Define with example integer and floating type of data in C language.
	Integer data: 1.    Integers are whole numbers with a range of values supported by a particular machine. Integers occupy a one word of storage and word size varies from 16 to 32 bits. 2.    It is defined by a keyword called int. Short integer occupies 2 bytes of memory, Long integer occupies 4 bytes of memory, Signed integer occupies 2 bytes of memory, and unsigned integer occupies 2 bytes of memory. Example: int a, long int c=10. Floating data: 1.    Floating point or real numbers are stored in 32 bits with 6 digits precision. 2.    It is defined by a keyword called float. It occupies four bytes of memory. Example: float a.
	How many bytes are occupied by the int, char, float, long int and double?
	int - 2 Bytes char - 1 Byte float - 4 Bytes long int - 4 Bytes double - 8 Bytes
	What are the modifiers available in C language?
	There are 5 modifiers available in C language. They are, 1.    short 2.    long 3.    signed 4.    unsigned 5.    long long
	What is type casting?
	Type casting is the process of converting the value of an expression to a particular data type. Example: int x,y; c = (float) x/y; where a and y are defined as integers. Then the result of x/y is converted into float.
	Categorize the operators used in c.
	1.    Arithmetic operators 2.    Relational operators 3.    Logical operators 4.    Assignment operators 5.    Increment and decrement operators 6.    Conditional operators 7.    Bitwise operators 8.    Special operators
	What is an Operator and Operand?
	An operator is a symbol that specifies an operation to be performed on operands. Example: *, +, -, / are called arithmetic operators. The data items that operators act upon are called operands. Example: a+b; In this statement a and b are called operands.
	What is Ternary operators or Conditional operators?
	Ternary operators is a conditional operator with symbols ? and : Syntax: variable = exp1 ? exp2 : exp3 If the exp1 is true variable takes value of exp2. If the exp2 is false, variable takes the value of exp3.
	What is a Modulo Operator?
	‘%’ is modulo operator. It gives the remainder of an integer division Example: a=17, b=6. Then c=%b gives 5.
	What is Bit wise operation in C?
	Bitwise operators are special C operators that help to manipulate data at bit level. C supports various bitwise operators for performing bitwise operations. Some of the typical bitwise operations are 1.    Bitwise AND & 2.    Bitwise OR | 3.    Bitwise XOR ^ 4.    Shift Left << 5.    Shift Right >>
	What are the logical operators available in „C‟?
	The logical operators available in ‘C’ are 1.    Logical AND && 2.    Logical OR || 3.    Logical NOT !
	What is the difference between Logical AND and Bitwise AND?
	Logical AND (&&): Only used in conjunction with two expressions, to test more than one condition. If both the conditions are true the returns 1. If false then return 0. Bitwise AND (&): Only used in Bitwise manipulation. It is a unary operator.
	What is the difference between „=‟ and „==‟ operator?
	Where = is an assignment operator and == is a relational operator. Example: while (i=5) is an infinite loop because it is a non zero value and while (i==5) is true only when i=5.
	What is the use of sizeof( ) operator?
	The sizeof ( ) operator gives the bytes occupied by a variable. No of bytes occupied varies from variable to variable depending upon its data types. Example: int x,y; printf(“%d”,sizeof(x)); Output: 2
	Distinguish Increment and Decrement operators.
	S No Increment ++ Decrement -- 1 Adds one to its operand Subtracts one from its operand 2 Equivalent x = x + 1 Equivalent x = x - 1 3 Either follow or precede operand Either follow or precede operand 4 Example : ++x; x++; Example : --x; x--;
	What is the difference between ++a and a++?
	++a means do the increment before the operation (pre increment) a++ means do the increment after the operation (post increment) Example: a=5; x=a++; /* assign x=5*/ y=a; /*now y assigns y=6*/ x=++a; /*assigns x=7*/
	What is a loop control statement?
	Many tasks done with the help of a computer are repetitive in nature. Such tasks can be done with loop control statements.
	What is the difference between if and while statement?
	If statement: 1.    It is a conditional statement 2.    If the condition is true, it executes some statements. 3.    If the condition is false then it stops the execution the statements. While statement: 1.    It is a loop control statement 2.    Executes the statements within the while block if the condition is true. 3.    If the condition is false the control is transferred to the next statement of the loop.
	Differentiate between do-while and while-do (or) while loop.
	do-while while-do/while It is an exit controlled loop It is an entry controlled loop Body of the loop executed first and then the condition is checked. Condition is checked first and the body of the loop is executed. The body of the loop executed even once if the condition fails in the first evaluation. The body of the loop will not be executed if the condition fails in the first evaluation.
	What is the difference between while loop and do…while loop?
	In the while loop the condition is first executed. If the condition is true then it executes the body of the loop. When the condition is false it comes of the loop. In the do…while loop first the statement is executed and then the condition is checked. The do…while loop will execute at least one time even though the condition is false at the very first time.
	Give the syntax for the ‘for’ loop statement
	for (Initialize counter; Test condition; Increment / Decrement) { statements; } Initialization counter sets the loop to an initial value. This statement is executed only once. The test condition is a relational expression that determines the number of iterations desired or it determines when to exit from the loop. The ‘for’ loop continues to execute as long as conditional test is satisfied. When condition becomes false, the control of program exists the body of the ‘for’ loop and executes next statement after the body of the loop. The increment / decrement parameter decides how to make changes in the loop. The body of the loop may contain either a single statement or multiple statements.
	Compare switch( ) and nestedif statement.
	S No switch( ) case nested if 1 Test for equality ie., only constant values are applicable. It can equate relational (or)logical expressions. 2 No two case statements in same switch. Same conditions may be repeated for a number of times. 3 Character constants are automatically converted to integers. Character constants are automatically converted to integers. 4 In switch( ) case statement nested if can be used. In nested if statement switch case can be used.
	Differentiate break and continue statement
	S No break continue 1 Exits from current block / loop Loop takes next iteration 2 Control passes to next statement Control passes to beginning of loop 3 Terminates the program Never terminates the program
	Write rules for defining real constants.
	1.    It must have at least one digit. 2.    It must have a decimal point. 3.    It should not have blank spaces and comma inside. 4.    Negative values should be written by an explicit minus (-) sign. If no sign is mentioned by default it is assumed to be positive.
	Differentiate between signed and unsigned integer.
	Signed Integer Unsigned Integer It stores value along with the sign of the integer.(i.e.) it holds whether it is positive or negative It only stores the absolute value irrespective of the sign. In signed integer the most significant bit store the sign (+ or -) and the remaining seven bits stores the absolute value. In unsigned integer all the 8 bits store the absolute value. Ex: signed int a= -5,b = 4 Ex: unsigned int a = 5
	What are the Escape Sequences present in „C‟.
	1.    \n - New Line 2.    \b – Backspace 3.    \t - Form feed 4.    \\ - Backspace 5.    \t – Tab 6.    \r - Carriage return 7.    \” - Double quotes
	Write the limitations of getchar( ) and sacnf( ) functions for reading strings.
	getchar( ): To read a single character from stdio, then getchar() is the appropriate. scanf( ): scanf( ) allows to read more than just a single character at a time.
	What is a global variable?
	The global variable is a variable that is declared outside of all the functions. The global variable is stored in memory, the default value is zero. Scope of this variable is available in all the functions. Life as long as the program’s execution doesn’t come to an end.
	What are delimiters and what is the use?
	They are special symbols such as 1.    : Colon Used for label 2.    ; Semi colon Terminates statement 3.    () Parenthesis Used in expression and function 4.    [] Square Bracket Used for array declaration 5.    {} Curly Brace Scope of statement 6.    # Hash Preprocessor directive 7.    , Comma Variable Separator
	Write short notes about main ( ) function in “C” program.
	1.    Every C program must have main ( ) function. 2.    All functions in C, has to end with ‘( )’ parenthesis. 3.    It is a starting point of all ‘C’ programs. 4.    The program execution starts from the opening brace ‘{‘and ends with closing brace ‘}’, within which executable part of the program exists.
	What is the difference between auto and static storage class?
	Static Auto Storage Memory Memory Initial value zero Garbage value Scope Local to the block in which variable is declared. Local to the block in which variable is declared. Life Value of the variable persists between different function calls. Value of the variable persists inside the block in which the variable is defined.
	Write a program to swap the values of two variables (without temporary variable).
	#include <stdio.h> #include <conio.h> void main( ) { int a =5; b = 10; clrscr( ); prinf(“Before swapping a = %d b = %d “, a , b); a = a + b; B = a – b; a = a – b; prinf(“After swapping a = %d b = %d”, a,b); getch( ); } Output: Before swapping a = 5 b = 10 After swapping a = 10 b = 5
	What is the output of the following program when, the name given with spaces?
	main() { char name[50]; printf(“\n name\n”); scanf(“%s, name); printf(“%s”,name); } Output: SANTHOSH(It only accepts the data upto the spaces)
	What is the output of the programs given below?
	main() main() { { float a; float a; int x=6, y=4; int x=6, y=4; a=x\y; a=(float) x\y; printf(“Value of a=%f”, a); printf(“Value of a=%f”,a); } } Output: Output: 1. 1.500000
	What is a String?
	String is an array of characters. Construct an infinite loop using while? while (1) { } Here 1 is a non zero, value so the condition is always true. So it is an infinite loop.
	What is meant by Control String in Input/Output Statements?
	Control Statements contains the format code characters, specifies the type of data that the user accessed within the Input/Output statements.