Operators and expressions,control structures in C

7/31/2019 Operators and expressions,control structures in C

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Operators An operator is a symbol that specifies arithmetic , logical or

relational operation to be performed.

The data items that operators act upon are called operands.

An expression is any computation involving variables and operatorsthat yields a value.

operators

arithmetical assignment equality Relational Logical bitwise

unarybinary

ternary


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ARITHMETIC OPERATORS There are five arithmetic operators in C. They are

The% operator is also called as modulus operatorArithmetic operators are binary operators because they are operators act upon 2operands


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The operands acted upon by arithmetic operators

must represent numeric values

The remainder operator(%) requires that both

operands be integers and the second operand be

nonzero.

the division operator(/) requires that the second

operand be nonzero.


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Example a and b 2 integer variables with 14 and 4 as

values

a+b=18

a-b=10

a*b=56

a/b=3(decimal part truncated)

a%b=2(remainder of division)


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UNARY OPERATORS

operators that act upon a single operand to produce a new value arecalled unary operators.

Unary minus operator

Unary operator negates the value of its operand

This operator reverses sign of the operand value

If a=5 thena will be -5

If a=-4 thena will be 4

-a doesnot change the value of a at the location where it permanently

resides in memory


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unary increment and decrement operator(++,--)

Unary ++ and operators increment or decrement value of a variable by 1

These operators taking 2 forms

Prefix

++var first add 1 to the variable var . then the result is assigned to thevariable on the left.

--var first subtract 1 from the variable var . then the result is assigned to the

variable on the left.

Postfix-first assigns the value to the variable on left and then

increments/decrements value of the variable.


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Example

Let int i=1printf("i = %d\n", i);printf (i= %d\n", ++i);printf("i = %d\n", i);

output will be i=1i=2i=2

printf ("i = %d\n" i);printf("i = %d\n", i++);

printf("i = %d\n", i);

output will bei=1i=1

i=2


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Basic rules for using ++ and --

operators The operand must be a variable but not a constant or

an expression

The operator ++ and may precede or succeed theoperand


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Sizeof operatorsizeof is a unary compile time operator that returns the number of

bytes the operand occupies.

General format

Sizeof var (where var is a declared variable)

Or

Sizeof(type) (where type is a c data type)

Example

Int a;

Printf(size of variable a=%d,sizeof a);Will print size of variable a=2;


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RELATIONAL OPERATORS

Relational operators are used for comparing numerical quantities.

Relational operators evaluate to 1,representing true outcome or 0

representing the false

Expression containing relational operators is called relational expression


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The operands of a relational operator must evaluate to a number.

Characters are valid operands since they are represented by numeric

values. For ex

A < F /*will give the output 1 because comparing ascii values of A

and F

Relational operators should not be used for comparing strings this

will results in string addresses being compared , not string contents

For example HELLO< BYE cause the address of HELLO to be

compared to the address of BYE.

For example int i=2,j=3i


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Logical operators

Logical operators&& and || are used to combine two or more

relational expressions.An expression which combines 2 or more relational expressionis termed as logical expressionLogical And produces 0 if one or both operands evaluate to0.otherwise produces 1

Logical OR produce 0 if both operands evaluate to 0 otherwiseit roduce 1


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Logical not( ! ) is a unary operator negates the logical value of its singleoperand .it causes an expression that is originally true to become false, andvice versa.


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Examples of logical expression

i=4,j=3

(i>j)||(i==j) this will return 1

(i>j)&&(i==j) will return 0

!(i>j) will return 0;


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Assignment operatorsassign the value of an expression to an identifier

assignment operators are used to form assignment expressions

Assignment expressions are written in the form

identifier = expression

identifier generally represents a variable.

Expression represents a constant, a variable or a more complex

expression.


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Examples of assignment expressions

a=3

sum = a + b

assignment operator = and the equality operator == are distinct.assignment operator is used to assign a value to an identifier,whereas the equality operator is used to determine if twoexpressions have the same value


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Multiple assignments of the form

identifier 1 = identifier 2 = .... = expression

is permissible in C

In such situations, the assignments are carried out from right to leftidentifier 1 = identifier 2 = expression

is equivalent to

identifier 1 = (identifier 2 = expression)

Examplei=j=5 here 5 is first assigned to j.then value of j assigned

to i


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Beside = operator, C programming language supportsother short hand format which acts the same assignmentoperator with arithmetic operators a+=b means a=a+b


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Conditional(ternary) operator

C offers a conditional operator(?: that store a value depending on a

condition.

A conditional expression is written in the form

expression 1 ?expression 2 : expression 3

When evaluating a conditional expression, expression Iis evaluated

first. Ifexpression 1 is truethen expression 2is evaluated and this

becomes the value of the conditionalexpression.

if expression 1 is false, thenexpression 3is evaluatedand this

becomes the value of the conditional expression.

For example z = (a > b) ? a : b;


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Comma operator

The comma operator can be used to link related expressions together.

A comma-linked list of expressions are evaluated left to right and value

of right most expression is accepted as final result

The general form of an expression using comma operator is

Expression M=(expression1,expression2,..............expressionN);

Since comma has the lowest precedence in operators the parenthesis is

necessary.


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Examples of comma operatorint m=1;

int n;

n = (m=m+3 , m%3);Here m =m+3 evaluated first and will assign 4,then m%3

evaluated and the result 1 is assigned to n

P d d i ti it f f


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Precedence and associativity of of

operators Precedence is used to determine the order in which different

operators in a complex expression are evaluated.

Associativity is used to determine the order in which operatorswith the same precedence are evaluated in a complexexpression.

Highest priority is for () and lowest for comma.Postfix ++ and - -has higher priority than prefix ++ and - -Unary operators has higher priority than binary operatorsRelational operators having precedence less than arithmetic

and unary operatorsLogical AND has higher precedence than logical OR

Operator Associati it


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Operator Associativity

()[].

->++ --(postfix)

left-to-right

++ --(prefix)+ -! ~

sizeof(type)*(indirection)&(address)

right-to-left

* / % left-to-right

+ - left-to-right


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=+= -=

*= /=%= &=^= |=

=

right-to-left

, left-to-right

> left-to-right

< >=

left-to-right

== != left-to-right

& left-to-right

^ left-to-right| left-to-right

&& left-to-right

|| left-to-right

?: right-to-left


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Type conversion

Type conversion occurs when the expression has data of mixed data types.

example of such expression include converting an integer value in to a float value,

or assigning the value of the expression to a variable with different data type.

In type conversion, the data type is promoted from lower to higher because

converting higher to lower involves loss of precision and value.


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Implicit conversion

It is the automatic conversion done by compiler withoutprogrammers intervention

Rules for implicit conversion1. If either operand is long double, convert the other to long

double.2. Otherwise, if either operand is double, convert the other

to double.3. Otherwise, if either operand is float, convert the other tofloat.

4. Otherwise, convert char and short to int.5. Then, if either operand is long, convert the other to long.


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I integer variable with value 7

F f loat variable with 5.5

C char variable with value w I+F will have value 12.5

I+C will have value 126


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Explicit conversion Explicit conversion is user defined that forces an expression to be of

specific type

Explicit conversion of an operand to a specific type is calledtypecasting

General form of casting is

(data type) expression

The expression is converted to the data type specified inparenthesis

The data type associated with the expression itself is not changed bya cast. Rather, it is the value of theexpression that undergoes typeconversion


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For example i is an integer variable whose value is 7, and

f is a floating-point variable whose value is 8.5.

((int) (i + f)) % 4

For ex int a=100,b=40

float c;

c=a/b will result 2.000000 but actual value required is 2.5 for that

we have to use c=(float)a/b


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The C language is accompanied by a number of library functions

that carry out various commonly usedoperations or calculations

Library functions that are functionally similar are usually grouped

together as (compiled) object programs in separate library files. These

library files are supplied as a part of each C compiler.

A library function is accessed simply by writing the function name,

followed by a list of arguments thatrepresent information being

passed to the function. The arguments must be enclosed inparentheses and separated by commas.

Library functions


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In order to use a library function it may be necessary to include certain

specific information within the main portion of the program.

This information is generally stored in special files which are supplied

with the compiler. Thus, the required information can be obtained

simply by accessing these special files. This is accomplished with the

preprocessor statement #include; i.e.,

#include

where filename represents the name of a special file.

For example #include contains library functions for

mathematical operations


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Library functions for string

operations

strcat(s,t) Concatenate t to end of s

strcmp(s,t) return negative, zero, or positive fors t

strcpy(s,t) Copy t to s

strlen(s) return length of s

These library functions defined instring.h


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Mathematical Functions

sin(x) sine of x, x in radians

cos(x) cosine ofx, x in radiansexp(x) exponential function ex

log(x) natural logarithm of x

sqrt(x) square root ofx (x>0)

abs(i) absolute value of integer

variable

pow(x,y) xy

These functions defined in math.h


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Character Class Testing and Conversion

isalpha(c) non-zero if c is alphabetic, 0 if not

isupper(c) non-zero if c is upper case, 0 if notislower(c) non-zero if c is lower case, 0 if not

isdigit(c) non-zero if c is digit, 0 if not

isalnum(c) non-zero if isalpha(c) or isdigit(c), 0 if not

toupper(c) Return c converted to upper case

tolower(c) Return c converted to lower case


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Data input and output


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Console i/o functions The screen and keyboard together are called a console.

Console i/o functions classified to two categories

FormattedUnformatted


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Formatted functions

Type Input Output

char Scanf() Printf()

int Scanf() Printf()

float Scanf() Printf()

string Scanf() Printf()

unformatted functions

Type Input Output

char Getch()Getche()Getchar()

Putch()Putchar()

int

float

string Gets() Puts()

Console input/output fuctions


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getch() and getche()Getch() function will read a single character the instant it is typed by

programmer without waiting for the Enter Key to be hit. The typed

character is not echoed on screen.

Getche() function will also read a single character the instant it is

typed by programmer without waiting for the Enter key to be hit, just like

getch() function. Getche() echoes the character on screen that you

typed.


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#include

#include

Void Main()

{char ch;

printf(Press any key to continue");

getch(); //will not echo the character

printf(Type any character:");

ch=getche();

}


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putch() putch() writes a character to the screen.

#include

Void Main()

{

Char ch=A;

Putch(ch);

}

ng e c aracter nput getc ar


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ng e c aracter nput

getc arfunction

Getchar() is an input function that reads a single character from

standard input device.

The getchar function is a part of the standard C I/O library.

This function does not require any arguments , but still have to use

empty parenthesis.

The getchar has the following form.

Char_variable = getchar();

Char_variable must be previously declared character variable.


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On end of file the value of EOF is returned.

Usually EOF will be assigned the value -1, though this may vary fromone compiler to another.

#include

main()

{

char C;

printf("Type one character:");

C=getchar();

printf(" The character you typed is = %c",C);


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SINGLE CHARACTER OUTPUT -putchar FUNCTION

Single characters can be displayed using the C libraryfunction putchar.

It transmits a single character to a standard outputdevice

The general form is

putchar (char_variable );

Char_variable must be previously declared character variable


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#include

main()

{char in;

printf(" enter one character ");

in=getchar();

Printf(entered character is );

putchar(in);

}


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Formatted input and output

functionsWhen input and output is required in specified format

the standard library functions scanf and printf areused.

scan


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scanScanf() allows to enter data from the keyboard that will be formatted

in a certain way.

The function returns the number of data items that have been entered

successfully.

General form of scanf

scanf(control string,arg1,arg2.......argn);

Control string is a string that can consist of format specifiers.it

indicates the format and type of data to be read from standard input

device.

Argl,arg2, . . . argn are arguments that represent the individual input

data items.

These arguments are preceded with the address-of operator to

indicate the address of data item in memory


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There is no need to use & for strings stored in arraysbecause array name is already a pointer

F ifi i f()


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Conversion

CharacterDatatype

d Signed decimal integer

i decimal, hexadecimal oroctal integer

o octal integer

u unsigned decimal integerx hexadecimal integer

c single character

s string

e Float or doublef Float or double

g Float or double

%lf double

Format specifiers in scanf()


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the size qualifier conversion characters may be preceded with certainconversion characters

main( )


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{

char item[20];

i n t partno;

f l o a t cost;

. . . . .

scanf("%s %d %f",item, &partno, &cost);

. . . . .

}

%s, indicates that the first argument (item) represents a string.

%d, indicates that the second argument (&partno) represents a decimal

integer value

%f,indicates that the third argument (&cost) represents a floating-point

value

More on scanf


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While Inputting Integer numbers we can also specify the field width of a

number.general format is

%wd

w integer specifies the field width of the number to be read

d - integer

Examples

Scanf(%2d %5d,&num1,&num2);Data inputted 25 12345 then 25 assigned to num1 and 12345 to num2

Suppose data inputted is 12345 25 then 12 will be assigned to num1 and

345 to num2

Inputting integer numbers

More on scanfThe format specifier %% is used for single % character in the inputstream.

We can use following conversion specifications for strings


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We can use following conversion specifications for strings

%[characters]

%[^characters]

The specification %[characters]means that only the character

specified with in the brackets are permissible in the input string.if input

string contains any other character string will be terminated at the first

encounter of such character.

With the help of %[] scanf can be used to read string with blank

spaces.

The specification %[^characters] means the characters specified

after the circumflex(^) are not permitted in the input string. The reading

of string will be terminated at the encounter of one of these character

Example of %[]


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Example of %[]

main()

{ char address[80];printf("Enter address\n");scanf("%[a-z]", address);printf(%-80s,address);

}OutputEnter addressnew york 122345

new york

Example of %[^]


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Example of %[ ]

main(){

char address[80];

printf("Enter address\n");scanf("%[^\n]", address);printf("%-80s", address);

}

OutputEnter addressNew Delhi 110 002New Delhi 110 002


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Scanf will stop reading a value of a variable infollowing cases

A white space character found in numericspecification

Maximum number of characters have been read

An error detected

The end of file is reached


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Printf() O/P data can be written from the computer onto a standard O/Pdevice using the library function printf

General form is

printf(control string,arg1,arg2.....argn);

where control string refers to a string that contains formattinginformation, and arg1, arg2, . . . , argn are arguments that representthe individual output data items.

Control string contain 3 types of items

characters that are simply printed as they are conversion specification that begin with a % sign

escape sequence that begin with a \sign

Format specifiers for printf()


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Format specifiers for printf()

Conversion

CharacterDatatype

d Signed decimal integer

i decimal, hexadecimal oroctal integer

o octal integer

u unsigned decimal integerx hexadecimal integer

c single character

s string

e Float or double

f Float or double

g Float or double

%lf double

the size qualifier

conversion characters maybe preceded with certainconversion characters.size qualifier charactersare h for short,l for longand L for long double

More on printf()


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More on printf()Outputting integer numbers While outputting a integer number we can also specify minimum field

width for the output. General format is

%wd

w-minimum field width for output.

if number grater than specified field width it will be printed in full

overriding minimum specificationd-value to be printed is a integer

The number is written right justified in the given field width

Examples


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Examples

Format output

Printf(%d,1234);

Printf(%6d,1234);

1 2 3 4

1 2 3 4

1 2 3 4

Printf(%-6d,1234)

Printf(%2d,1234);

1 2 3 4

Outputting real numbers


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For outputting real numbers we can specify number of digits after

decimal point and minimum number of positions that are to be used for

display

General format is

%w.pf

w-minimum field width specification

p- specifies no.of digits to be displayed after decimal point(precision)

We can also use

printf(%*.*f,width,precision,number); here width and precision

supplied at runtime. For example printf(*.*f,7,2,number); is equivalent

to printf(%7.2f,number);

examples


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examples

To print Float

y=98.7654Format

Printf(%7.4f,y)

Printf(%7.2f,y)

Printf(%-7.2f,y)

Printf( %f,y)

Printf(%10.2e,y)

9 8 . 7 6 5 4

9 8 . 7 7

9 8 . 7 6 5 4

9 . 8 8 e + 0 1

output

9 8 . 7 7


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Outputting stringsA single character can be displayed in desired position

using %wc

The character will be displayed right justified in field

of w columns

Format specification for outputting string is %w.ps

wherew specifies the field width for display and p

specifies only first p characters of the string are to bedisplayed


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examplesFor outputting strings NEW DELHI 110001specification output

%s

%20s

%20.10s

%5s%.5s

N E W D E L H I 1 1 0 0 0 1

N E W D E L H I 1 1 0 0 0 1

N E W D E L H I

N E W D E L H I 1 1 0 0 0 1

N E W D

N E D E L H I%-20.10s


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flag meaning

- left justifies the field; default is right justification.

+ always prefixes a signed value with a sign (+ or -).

0 pads numeric values with leading zeros. If both 0 and -appear as flags, the 0 flag is ignored.

# prefixes octal values with 0 and hexadecimal valueswith 0x or 0X.For floating point values, this forces the decimal point to bedisplayed, even if no characters follow it.

We can also include flags , which affects the appearance ofthe output in printfFlags are used immediately after % sign

Commonly used flags and their meaning given below


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Printf(%07.2f,y)

Printf(%-+6.1f,5.5)

0 0 9 8 . 7 7

+ 5 . 5

String input and output:gets and puts


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g p p g p

The gets function receives the string from standard input device.

A string is an array or set of characters. string may include whitespace

characters.

The standard form of the gets function is

gets (str)

Here str is a string variable

It will reads characters into str from keyboard until newline character is

encountered and will append a null character to the string


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puts outputs the string to the standard output device.

The standard form for the puts function is

puts (str)

where str is a string variable.

The puts function displays the contents stored in its

parameter on the screen.

In puts() function,we cannot pass more than one

argument.So it can display one string at a time.


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#include

Void main()

{

char s[80];

printf("Type a string less than 80 characters:");

gets(s);

Puts( The string types is: );

puts(s);

}


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Control statements C language provides statements that can alter the

flow of a sequence of instructions. Thesestatements are called control statements.

These statements help to jump from one part ofthe program to another.

The statements which specify the order of executionof statements are called control statements


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if

Program control statements

Conditionaltype

Selection/branching

Unconditional type

If-else

If-else-if

switchbreak goto continue

Iteration/looping

for while Do-while


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Control statements in broadly divided to two

Branching

Looping

Branching is deciding what actions to take and loopingis deciding how many times to take a certain action.

If statement


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If statement

The simplest form of the control statement is the If statement.

It is very frequently used in decision making and allowing the flow

of program execution.

Syntax

if (Test expression)

statement;

The test expression inside if should not end with a semicolon

If test expression evaluates to true, corresponding statement is

executed. If test expression evaluates to false control goes to next

executable statement.

The statement can be either simple or compound.


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Sample program for if construct

#includemain()

{

int number;

printf("Type a number:");

scanf("%d",&number);

if (number < 0)

number = -number;printf("The absolute value is %d \n", number);


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Type a number:11The absolute value is 11

Type a number:-5The absolute value is 5

If-else


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If...else is an extension of simple if statement.

General form is

if(test expression)

Statement1

Else

Statement 2

if the test expression evaluates to true, then program statement 1 isexecuted, otherwise program statement 2 will be executed.


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Flowchart of if else construct


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#include

void main()

{

int a,b;

printf("Enter 2 number");

scanf("%d%d",&a,&b);if (a>b)

printf("%d is greater",a);

else

printf("%d is greater",b);}

Nesting of if..else statements


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gWhen series of decisions are involved we may have to

use more than if else statement in nested form.

A nested ifis a statement that has another ifin itsbody or in it else's body.

Nested if else having 3 formats

if(test expression 1){

if(testexpression 2)statement 1;

[else

statement 2;]

}else

body of else;


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if(test expression 1)

body-of-if;else

{

if(testexpression 2)

statement 1;

[else

statement 2;]

}

II

if(test expression 1 )III


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if(test expression 1 ){

if(test expression 2)statement 1 ;

[elsestatement 2;]

}

else{

if(test expression 3)statement3;

[elsestatement4;]

}


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/*sample code using nested if else */


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/*sample code using nested if-else */if(a>b)

{if(a>c)printf("%d is larger",a);

}else if(b>c)printf("%d is larger",b);else

printf("%d is larger",c);}

If-else-if ladder When a series of many conditions have to be checked


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When a series of many conditions have to be checkedwe may use the ladder else if statement

General form of ifelse-if ladder is

if (test Expression 1) statement 1;else if (test Expression 2)

statement2;else if (test Expression 3)

statement3;.

.

else if (Test Expression n)

statement n;else

statement-F;


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If expression1 is evaluated to true then statement 1 is executed.if expression2 is true then statement 2 is executed and so on. If none of

the test expression are true then statement F will be executed


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Sample code for ifelse- if ladder{


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{

----------

If(score>=80)

Grade=A;

Else if(score>=70 && score=60 && score=50 && score


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Looping allows set of instructions to be performed repeatedly until a

certain condition is fulfilled

There are 2 types of loops

Pre-test loop or entry controlled loop

Post-test loop or exit controlled loop

In entry controlled loop test expression is evaluated before entering

the loop.

In a exit controlled loop test expression is evaluated before exitingfrom the loop


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Testexpression

Body of loop

True

false

Pre-test loop

Body of loop

Testexpression

True

false

Post-test loop

In pretest loop ,loop body may not be executed where as in post-testloop loop body will be executed at least once


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C having 3 looping statements

For

WhileDo while

for and while are pretest/entry controlled loopsand do while is exit controlled/post test loops

Parts of loop


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Initialization expression(s)

before entering the loop, loop control variables must be initialized.

this initialization of control variable take place under initialization

expression .

This part of loop is the first to be executed.

Initialization expression(s) are executed only once in the beginning of theloop

Test expression

Test expression is an expression whose truth value decides whether the

loop-body will be executed or not .

If test expression evaluates to true loop body gets executed,otherwise loop

is terminated


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Update expression(s)

change value of loop control variable(s)

Update expression are executed every time through the loop before

test expression is tested

Body- of- theloop

The statements that are executed repeatedly form the body of the loop

While Loop


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pThe while statement is used to carry out looping operations, in which a

group of statements is executed repeatedly, until some condition hasbeen satisfied.

Is an entry controlled loop

The general form of the while statement is

while ( test expression)

statement

The statement will be executed repeatedly, as long as the expression

is true

Statements can be simple or compound,

start


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Initialization

Testexpression

Statement(s)

Update

expressions

True

false

Flowchart of while loop

In while loop,initialization of loop

control variable donebefore the loop starts.Updating mustincluded in the body of

the loop


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Sample program//to print numbers 1 to 10 using while loop

void main()

{

int i=1;while(i


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For loopIt is a commonly used loop

This loop is definite loop because programmer knows exactly how

many times loop will be executed

General format is

For(initialization; test expression; update expression)

statement;

Statements can be simple or compound, which is the body of loop

Fl h f f l


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Initialization

Testexpression

statementsUpdateexpressions

True

false

Flowchart of for loop

All the four parts of while loop is also present in for loop. but all are comprised inone line


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for loop can written as equivalent to while loop and vice versa

For(initialization; test expression; update expression)

statement;

Is equivalent to while

Initialization;

while ( test expression)

{

statement ;

Update expressions;

}


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Sample program using for loopvoid main()

{

int i;

For(i=1;i


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First feature is Multiple initialization and update expressions

For loop may contain multiple initialization and/or update expressions

Multiple expressions are separated by commas For(i=1,sum=0;i


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Do while loop It is a post-test loop

Test expression is evaluated after executed loop body at least once

General syntax is

do

{

statement

}

while (expression);

Statements will be executed until expression become false.


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Initialization

Testexpression

statements

Updateexpressions

True

false


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//to print numbers 1 to 10 using do-while loopvoid main(){

int i=1;do{printf("%d\n",i);

i++;}while(i


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p

Each loops having its own control variable or index

Inner loop must terminate before outer loop

for(i=1;i


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Nesting of whileint n,i=1,j=1;while(i


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Int i=1,j=1;

do

{

j=1;

do

{printf("%d",j);

j++;

}while(j


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The usage of multiple If else statement increases the complexity of

the program since when the number of If else statements increase it

affects the readability of the program and makes it difficult to follow the

program.

The switch statement removes these disadvantages by using asimple and straight forward approach.

c has a built-in multiway decision statement known as a switch

statement


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General format of switch statement is

Switch(expression)

{

Case constant 1:statementlist1;

break;

Case constant 2:statementlist2;

break;

..

Default :statementlist n}

Expression is an integer or character expression. When the switch statement

is executed the expression is evaluated first and the value is compared with the


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case label values in the given order.

If the case label matches with the value of the expression then the control is

transferred directly to the group of statements which follow the label.

If none of the statements matches then the statement against the default is

executed.

The default statement is optional in switch statement in case if any default

statement is not given and if none of the condition matches then no action takes

place in this case the control transfers to the next statement


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Break statement at the end of each statement block indicates end of

particular case and causes an exit from switch statement.

Even if there are multiple statements to be executed in each casethere is no need to enclose them within a pair of braces


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Sample codeswitch(choice)


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switch(choice)

{

case 1: printf(you entered menu choice #1);break;

case 2:printf(you entered menu choice #2);

break;

default:printf("Invalid Choice");break;

}

Once the statement list under a case is executed ,the flow of controlcontinues down executing all the following cases until the break is


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continues down executing all the following cases until the break isreached

Switch(number){Case 1:Case 3:Case 5:

Case 7:case 9 : printf(%d is an odd number,number);

break;Case 2:Case 4:

Case 6:Case 8:printf(%d is an even number,number);

break;Default:printf(%d is not between or including 1 and 9,number);

break;}


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Switch versus if-else Ladder


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1.Switch can only test for equality where if can evaluate a relational or

logical expression

2.switch cannot handle floating point test. Where if can handle floating

point test also apart from integer and character test

3.Switch statement select its branches by testing value of a same

variable against set of constants whereas if else use series of

expression that involve unrelated variables and complex expression

4.Switch case label value must be a constant

if 2 or more variables are to be compared use if-else


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breakThe break statement is used to terminate loops or to exit from a switch. It

can be used within a for, while,do -while, or switch statement.

The break statement is written simply as

break;

After a break is executed with in a loop or a case in switch execution

proceeds to the statement that follows loop or switch

When loops are nested break would only exit from the loop containing

it.i.e break will exit only a single loop


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While(){

.If(condition)break;

}

For(.){

if(condition)Break;....}

..

Exitfromloop

Exitfromloop

Do{

.If(condition)Break;.}While(..);

For(.){for(.)

{if(condition)

Break;.}..

}

Exitfromloop

Exitfromloop

Void main()

{


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{

int c=1;

While(c


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Break in nested loop

for(i=2;i


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continueContinue statement does not terminate the loop .it forces the next

iteration of the loop to take place, skipping any code in between.

On execution of continue statement control will goes to test

expression in while and do while statement and goes to the updating

expression in a for statement

While (test expr){

Continue;. . }}


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do{

.continue;

}while(testexpr);

For(initialization;testexpr;updation){

Continue;..}

void main(){


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{.

for(i=1;i


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continue

break continue

It helps to make an earlier exitfrom the block where it appears It helps in avoiding the remainingstatements in current iteration ofthe loop and continuing with thenext iteration

It can be used in all control

statements including switchconstruct

It can be used only in loop

constructs

GOTO statement:


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The goto statement is used to alter the normal sequence of program

execution by transferring control to some other part of the program.

In its general form, the goto statement is written as

goto label;

where label is an identifier that is used to label the target statementto which control will be transferred.


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Sample codevoid main()

{

float x,y;

read:

scanf(%f,&x);

if(x


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void main(){

int n,i;long int fact=1;scanf(%d,&n);if(n

Operators and expressions,control structures in C

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