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C Operators Notes

The Int Types

An int was originally intended to be the "natural" word size of the processor. Many

modern processors can handle different word sizes with equal ease.

It is int which causes the greatest confusion. Some people are certain that an int has 16bits and sizeof(int) is 2. Others are equally sure that an int has 32 bits and sizeof(int) is 4.

Who is right? On any given compiler, one or the other could be right. On some

compilers, both would be wrong. I know of one compiler for a 24 bit DSP where an inthas 24 bits.

The actual range of values which the signed and unsigned int types can hold are:

A signed int can hold all the values between INT_MIN and INT_MAX inclusive.

INT_MIN is required to be -32767 or less, INT_MAX must be at least 32767. Again,

many 2's complement implementations will define INT_MIN to be -32768 but this isnot required.

An unsigned int can hold all the values between 0 and UINT_MAX inclusive.

UINT_MAX must be at least 65535. The int types must contain at least 16 bits to holdthe required range of values.

NOTE:The required ranges for signed and unsigned int are identical to those for signed and unsignedshort. On compilers for 8 and 16 bit processors (including Intel x86 processors executing in 16 bit mode,

such as under MS-DOS), an int is usually 16 bits and has exactly the same representation as a short. On

compilers for 32 bit and larger processors (including Intel x86 processors executing in 32 bit mode, such as

Win32 or Linux) an int is usually 32 bits long and has exactly the same representation as a long.

The Short Int Types

There are two types of short int, signed and unsigned. If neither is specified the short is

signed. The "int" in the declaration is optional. All 6 of the following declarations arecorrect:

short x; x is a signed short int

short int x; x is a signed short int

signed short x; x is a signed short int

signed short int x; x is a signed short int

unsigned short x; x is an unsigned short int

unsigned short int x; x is an unsigned short int

The range of the short int types:

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C Operators Notes

A signed short can hold all the values between SHRT_MIN and SHRT_MAX inclusive.

SHRT_MIN is required to be -32767 or less, SHRT_MAX must be at least 32767.

Again, many 2's complement implementations will define SHRT_MIN to be -32768 butthis is not required.

An unsigned short can hold all the values between 0 and USHRT_MAX inclusive.USHRT_MAX must be at least 65535.

The short types must contain at least 16 bits to hold the required range of values.

On many (but not all) C implementations, a short is smaller than an int. Programs whichneed to have very large arrays of integer values in memory, or store very large numbers

of integers in files might save memory or storage space by using short in place of int if

both of the conditions below are met:1. Short is truly smaller than int on the implementation.

2. All of the required values can fit into a short.

NOTE: On some processor architectures code to manipulate shorts can be larger and

slower than corresponding code which deals with ints. This is particularly true on theIntel x86 processors executing 32 bit code, as in programs for Windows (NT/95/98),

Linux, and other UNIX derivatives. Every instruction which references a short in such

code is one byte larger and usually takes extra processor time to execute.

The Long Int Types

There are two types of long int, signed and unsigned. If neither is specified the long is

signed. The "int" in the declaration is optional. All 6 of the following declarations arecorrect:

long x; x is a signed long int

long int x; x is a signed long int

signed long x; x is a signed long int

signed long int x; x is a signed long int

unsigned long x; x is an unsigned long int

unsigned long int x; x is an unsigned long int

The range of the long int types:

A signed long can hold all the values between LONG_MIN and LONG_MAXinclusive. LONG_MIN is required to be -2147483647 or less, LONG_MAX must be at

least 2147483647. Again, many 2's complement implementations will define

LONG_MIN to be -2147483648 but this is not required.

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C Operators Notes

An unsigned long can hold all the values between 0 and ULONG_MAX inclusive.

ULONG_MAX must be at least 4294967295. The long types must contain at least 32

bits to hold the required range of values.

The Long Long Int Types (C Only)

64 bit processors have been readily available in workstations for several years, and they

will be coming to desktop computers soon. These processors can address enough memory

to have arrays with more elements than a 32 bit long can specify. Inexpensive disk drivesin use today can hold a file which contains more bytes than a 32 bit offset can reach. The

requirement for an integer type required to hold more than 32 bits is obvious.

The 1999 update to the ANSI/ISO C language standard has added a new integer type toC, one that is required to be at contain at least 64 bits.

Included in this update are the new variable types signed and unsigned long long . The

selected name comes from gcc and several other compilers which already provide thistype as an extension. On 32 bit Windows compilers from Microsoft, Borland (and maybeothers) this same extension has the name __int64.

While the C++ standard is quite new and most likely will not change for several years, it

is almost certain that C++ compilers will add support for these types as well. The C++

compilers which come with the implementations mentioned above do.

There are two types of long long int, signed and unsigned. If neither is specified the longlong is signed. The "int" in the declaration is optional. All 6 of the following declarations

are correct:

long long x; x is a signed long long int

long long int x; x is a signed long long int

signed long long x; x is a signed long long int

signed long long int x; x is a signed long long int

unsigned long long x; x is an unsigned long long int

unsigned long long int x; x is an unsigned long long int

The range of the long long int types:

A signed long long can hold all the values between LLONG_MIN and LLONG_MAXinclusive. LLONG_MIN is required to be -9223372036854775807 or less,

LLONG_MAX must be at least 9223372036854775807. Again, many 2's complementimplementations will define LLONG_MIN to be -9223372036854775808 but this is not

required.

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C Operators Notes

An unsigned long long can hold all the values between 0 and ULLONG_MAX inclusive.

ULLONG_MAX must be at least 18446744073709551615. The long types must contain

at least 64 bits to hold the required range of values.

Values In

The standard header contains macros which expand to values which allow a

program to determine information about the ranges of values each integer type can hold

at run time. Each of these types (except for "plain" char, that is char without a signed orunsigned in front of it) must be able to contain a minimum range of values.

Type Constant Minimum Value

signed charSCHAR_MIN

SCHAR_MAX

-127

127

unsigned charUCHAR_MAX

0255

"plain" charCHAR_MIN

CHAR_MAX(note 1)

signed shortSHRT_MIN

SHRT_MAX

-32767

32767

unsigned short

USHRT_MAX

0

65535

signed intINT_MIN

INT_MAX

-32767

32767

unsigned intUINT_MAX

065535

signed longLONG_MIN

LONG_MAX

-2147483647

2147483647

unsigned long

ULONG_MAX

0

4294967295

signed long longLLONG_MINLLONG_MAX

-92233720368547758079223372036854775807

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C Operators Notes

unsigned long longULLONG_MAX

018446744073709551615

Note 1: On implementations where default " plain" is signed, CHAR_MIN is equal to

SCHAR_MIN and CHAR_MAX is equal to SCHAR_MAX. If "plain" char is unsigned,CHAR_MIN is 0 and CHAR_MAX is equal to UCHAR_MAX.

OPERATORS:

C includes a large number of operators which fall into different categories. These are

Arithmetic Operators

Relational Operators

Logical Operators

Assignment Operators

Unary Operators

Conditional Operators

Bit-Wise Operators

Arithmetic Operators:

To solve most programming problems we need to perform arithmetic operations by

writing arithmetic expressions. The following table shows all arithmetic operatorsprovided by C.

Arithmetic

Operators

Meaning Declarations: int a=5, b=16

Double c=3.0, d=7.5Integer Examples Floating Point

Examples

+ Addition a + b is 21 c + d is 10.5

_ Subtraction a b is -11

b a is 11

c - d is -4.5

d c is 4.5

* Multiplication b * a is 80 c * d is 22.5

/ Division a / b is 5b / a is 3 c / d is 0.4d / c is 2.5

% Remainder

(ModuloDivision)

a % b is 5

b % a is 1 Not Possible

Each operator manipulates two operands, which may be constants, variables, or other

arithmetic expression. The arithmetic operators may be used with int or double data type

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operands. On the other hand, the remainder operator also known as modulus operator can

be used with integer operands to find the remainder of the division.

When both operands in an arithmetic expression are integers, the expression is

called as integer expression, and the operation is called integer arithmetic.

When both operands in an arithmetic expression are floating point numbers, theexpression is called floating point expression or real expression, and the operationis called floating point arithmetic or real arithmetic.

The result of an integer arithmetic always have integer value.

The remainder operator (%) requires that both operands be integers and the

second operand be non zero.

The division operator requires the second operand be nonzero.

The result of integer division results in a truncated quotient (i.e. the decimal

portion of the quotient will be dropped).

If a division operation is carried out with two floating point numbers or with one

floating point number and one integer, the result will be a floating point quotient.For example 7.5/5=1.5.

If one of both operands are negative then the addition, subtraction, multiplication,

and division operations will result in values whose signs are determined by theusual rules of algebra.

The result of the remainder operation always gets the sign of first operand. For

examples

If a=14 and b=5 then a % b=4

If a=-14 and b=5 then a % b = -4

If a = -14 and b = 5 then a % b = -4

If a= -14 and b = -5 then a % b = 4 Operands the differ in type may undergo type conversion before the expression

takes on its final value. In general, the final result will be expressed in the highest

precision possible, consistent with the data type of the operands.

For example

Operand 1 Operand 2 Result

Short Int Int

Int Float Float

Double Float Double

Double Int Double

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C Operators Notes

Int Long Long

Relational Operators:

Relational Operators are used in C to compare values, typically in conditional controlstatements. The four relational operators in c are =. There are two equality

operators = = and !=. They are closely associated with the relational operators.

Relational Operator Meaning

< Less than

Greater than

>= Greater than or equal to

Equality Operators Meaning

= = Equal to

!= Not equal to

The double equal sign = = used to compare equality is different from the single equal to

= sign which is used as an assignment operator.These six operators are used to form logical expressions, which represent conditions that

are either true or false. The result of the expressions is of type integer, since true is

represented by the integer value 1 and false is represented by the value 0.

Declarations: int i=3, j=7;flaot f=5.5,g=4.5

Expression Interpretation Value

i< 4 True 1

(i + j g True 1

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C Operators Notes

Using complement operators we can simplify the expressions as

Original Expression Simplified Expression

!(a=b

!(a>b) a=b) a


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C Operators Notes

operator (=) and places its value in the variable on the left. Assignment expressions that

make use of assignment operator have the form:

Identifier = expression;

Where identifier represents a variable and expression represents a constant, a variable ora more complex expression.

Ex: a = 2;Area = length * width;

Note:

If the two operands in an assignment expression are of different data types, then

the value of the expression on the right side of assignment operator will

automatically be converted to the type of the identifier on the left of assignment

operator.

For example

A floating value may be truncated if it is assigned to an integer identifier.

A double value may be rounded if it is assigned to a floating point identifier.

An integer value may be changed if it is assigned to a short integer identifier or to

a character identifier.

Unary Operators:

The operators that act upon a single operand to produce a new value are known as unary

operators. C supports the following unary operators.

Operators:

Minus operator Increment operator ++

Decrement operator - -

Size operator

(type) operator

Minus operator

The most common unary operation is a unary minus, where a numerical constant,

variable or expression is preceded by a minus sign. It is important to note that the unary

minus operation is distinctly different from the arithmetic operator which denotessubtraction (-). The subtraction operator requires two separate operands.

Ex: -123, -qty, -4E-8

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C Operators Notes

Increment and Decrement Operator

The increment operator (++) adds 1 to the operand, whereas the decrement operator (--)subtract 1 from the operand. The increment and decrement operators can each be used in

two different ways, depending on whether the operator is written before or after the

operand. For examplea++; /* operator is written after the operand */

++a; /* operator is written before the operand */

If the operator precedes the operand (e.g., ++a), then it is called pre-increment operator

and the operand will be changed in value before it is used for its intended purpose within

the program. On the other hand, if the operator follows the operand (i.e a++), then it iscalled post-increment operator and the value of the operand will be changed after it is

used.

sizeof Operator:

In C, an operator sizeof is used to calculate size of various datatypes. These can be basic

or primitive datatypes present in the language, as well as the ones, created byprogrammer. The sizeof opearator looks like a function, but it is actually an operator that

returns the length, in bytes. It is used to get size of space any data-element/datatype

occupies in memory. If type name is used, it always needs to be enclosed in parentheses,whereas variable name can be specified with or without parentheses.

Ex:

int i;

sizeof i;sizeof(int);

Type Conversion (Cast Operator)

Rather than let the compiler implicitly convert data, we can convert data from one type to another

by using cast operator. To cast data from one type to another it is necessary to specify type in

parentheses before the value we want to be converted. For example to convert integer variable

count, to a float we code the expression as

(float) count;

Since cast operator is an unary operator, we must put binary expression to be casted in

parentheses to get the correct conversion. For example

(float) (a+b)

One use of the cast is to ensure that the result of a division is a floating point number. In case of

division, proper casting is necessary.

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C Operators Notes

Conditional Expressions

Simple conditional operations can be carried out with the conditional operator (? :). The

conditional operator (? :) is a ternary operator since it takes three operands. The general form of

conditional expression is

Test expression ? expression 1 : expression 2;

Conditional operator works as follows:

The test expression is implicitly converted to Boolean expression. It is evaluated.

If the result of test expression is true(1), the expression 1 is evaluated and the conditional

expression takes on value of expression 1.

If the result of test expression is false (0), the expression 2 is evaluated and the

conditional expression takes on value of expression 2.

Therefore the result of the conditional operator is the result of whichever expression is evaluated the first or the second. Only on of the last 2 expressions is evaluated in a conditional

expression.

Bitwise operators

The bitwise operators are the bit manipulation operators. They can manipulate individual

bits within the piece of data. These operators can operate on integers and characters butnot on floating point numbers or numbers having double data type.

Operator Description Example

~

The bitwise complement operator is an

unary operator. It complements each bit

of the operand.

Operand = 1111 0000 1111 0000

~ operand

ResultedOperand = 0000 1111 0000 1111

&

The bitwise AND operator compares

each bit of its first operand to thecorresponding bit of its second operand.

If both bits are 1, the corresponding

result bit is set to 1. Otherwise thecorresponding bit is set to 0.

Operand 1 = 1111 1111 1111 0000

Operand 2 = 1111 0000 1111 0000

X= operand 1 & operand 2

ThenX= 1111 0000 1111 0000

|

The bitwise inclusive OR operatorcompares each bit of its first operand to

the corresponding bit of its second

operand. If either of bits is 1 the

corresponding result bit is set to 1,otherwise the corresponding bit is set to

0.

Operand 1= 0000 1111 0011 0000Operand 2= 1111 1111 0000 1111

X=operand 1 | operand 2

ThenX= 1111 1111 0011 1111

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C Operators Notes

^

The bitwise exclusive OR operator

compares each bit of its first operand tothe corresponding bit of its second

operand. If one bit is 0 and the other bit

is 1 the corresponding result bit is set to

1 otherwise result bit is set to 0.

Operand 1= 1111 0000 1100 0011

Operand 2= 1111 1111 0011 0011

X= operand 1 ^ operand 2

Then

X= 0000 1111 1111 0000

The bitwise right shift operator is a

binary operator. The first operand is the

value to be shifted and the secondoperand specifies the number of bits to

be shifted.

Operand 1 = 1111 0000 1111 0000

Operand 2 = 2

X = operand 1 >> operand 2X=00 1111 0000 1111 00

Operator Precedence and Associativity

Operator precedence describes the order in which c evaluates different operators in a

complex expression. For example, in the expression a = 4+b*2, which happens first, the

addition or the multiplication? The operator precedence will tell us which operationshould perform first. The operator which is having highest precedence will evaluate first

and the operator which is having lowest precedence evaluate last. If two operators are on

the same level of precedence then the order they will be evaluated in is going to be

considered. This is knows as Associativity property of an operator.

Operator

Type

Operator Description Associativity Precedence

LevelParentheses,

Braces( )[ ]

ParenthesesBrackets

Left to right 1

Unary

++ --

+ -

! ~

(type)

&

Size of

Unary pre increment / predecrement

Unary plus / minus

Unary Logical negation /

bitwise complement

Unary cast

Address

Determine Size in bytes

Right to left 2

Binary* / %

Multiplication / Division/

ModulesLeft to right 3

+ - Addition / Subtraction Left to right 4

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C Operators Notes

>Bitwise shift left, bitwise

shift rightLeft to right 5

< >=

Relational less than / less

than or equal toRelational greater than /

greater than or equal to

Left to right 6

= = !=Relational is equal to / is

not equal toLeft to right 7

& Bitwise AND Left to right 8

^ Bitwise XOR Left to right 9

|Bitwise OR

Left to right 10

&&Logical AND

Left to right 11

||Logical OR

Left to right 12

Ternary ? :

Ternary (Conditional)

Right to left 13

Assignment

=

+= -=

*= /=

%= &=

^= !=

=

Assignment

Addition/Subtraction

AssignmentMultiplication/Division

Assignment

Modulus/bitwise AND

assignmentBitwise exclusive/inclusive

OR assignmentBitwise Shift left/right

assignment

Right to left 14

Comma ,

Comma (separateExpression) Left to right 15

INPUT & OUTPUT STATEMENTS

Reading data, processing it and writing the processed data known as information or a

result of a program are the essential functions of a program. The C is a functionallanguage. It provides a number of macros and functions to enable the programmer to

effectively carry out these input and output operations. Some of the input/output

functions / macros in C are1. getchar() 2. putchar()

3. scanf() 4. printf()

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5. gets() 6. puts()

The data entered by the user through the standard input device and processed data isdisplayed on the standard output device.

I/O Functions:

I / O functions are grouped into two categories.

Unformatted I/O functions

Formatted I/O function.

The Formatted I/O functions allows 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. Amongst the

above specified I/O functions scanf() and printf() are formatted I/O functions.

Function Formatted Unformatted

Input scanf() getchar(),gets()

Output printf() putchar(),puts()

Formatted Output The printf function

C provides the printf function to display the data on the monitor. This function can beused to display any combination of numerical values, single characters and strings. The

general form of printf statement

Function name

Function arguments

printf(my roll number is %d. \n, rollno)

control string print list

The %d is known as a placeholder or conversion character or format code or formatspecifier. At the time of display the value of the specified variable is substituted at the

place of placeholder. In out example, value of rollno is substituted in place of %d. The

printf uses different placeholders to display different type of data items.

Placeholder Type of Data Item displayed

%c Single character

%d Signed decimal integer

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%e Floating point number with an exponent

%f Floating point number without an exponent

%g Floating point number either with exponent or without exponentdepending on value. Trailing zeros and trailing decimal point

will not be displayed.

%i Singed decimal number

%o Octal number, without leading zero

%s String

%u Unsigned decimal integer

%x Hexadecimal number, without leading zero

There are certain letters which may be used as prefix for certain placeholders. These are

h: the h letter can be applied to d,i,o,u and x placeholders. The h letter tells printf() todisplay short integers. As an example, %hu indicates that the data is of type short

unsigned integer.

l: the l letter can be applied to d,i,o,u and x placeholder. The l letter tells printf() to

display long integers. As an example, %ld indicates that the data is of type long integer.

When it is applied to f, it indicates double data type.

L: the L letter, when applied to f indicates long double data type.

Some important points to remember

Control string must be enclosed within the double quotes.

For every data item to be displayed there must be a placeholder corresponding to

its data type.

Multiple placeholders are allowed in the control string. In such a case they may be

contiguous or separated by blank spaces or commas.

The data items must be included in the print list and they must be separated by

commas.

Print list is not enclosed within double quotes.

The comma must be used to separate the format string and the print list.

Formatting integer output

We have seen that how integer numbers can be displayed on the monitor using %d

placeholder. In case of integer numbers, the placeholder can accept modifiers to

specify the minimum field width and left justification by default, all output is right

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justified. We can force the information to be left justified by putting a minus sign

directly after the %. For example

printf statement Output (assume x=1234)

printf(%d,x); 1 2 3 4

printf(%6d,x);1 2 3 4

Right justified

printf(%-6d,x);1 2 3 4

Left justified

As shown in the above examples, if the number width in digits is less than the minimum

field width the empty places are filled with spaces. However if the number width isgreater than the minimum field width, the number is printed in the full, overriding the

minimum field width specification. This is illustrated in the following list.

It is also possible to pad the empty places with zeros. If we want to pad with zeros, we

have to place a zero before the minimum field width specifier.


printf(%3d,x);1 2 3 4

Overriding the minimum field width

printf(%06d,x);0 0 1 2 3 4

Padding with zeros

As shown in the above examples, if the number width in digits is less than the minimumfield width the empty places are filled with spaces. However if the number width is

greater than the minimum field width, the number is printed in the full, overriding the

minimum field width specification. This is illustrated in the following list.

It is also possible to pad the empty places with zeros. If we want to pad with zeros, we

have to place a zero before the minimum field width specifier.

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printf(%3d,x);1 2 3 4

Overriding the minimum field width

printf(%06d,x);0 0 1 2 3 4

Padding with zeros

Formatting floating point output

In case of floating point numbers placeholder can accept modifiers that specify the

minimum field width, precision and left justification. To add a modifier we have to place

a decimal point follower by the precision after the field width specifier. For e and fformats, the precision modifier determines the number of decimal places to be displayed.

For example %8.4f will display a number at least 8 characters wide including decimal

point with four decimal places.

printf statement Output (assume x=3456.12065)

printf(%f,x);3 4 5 6 . 1 2 0 6 5 0

Default precision is 6

printf(%7.2f,x);3 4 5 6 . 1 2

Total 7 characters wide out of 2 are decimal point

printf(%9.2f,x);3 4 5 6 . 1 2

Right justified

printf(%-9.2f,x);3 4 5 6 . 1 2

left justified

printf(%9.3e,x);3 . 4 5 6 E + 0 3

3 decimal places and total 9 characters wide

Formatting String Output

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When the precision is applied to strings, the number preceding period specifies the

minimum field width and the number following the period specifies the number ofcharacters of the string to be displayed. For examples %16.9s will display a string that

will be at least sixteen characters long; however only first nine characters from the string

are displayed with remaining blank characters. Let us see the important points related toformatted string display.

When minimum field width is specified without negative sign, display is right

justified.

When only minimum field width is specified and it is less than the actual string

length, the minimum field width is overridden and complete string is displayed.

We can insert negative sign before minimum field width to get left justified

display.

printf

statement

Output (assume str: THIS IS A TEST STRING

containing 21 characters including blanks.)

printf(%s,str);T H I S I S A T E S T S T R I N G

printf(%24s,str);

T H I S I S A T E S T S T R I N G

printf(%24.14s

,str);

T H I S I S A T E S T

Escape Sequences to enhance the readability of output

The backslash symbol( \ ) is known as escape character. Since the newline character andthe tab character begin with backslash they are called escape sequences. They are

Escape

Sequences

Function

\nNewline : Displays the message or variable values following it on

the next line.

\tTab: Moves cursor to the next tab

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C Operators Notes

\bBackspace: Moves cursor one position to the left of its current

position.

\fForm feed: Advances the computer stationary attached to the

printer to the top of next page.

\Single Quote: Displays single quote

\\Backslash: Displays backslash

\Double Quote: Displays double quote

\rCarriage Return : Takes the cursor to the beginning of the line in

which it is currently placed.

\aAlert: Alerts the user by sounding the speaker inside the computer.

Functions

In structural programming, the program is divided into small independent tasks. These

tasks are small enough to be understood easily without having to understand the entireprogram at once. Each task is designed to perform specific functionality on its own.

When these tasks are performed, their outcomes are combined together to solve the

problem. Such a structural programming can be implemented using modular

programming. In modular programming, the program is divided into separate smallprograms called modules. Each module is designed to perform specific function. Modules

make out actual program shorter, hence easier to read and understand. A defined function

or set of similar functions is coded in a separate module or sub module, which means thatcode can be loaded into memory more efficiently and that modules can be reused in other

programs. After a module has been tested individually, it is then integrated with other

modules into the overall program structure.

Each module can be subdivided according to software engineering principles. The

following structural chart shows the relation between each module and its sub module.Such a design approach is called top-down design.

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Main

Module

Module

1

Module

2

Module

3

Module3A

Module1A

Module2A

Module1B

Module1C

Module2B

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C Operators Notes

The main module is known as a calling module because it has submodule. Each of the

sub module is known as called modules. However, modules 1, 2 and 3 also have sub

modules therefore they are also calling modules. The communication between modulesin a structure chart is allowed only through a calling module. If module 1 need to send

data to module 2, the data must be passed through the calling module, main module. No

communication can take place directly between modules that do not have a clling-called

relationship. This means that in a structural chart, a module can be called by one and onlyone higher module.

There are several advantages of modular / structural programming, some of them are

Reusability: Many programs require that a particular group of instructions accessedrepeatedly, from several different places within the program. The repeated instructions

can be placed within a single function, which can then be accessed wherever it is needed.

This avoids rewriting of group of instructions on every access.

Easy Debugging: Since each function is smaller and has a logical clarity, it is easy to

locate and correct errors in it.

Build Library: The use of functions allows a programmer to build a customizedlibrary of frequently used routines or system-dependent features. Each routine can

programmed as a separate function and stored within a special library file. Buildinglibraries reduce the time and space complexity and promote the portability.

Basics of Functions

A function by definition, is a procedure or routine. In other words, its a self-contained

block of code that executes a certain task. Although some languages do distinguish

between procedure and function, whereas a function returns a value of some kind and aprocedure does not, C combines both functionalities into its definition. In order to use

function in the program we need to establish 3 elements that are related to the function.

Function Declaration: All identifiers in C need to be declared before they are

used. This is true for functions as well as variables. For functions the declarations

needs to be before the first call of the function.

JNTUWORLD20


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C Operators Notes

Function Definition: It is actual code for the function to perform the specific

task.

Function Call: In order to use function in the program we use function call to

access the function. The program or function that calls the function is referred toas calling program or calling function.

Ex:

#include

print_msg(); /* The function Declaration */

void main() /* the main function */{

print_msg(); /* The function call */

}

print_msg() /* the function definition */

{

printf(this is a module called print_msg \n);

}

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