C Arrays Function

7/31/2019 C Arrays Function

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An array is a collection of variables ofsimilardatatype.

A specific element in an array is accessed by an index.

Arrays may have from one to several dimensions.

In C, all arrays consist of contiguous memorylocations.

The lowest address corresponds to the first elementand the highest address to the last element.

Integer array of 4 elements

1000 1002 1004 1006

ARRAYS


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Single dimension Arrays The general form of declaring an array is

[size];

Eg:

int marks[5];

The values are accessed by the indexes.

Eg:

marks[0]=90;marks[1]=95;

marks[2]=98;

marks[3]=85;

marks[4]=80;


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Example/* Program using arrays */

#include#include

void main(){int arr[5],i; //declaring array variable of size 5clrscr();for(i=0;i


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Memory mapping

arr[0] arr[1] arr[2] arr[3] arr[4]

1 2 3 4 5


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Multi dimensional Array

C supports multidimensional arrays.

The exact limit, if any, is determined by the compiler.

The general form of a multidimensional array declarationis

[size1][size2][size3][sizen];


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Two dimensional Array

The simplest form of the multidimensional array is the

two-dimensional array. The declaration syntax is

[size][size];

LeftIndex Right Index


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Example/* Program for two dimensional array */

#include#includevoid main()

{ int t, i, num[3][4];for(t=0; t


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Memory mapping

num[t][i]

0 1 2 3

0 1 2 3 4

1 5 6 7 8

2 9 10 11 12


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Example/* Matrix Addition */#include

#include

void main()

{

int mat1[3][3];

int mat2[3][3];

int mat[3][3];

int i,j,k,l;

printf("\nGive the values for 1st Matrix: \n);for(i=0;i


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printf("\nGive the values for 2nd Matrix:\n);

for(i=0;i


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Array Initialization C allows the initialization of arrays at the time of their

declaration.

Syntax [size1]. . .[sizeN]={value_list};

Eg:int i[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

Thevalue_list is a comma-separated list of values whose typeis compatible with data type.


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Array InitializationWe can initialize the multi dimensional arrays also.

Eg:int sqr[3][2] = {1,1,2,4,3,9};

Another way

int sqr[3][2] = {{1,1},{2,4},{3,9}};

This is called Sub aggregate Grouping


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Functions


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Function

Function is basic requirement of modularprogramming.

The process of dividing a large program into small subprograms and manipulating them independently isknown as modular programming.

A function is a named, independent, block ofstatements that perform well defined, specific taskand may return a value.


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Example/* Program for simple function call */

#include

void main(){

message(); //Function Call

printf("\nCry, and you stop the monotony!");

}

message() //Function

{

printf("\nSmile,and the world smiles with you...");

}


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Types of Function Pre-defined functions User defined functions

Pre-defined functions

The functions, which has special type ofmeaning which isalreadydefined and stored, is called built-in functions orpre-defined functions.

Eg:

int a=4;x=pow(a,2);

User defined functions

Can be createdbytheuseror programmer for performing

specific task.


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Any C program contains at least one function.

If a program contains only one function, it must be main( ). If a C program contains more than one function, then one (and

only one) of these functions must be main( ), because programexecution always begins with main( ).

There is no limit on the number of functions that might bepresent in a C program.

Each function in a program is called in the sequence specified bythe function calls in main( ).

After each function has done its thing, control returns to main().

When main( ) runs out of function calls, the program ends.


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Structure of Function(arg 1,arg 2,,arg n)

{

declaration part;

statements;

return;}


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Exampleint sum(int x,int y){

int result;result = x + y;return (result);

}


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Properties Every function has a uniquename. This name is used to

call the function from main() function.

A function can be calledfrom within anotherfunction.

A function is independent and it can perform its taskwithout intervention from or interfering with other partsof the program.

A function returns a value to the calling program. This isoptional and depends upon the task.


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Example

#include

void main()

{

printf("\nI am in main");

italy();

printf("\nI am finally back in main");

}

italy(){

printf("\nI am in italy");

brazil();

printf("\nI am back in italy");

}


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brazil()

{

printf("\nI am in brazil");

argentina();}

argentina()

{

printf("\nI am in argentina");

}


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Rules A function gets called when the function name is followed

by a semicolon.main()

{func();

}

A function is defined when function name is followed by apair of braces in which one or more statements may bepresent.

func(){

statement 1 ;statement 2 ;statement 3 ;

}


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Rules

A function can be called any number of times.

main()

{display() ;

display() ;

}

display()

{

printf("\n Learning C is very Easy");

}


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Rules

The order in which the functions are defined in a programand the order in which they get called need not necessarilybe same.main()

{

display1() ;display2() ;}

display2(){

printf("\n Called Later ");}

display1(){

printf("\n Called First ");

}


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Rules

A function can call itself. This is known as Recursion.

int fact(int n)

{

if(n==0)

return(1);

return(n*fact(n-1));

}Note: This function is known as RecursiveFunction.


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Parts of the Function

Function prototype declaration

Definition of a function

Function call

Actual and formal arguments

The return statement


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Parts of the Function Function prototype:

It helps the compiler to check the return and argumenttypes of the function.

Function prototype declaration consists of Function return type

Name

Arguments list

Ex:void show(void);

int sum(int,int);

float sum(float,int);


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Function Definition:

The block of statement followed by functiondeclarator is called as function definition.

The declarator and function prototypedeclaration should match each other.

Function Call:A function is called by its name followed by

arguments list enclosed in parenthesis andterminated by semi-colon.


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Parts of the FunctionActual and formal arguments:

The arguments declared in calling function arecalled actual arguments.

The arguments declared in function declaratorare called formal arguments.

The return statement:

The return statement is used to return the value tocaller function.

The return statement returns only one value at atime.

Syntax : return (variable name);


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void main()

{

int sum(int,int);

int a=10,b=20,c;

c=sum(a,b);

}

int sum(int x,int y)

{ return(x+y);

}

Function Prototype

Function call

Actual arguments

Function declarator

Function definition

Return statement

Formal arguments



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Types of Function

A function may belong to any one of the followingcategories:

1. Functions with no arguments and no return values.

2. Functions with arguments and no return values.

3. Functions with arguments and return values.

4. Function with no arguments and return values.


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Functions with no arguments and no return values This is the simplest function ,it does not receive any

arguments from the called function and does notreturn any value from calling function.

Types of Function


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#include

void main()

{

void show();

show();

}

void show()

{

printf(Hi);

}

Example


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Functions with arguments and no return values This function receives arguments from calling

function and does not return value to the callingfunction.

Types of Function


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/* Example for with argument no returnvalue*/

#include

#include

void main()

{

void line(char,int);

line(*,20); //function call

printf(\n Welcome to KGISL - iTech);

line(&,20); //function call

getch();

}

Example


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void line(char ch,int n)

{

int i;

for(i=0;i


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#include

#include

void add(int x,int y)

{

int result;

result = x+y;printf("Sum of %d and %d is %d.\n\n",x,y,result);

}

void main()

{

clrscr();add(17,95); //call 1

add(59, 344); //call 2

add(198,7895); //call 3

getch();

}

Example

There is no

function prototype


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Functions with arguments and return values This function receives arguments from calling

function and returns the computed value back to thecalling function.

Types of Function


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#include

#include

int sum(int,int); //function prototype

void main(){

int i,j,k;

clrscr();

printf(Enter value of i and j:);scanf(%d%d,&i,&j);

k=sum(i,j); //function call

Example


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printf(\n Sum is:%d,k);getch();

}

/* function definition for adding twonumbers */

int sum(int a,int b){

int c;c = a+b;return c;

}


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Functions with no arguments and return values

Types of Function


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Function Call

There are two ways to call a function.

1. Call byValue

2. Call byReference


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Example for Call by Value#include

#include

int main()

{int x,y;

clrscr();

printf("Enter x and y value:");

scanf("%d%d",&x,&y); //getting valuesprintf("\nBefore swapping:x=%d y=%d",x,y);

swap(x,y); //Passing the values

return 0;


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int swap(int a,int b)

{

int c;

c=a;a=b;

b=c;

printf("\n after swapping:a=%d b=%d",a,b);

return 0;

}


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Example for Call by Reference

#include#include

int main()

{

int x,y;clrscr();

printf("Enter x and y value:");

scanf("%d%d",&x,&y);

printf("\nBefore swapping:x=%d y=%d",x,y);

swap(&x,&y); //Passing addresses

return 0;

}


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int swap(int *a,int *b){

int c;

c=*a;*a=*b;

*b=c;

printf("\nAfter swapping:a=%d b=%d",*a,*b);

return 0;}


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Advantages of Function Support for modular programming.

Reduction in program size.

Code duplication is avoided.

Code reusability is provided.

Functions can be called repetitively.

A set of functions can be used to form Libraries.

Individual functions can be easily built,tested.


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Pointers


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Pointers Pointers provide the means by which functions can

modify their calling arguments.

Pointers support dynamic allocation.

Pointers can improve the efficiency of certain routines.


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What are pointers?

Apointeris a variable that holds a memory address.

This address is the location of another object (typicallyanother variable) in memory.

Memory Address

1000

1001

1002

1003

1004

Variable in memory

1003

.

.

.Memory


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Declaration of Pointer Syntax:

*;

The base type of the pointer defines what type ofvariables the pointer can point to.


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Pointer Operators There are two special pointer operators: *and &. The &(Referencing Operator) is a unary operator that

returns the memoryaddress of its operand.

m=&count;* (De-referencing Operator) is the complement of&.

It is a unary operator that returns thevalue located atthe address that follows.

q=*m;

count m q2000

1002

1002 2000


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Example/* Program for pointers */

#include#include

void main(){int a,*p;clrscr();

printf("Enter a:);

scanf(%d,&a);p=&a;printf(\na: %d \np: %d \nvalue: %d,a,p,*p);getch();

}


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The void type of pointer is a special type of pointer.

In C, void represents the absence of type.

So void pointers are pointers that point to a valuethat has no type.

Void Pointers


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int a;

int v1;

void *ptr;

a=100;

ptr=&a;

v1=*(int*)ptr; //defining the type


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Example-1

int a,v1;char b,v2;void *ptr;

a=100;ptr=&a;v1=*(int*)ptr; //now it s pointing to integerprintf(" %d \n ",v1);

b='S';ptr=&b;v2=*(char*)ptr; //now it s pointing to characterprintf(" %c \n ",v2);


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Example-2

#include#includevoid display(int x,void *y){

int a;

char b;if(x==1){

a=*(int*)y;printf("Integer Value %d \n ",a);

}if(x==2){

b=*(char*)y;printf("Character Value %c \n ",b);

}

}


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void main(){int s1;char s2;void *ptr1;

clrscr();s1=300;ptr1=&s1;display(1,ptr1); //function call with int values2='J';

ptr1=&s2;display(2,ptr1);//function call with char valuegetch();}


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Pointer ExpressionAssignment

int var,*p1,*p2;

p1=&var;

p2=p1;

In this pointers p1 and p2pointsto the samevariablevar.

Arithmetic

int var,*p;

p=&var;

p++; // or p--;

In this pointer moves to the next memory location


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Pointer with Array Syntax:

int *ptr;

int sample[5];

ptr=sample;

It can also use & operator to specify the address of

1st element.ptr=&sample;

Note: Pointers can be arrayed like any other data type.


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Example-1

#includevoid main(){int *p,i=0;int x[5]={5,9,6,3,7};

p=x; //initializing with base addressprintf(Element\tValue\tAddress\n\n);while(i


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#include

void main()

{

int a[4],v1,v2,*ptr;a[0]=100;

a[1]=200;

a[2]=300;

a[3]=400;

ptr=a;

printf(" \n %d ",*ptr);

ptr++;

printf(" \n %d ",*ptr);

v1=*(ptr+1);printf(" \n %d ",v1);

ptr++;

v2=*(ptr-1);

printf(" \n %d ",v2);

}

Example-2


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Multiple Indirection

Multipleindirection or pointerstopointers is a pointerpoint to another pointer that points to the target value.

Eg:

float bal;

float *balance,**newbalance;

balance=&bal;

newbalance=&balance; Multiple indirection can be carried on to whatever

extent required.

More than a pointer to a pointer is rarely needed.

C Arrays Function

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