Arrays are the linear data structure and stores same types of data in continuous memory location. Arrays are best used to store data in continuous memory location. However array can have definite size of data. Maximum size of an array must be set while declaring the array.

An array can be defined as below,

image

Diagrammatically myarray can be shown as below,

Note : sorry for typo error in below image, last memory location is 2064H not 2060H sorry !!!!

clip_image002

Some information about above array can be drawn as below,

  • Name of the array is myarray.
  • This is an integer array
  • Size of the array is 5
  • Base address of array is 2000H
  • One element takes 2 bytes in memory. I am assuming we are using language C, so an integer takes 2 bytes in memory.
  • 0,1,2,3,4 are index of the array
  • 99, 13,77,567,9 are elements of the array.
  • You can say 77 is array element at 2nd position of the array.
  • Notation to fetch array elements is as below,

myarray[2]=77

If you need to find memory location of 20th element in above array then you can get that using below formula,

Base Memory location + (Memory size of elements * (Element Position -1))

In above case,

  • Base memory location = 2000H
  • Size of elements = 16 Bits
  • Element position = 20

Memory location of 20th element = 2000 + (16 * (20-1)) = 2000 + 16 *19 = 2304H

On an array usually below native operations can be performed

  • Traversing an array
  • Search an element in array
  • Insert an element at given position in array
  • Delete and element from a given position in array
  • Reverse an array

Array in C

In C we can create an array as below,

clip_image002[6]

We created three different types of array. They are as below,

image

You can store values in array as below,

image

And you can print them as below,

image

Traversing an Array

Traversing an array means iterate through each element of the array once and perform some operation on each element.

image

In above pseudo code K is a variable, A is array and N is upper limit of the array. In C a function to traverse an array and print all the elements can be as below,


int  traverse(int *myarray)
{
int i;
for(i=0;i<5;i++)
{
printf("%d\n",myarray[i]);
}
return 0;
}

And in the main function array is declared as below,


#include<stdio.h>
#include<conio.h>
void main()
{
int myarray[5];
myarray[0]=9;
myarray[4]=99;
traverse(myarray);
getch();
}

You should get output as below,

image

You can see in the output that for 2nd, 3rd and 4th position elements are having some garbage value because we did not assign any values to these positions in array.

Insert in Array

You can insert an element to a given position in array following below algorithm. Let us say,

  • K: position to insert element
  • Element: element to insert
  • N : Size of the array
  • A : Name of the array

image

In C function to insert an element in given position in array can be written as below,


int insertelement(int *myarray, int position, int element)
{
int i;
for(i=4;i>=position;i--)
{
myarray[i]=myarray[i-1];

}
myarray[i]=element;
return 0;
}

And in main function you can call this function as below,


#include<stdio.h>
#include<conio.h>
#define MAX 5
void main()
{
int myarray[5];
myarray[0]=9;
myarray[4]=99;
traverse(myarray);
insertelement(myarray,2,99);
traverse(myarray);
getch();
}

When you run above program you will find 99 has been inserted at 2nd position as below,

image

You will notice all the elements after 2nd position has been shifted by one place.

Delete in Array

You can delete an element to a given position in array following below algorithm. Let us say,

  • K: position to delete element
  • N : Size of the array
  • A : Name of the array

image

In C you can write a function to delete and element from specified position as below,


int deleteelement(int *myarray,int position)
{
int i;
for(i=position; i<5; i++)
{
myarray[i-1]=myarray[i];
}
myarray[i-1]=0;
return 0;
}

Search in Array

There are two types of search you can perform on an array,

  1. Linear Search
  2. Binary Search

Binary search works on divide and conquer algorithm principal and I will take this topic separate in other blog post. Linear search can be performed as below,


int search(int *myarray, int element)
{
int i;
int flag=0;
for(i=0;i<5;i++)
{
if(myarray[i]==element)
{
flag=1;
return i+1;
break;
}
}
if(flag==0)
{
return 0;
}
}

In this way you can start working with arrays in C. in further post I will show you how to work with pointers and array together. Thanks for reading.

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3 thoughts on “Arrays in C

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