SlideSet_4_Arraysnew.pdf

❖ An array is simply a collection of variables of the
same data type that are referred to by a common name.
❖ A specific element in an array is accessed by an index.
❖ All array consist of contiguous memory locations
where the lowest address corresponds to the first
element whereas the highest address corresponds to
the last element.
Arrays

❖ The first element in the array is numbered 0, so the last
element is 1 less than the size of the array.
❖ An array is also known as a subscripted variable.
❖ Before using an array its type and dimension must be
declared.
❖ Index always starts from 0 in an array.
Arrays

An array of one dimension is known as a one-
dimensional array or 1-D array
One-dimensional Arrays

Like other variables an array needs to be declared so that the
compiler will know what kind of an array and how large an
array we want.
type arr_name[size];
Here type is any valid data type,
arr_name is the name of the array you give
and size is the array size.
In other word, size specify that how many element,
array can hold.

e.g.
int marks[30] ;
Here, int specifies the type of the variable,
The number 30 tells how many elements of the type int will
be in our array. This number is often called the "dimension"
of the array.
The bracket i.e. [ ] tells the compiler that we are dealing
with an array.

Initializing Array in C
int num[6] = { 2, 4, 12, 5, 45, 5 } ;
int n[ ] = { 2, 4, 12, 5, 45, 5 } ;
float press[ ] = { 12.3, 34.2, -23.4, -11.3 } ;
int b[ 100 ], x[ 27 ];

❖ This is done with subscript, the number in the brackets
following the array name.
❖ This number specifies the element’s position in the array.
❖ All the array elements are numbered, starting with 0.
❖ Thus, arr [2] is not the second element of the array, but the
third.
int arr[ ] = {1, 2, 3, 4, 5};
val = arr[2]; // val=3
Accessing Elements of an Array

• Array elements are like normal variables
c[ 0 ] = 3;
printf( "%d", c[ 0 ] );
– Perform operations in subscript. If x equals 3
c[5-2]==c[3]==c[x]

1-D Array Input/Output
/* Program to take 5 values from the user and store them in an array
& Print the elements stored in the array*/
#include <stdio.h>
int main() {
int values[5];
printf("Enter 5 integers: ");
// taking input and storing it in an array
for(int i = 0; i < 5; ++i)
{
scanf("%d", &values[i]);
}

1-D Array Input/Output
// printing elements of an array
for(int i = 0; i < 5; ++i)
{
printf("%dn", values[i]);
}
return 0;
}

/*Compute the sum of the elements of the array */
#include <stdio.h>
int main( void )
{ /* use initializer list to initialize array */
int a[12] = { 1, 3, 5, 4, 7, 2, 99, 16, 45, 67, 89, 45 };
int i; /* counter */
int total = 0; /* sum of array */
/* sum of contents of array a */
for ( i = 0; i < SIZE; i++ )
{
total += a[ i ];
} /* end for */
printf( "Total of array element values is %dn", total );
return 0;
} Output : Total of array element values is 383

Passing a single array element to a function
#include<stdio.h>
void display(int a);
int main()
{
int myArray[] = { 2, 3, 4 };
display(myArray[2]); //Passing array element myArray[2] only.
return 0;
}
void display(int a)
{
printf("%d", a);
}
OUTPUT
4

Passing 1-d array to function using call by value method
#include <stdio.h>
int main()
{
char arr[] = {'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i',
'j'};
for (int x=0; x<10; x++)
{
/* I’m passing each element one by one
using subscript*/
disp (arr[x]);
}
return 0;
}
void disp( char ch)
{
printf("%c ", ch);
}
OUTPUT:
a b c d e f g h i j

Passing a 2D array as a parameter
#include<stdio.h>
void displayArray(int arr[3][3]);
int main()
{
int arr[3][3], i, j;
printf("Please enter 9 numbers for
the array: n");
for (i = 0; i < 3; ++i)
{
for (j = 0; j < 3; ++j)
{
scanf("%d", &arr[i][j]);
}
}
// passing the array as argument
displayArray(arr);
return 0;
}
void displayArray(int arr[3][3])
{
int i, j;
printf("The complete array is: n");
for (i = 0; i < 3; ++i)
{
// getting cursor to new line
printf("n");
for (j = 0; j < 3; ++j)
{
printf("%dt", arr[i][j]);
}
}
}

Practice question:
Find maximum and minimum element in
an array

Find maximum and minimum element in an array
#include <stdio.h>
int main()
{
int arr1[100];
int i, max, min, n;
printf("Input the number of elements to be stored in the array :");
scanf("%d",&n);
printf("Input %d elements in the array :n",n);
for(i=0;i<n;i++)
{
printf("element - %d : ",i);
scanf("%d",&arr1[i]);
}

Find maximum and minimum element in an array
max = arr1[0];
min = arr1[0];
//finding max
for(i=1; i<n; i++)
{
if(arr1[i]>max)
{
max = arr1[i];
}
//finding min
if(arr1[i]<min)
{
min = arr1[i];
}
}
}

Practice question:
Insert an element in an Array

// position at which element
// is to be inserted
pos = 5;
// increase the size by 1
n++;
// shift elements forward
for (i = n; i >= pos; i--)
arr[i] = arr[i - 1];
// insert x at pos
arr[pos - 1] = x;
// print the updated array
for (i = 0; i < n; i++)
printf("%d ", arr[i]);
printf("n");
return 0;
}
// C Program to Insert an element at a
//specific position in an Array
#include <stdio.h>
int main()
{
int arr[100];
int i, x, pos, n = 10;
// initial array of size 10
for (i = 0; i < 10; i++)
scanf(“%d”, &arr[i]);
// print the original array
for (i = 0; i < n; i++)
printf("%d ", arr[i]);
printf("n");
// element to be inserted
x = 50;

Multidimensional
Arrays
COMPUTER
PROGRAMMING

Multiple-Subscripted Arrays
➢ Multiple subscripted arrays
– Tables with rows and columns (m by n array)
– Like matrices: specify row, then column
➢Declaration of two-dimensional array in C:
int arr[10][5];
• So the above array have 10 rows and 5 columns.
Multidimensional Arrays

Double-subscripted array (2-D) with three rows and four
column.
Two- Dimensional Arrays

➢Initialization
int arr[ 2 ][ 2 ] = { { 1, 2 }, { 3, 4 } };
– Initializers grouped by row in braces

➢Initialization
– If not enough, unspecified elements set to
zero
int arr[ 2 ][ 2 ] = { { 1 }, { 3, 4 } };
➢Referencing elements
– Specify row, then column
printf( "%d", arr[ 0 ][ 1 ] );

/* Example- initializing and displaying elements*/
#include<stdio.h>
void main()
{
int arr[10][5];
int i, j;
// e.g. initializing 2-D array elements by 1
for(i=0; i<10; i++)
{
for(j=0; j<5; j++)
{
arr[i][j] = 1;
}
}
Cont….

// displaying 2-D array
for(i=0; i<10; i++)
{
for(j=0; j<5; j++)
{
printf("arr[%d][%d]=%dt", i, j, arr[i][j]);
}
printf("n");
}
}
Cont….

Entering and displaying Matrix elements
#include<stdio.h>
void main()
{
int arr[5][3];
int i, j;
printf("Enter 5*3 Matrix: ");
for(i=0; i<5; i++)
{
for(j=0; j<3; j++)
{
scanf("%d", &arr[i][j]);
}
}
Cont….
Matrix

//Displaying the Matrix
printf("nThe Matrix is:n");
for(i=0; i<5; i++)
{
for(j=0; j<3; j++)
{
printf("%dt", arr[i][j]);
}
printf("n");
} }
Cont….

Addition of two Matrices
Matrix

Step 1 - Read the search element from the user.
Step 2 - Compare the search element with the first element in the list.
Step 3 - If both are matched, then display "Given element is found!!!"
and terminate the function
Step 4 - If both are not matched, then compare search element with
the next element in the list.
Step 5 - Repeat steps 3 and 4 until search element is compared with
last element in the list.
Step 6 - If last element in the list also doesn't match, then display
"Element is not found!!!" and terminate the function.
Linear Search

#include <stdio.h>
int main()
{
int array[100], search, c, n;
printf("Enter number of elements in arrayn");
scanf("%d", &n);
printf("Enter %d integer(s)n", n);
//Entering array elements
for (c = 0; c < n; c++)
scanf("%d", &array[c]);
//Enter number to be searched
printf("Enter a number to searchn");
scanf("%d", &search);
Linear Search

//Linear search
for (c = 0; c < n; c++)
{
if (array[c] == search)
// If required number is found
{ printf("%d is present at location %d.n", search, c+1);
break;
}
}
// for not found
if (c == n)
printf("%d isn't present in the array.n", search);
return 0;
}
Linear Search

Practice questions:
• Deletion of an array element
• Merging two arrays

SlideSet_4_Arraysnew.pdf

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