C PROGRAMMING ARRAYS
In C programming, one of the frequently arising problem is to handle
similar types of data. For example: If the user want to store marks of 100
students. This can be done by creating 100 variable individually but, this
process is rather tedious and impracticable. These type of problem can be
handled in C programming using arrays.
An array is a sequence of data item of homogeneous value(same type).
Arrays are of two types:
- One-dimensional
arrays
- Multidimensional
arrays( will be discussed in next chapter )
Declaration of
one-dimensional array
data_type array_name[array_size];
For example:
int age[5];
Here, the name of array is age. The size of array is
5,i.e., there are 5 items(elements) of array age. All element in an
array are of the same type (int, in this case).
Array elements
Size of array defines the number of elements in an array. Each
element of array can be accessed and used by user according to the need of
program. For example:
int age[5];
Note that, the first element is numbered 0 and so on.
Here, the size of array age is 5 times the size of int
because there are 5 elements.
Suppose, the starting addres of
age[0] is 2120d and the
size of int be 4 bytes. Then, the next address (address of a[1]) will
be 2124d, address of a[2] will be 2128d and so on.
Initialization
of one-dimensional array:
Arrays can be initialized at declaration time in this source
code as:
int age[5]={2,4,34,3,4};
It is not necessary to define the size of arrays during
initialization.
int age[]={2,4,34,3,4};
In this case, the compiler determines the size of array by
calculating the number of elements of an array.
Accessing array
elements
In C programming, arrays can be accessed and treated like variables
in C.
For example:
scanf("%d",&age[2]);
/* statement to insert value in the third element of array age[]. */
scanf("%d",&age[i]);
/* Statement to insert value in (i+1)th element of array age[]. */
/* Because, the first element of array is age[0], second is age[1], ith is age[i-1] and (i+1)th is age[i]. */
printf("%d",age[0]);
/* statement to print first element of an array. */
printf("%d",age[i]);
/* statement to print (i+1)th element of an array. */
Example of array in C programming
/* C program to find the sum marks of n students using arrays */
#include <stdio.h>
int main(){
int marks[10],i,n,sum=0;
printf("Enter number of students: ");
scanf("%d",&n);
for(i=0;i<n;++i){
printf("Enter marks of student%d: ",i+1);
scanf("%d",&marks[i]);
sum+=marks[i];
}
printf("Sum= %d",sum);
return 0;
}
Output
Enter number of students: 3
Enter marks of student1: 12
Enter marks of student2: 31
Enter marks of student3: 2
sum=45
Important thing to remember in C arrays
Suppose, you declared the array of 10 students. For example:
arr[10]. You
can use array members from arr[0] to arr[9]. But, what if you want to use element arr[10], arr[13] etc.
Compiler may not show error using these elements but, may cause fatal error
during program execution.
C Programming Multidimensional Arrays
C programming language allows to create arrays of arrays known as
multidimensional arrays. For example:
float a[2][6];
Here, a is an array of two dimension, which is an example
of multidimensional array. This array has 2 rows and 6 columns
For better understanding of multidimensional arrays, array elements
of above example can be thinked of as below:
Initialization of
Multidimensional Arrays
In C, multidimensional arrays can be initialized in different number
of ways.
int c[2][3]={{1,3,0}, {-1,5,9}};
OR
int c[][3]={{1,3,0}, {-1,5,9}};
OR
int c[2][3]={1,3,0,-1,5,9};
Initialization
Of three-dimensional Array
double cprogram[3][2][4]={
{{-0.1, 0.22, 0.3, 4.3}, {2.3, 4.7, -0.9, 2}},
{{0.9, 3.6, 4.5, 4}, {1.2, 2.4, 0.22, -1}},
{{8.2, 3.12, 34.2, 0.1}, {2.1, 3.2, 4.3, -2.0}}
};
Suppose there is a multidimensional array
arr[i][j][k][m]. Then this array can hold i*j*k*m numbers of data.
Similarly, the array of any dimension can be initialized in C
programming.
Example of Multidimensional Array In C
Write a C
program to find sum of two matrix of order 2*2 using multidimensional arrays
where, elements of matrix are entered by user.
#include <stdio.h>
int main(){
float a[2][2], b[2][2], c[2][2];
int i,j;
printf("Enter the elements of 1st matrix\n");
/* Reading two dimensional Array with the help of two for loop. If there was an array of 'n' dimension, 'n' numbers of loops are needed for inserting data to array.*/
for(i=0;i<2;++i)
for(j=0;j<2;++j){
printf("Enter a%d%d: ",i+1,j+1);
scanf("%f",&a[i][j]);
}
printf("Enter the elements of 2nd matrix\n");
for(i=0;i<2;++i)
for(j=0;j<2;++j){
printf("Enter b%d%d: ",i+1,j+1);
scanf("%f",&b[i][j]);
}
for(i=0;i<2;++i)
for(j=0;j<2;++j){
/* Writing the elements of multidimensional array using loop. */
c[i][j]=a[i][j]+b[i][j]; /* Sum of corresponding elements of two arrays. */
}
printf("\nSum Of Matrix:");
for(i=0;i<2;++i)
for(j=0;j<2;++j){
printf("%.1f\t",c[i][j]);
if(j==1) /* To display matrix sum in order. */
printf("\n");
}
return 0;
}
Ouput
Enter the elements of 1st matrix
Enter a11: 2;
Enter a12: 0.5;
Enter a21: -1.1;
Enter a22: 2;
Enter the elements of 2nd matrix
Enter b11: 0.2;
Enter b12: 0;
Enter b21: 0.23;
Enter b22: 23;
Sum Of Matrix:
2.2 0.5
-0.9 25.0
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