Array

C Array

Array in C language is a collection or group of elements (data). All the elements of c array are homogeneous (similar). It has contiguous memory location.
An araay is a data structure in C, that can store a fixed size sequential collection of elements of samw data type.
it can be one dimensional , two dimensional and multidimensional.

Advantage of C Array

1) Code Optimization: Less code to the access the data.
2) Easy to traverse data: By using the for loop, we can retrieve the elements of an array easily.
3) Easy to sort data: To sort the elements of array, we need a few lines of code only.
4) Random Access: We can access any element randomly using the array.

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Disadvantage of C Array

1) Fixed Size: Whatever size, we define at the time of declaration of array, we can't exceed the limit. So, it doesn't grow the size dynamically like LinkedList which we will learn later.

Declaration of C Array

We can declare an array in the c language in the following way.

1. data_type array_name[array_size];  

Now, let us see the example to declare array.

1. int marks[5];  

Here, int is the data_type, marks is the array_name and 5 is the array_size.

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Initialization of C Array

A simple way to initialize array is by index. Notice that array index starts from 0 and ends with [SIZE - 1].

1. marks[0]=80;//initialization of array  
2. marks[1]=60;  
3. marks[2]=70;  
4. marks[3]=85;  
5. marks[4]=75;  

C array example

1. #include <stdio.h>    
2. #include <conio.h>    
3. void main(){    
4. int i=0;  
5. int marks[5];//declaration of array  
6. clrscr();    
7.   
8. marks[0]=80;//initialization of array  
9. marks[1]=60;  
10. marks[2]=70;  
11. marks[3]=85;  
12. marks[4]=75;  
13.   
14. //traversal of array  
15. for(i=0;i<5;i++){    
16. printf("%d \n",marks[i]);  
17. }//end of for loop  
18.   
19. getch();    
20. }    

Output

80  60  70  85  75  

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C Array: Declaration with Initialization

We can initialize the c array at the time of declaration. Let's see the code.

1. int marks[5]={20,30,40,50,60};  

In such case, there is no requirement to define size. So it can also be written as the following code.

1. int marks[]={20,30,40,50,60};  

Let's see the full program to declare and initialize the array in C.

1. #include <stdio.h>    
2. #include <conio.h>    
3. void main(){    
4. int i=0;  
5. int marks[5]={20,30,40,50,60};//declaration and initialization of array  
6. clrscr();    
7.   
8. //traversal of array  
9. for(i=0;i<5;i++){    
10. printf("%d \n",marks[i]);  
11. }  
12.   
13. getch();    
14. }    

Output

20  30  40  50  60  

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Two Dimensional Array in C

The two dimensional array in C language is represented in the form of rows and columns, also known as matrix. It is also known as array of arrays or list of arrays.
The two dimensional, three dimensional or other dimensional arrays are also known as multidimensional arrays.

Declaration of two dimensional Array in C

We can declare an array in the c language in the following way.

1. data_type array_name[size1][size2];  

A simple example to declare two dimensional array is given below.

1. int twodimen[4][3];  

Here, 4 is the row number and 3 is the column number.

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Initialization of 2D Array in C

A way to initialize the two dimensional array at the time of declaration is given below.

1. int arr[4][3]={{1,2,3},{2,3,4},{3,4,5},{4,5,6}};  

Two dimensional array example in C

1. #include <stdio.h>    
2. #include <conio.h>    
3. void main(){    
4. int i=0,j=0;  
5. int arr[4][3]={{1,2,3},{2,3,4},{3,4,5},{4,5,6}};  
6. clrscr();    
7.   
8. //traversing 2D array  
9. for(i=0;i<4;i++){  
10.  for(j=0;j<3;j++){  
11.    printf("arr[%d] [%d] = %d \n",i,j,arr[i][j]);  
12.  }//end of j  
13. }//end of i  
14.   
15. getch();    
16. }    

Output

arr[0][0] = 1  
arr[0][1] = 2  
arr[0][2] = 3  
arr[1][0] = 2  
arr[1][1] = 3  
arr[1][2] = 4  
arr[2][0] = 3  
arr[2][1] = 4  
arr[2][2] = 5  
arr[3][0] = 4  
arr[3][1] = 5  
arr[3][2] = 6