1. Array INTRODUCTION ONE-DIMENSIONAL ARRAY MULTIDIMENSIONAL ARRAY

2. Introduction  An array is a sequence of homogenous elements  It holds multiple values of same type.  Each block of array is stored consecutively in memory. SYNTAX: data-type name[size]; Example: int a[6]; Arrays always start with 0 and end with [size-1]

3. One dimensional Array An array is a data structure consisting of a collection of elements (values or variables), each identified by at least one array index SYNTAX: data-type name[index]; EXAMPLE: int num[10];

4. Initialization  int num[6]={2,4,6,7,8,12};  Individual elements can also be initialize as:  num[0]=2;  num[1]=4;  num[2]=6;  num[3]=7;  num[4]=8;  num[5]=12; A specific element in an array is accessed by an index.

5. Arrays: Example #include<stdio.h> #include<conio.h> int main() { age[0] 25 int age[3]; 30 age[1] age[0] = 25; age[1] = 30; age[2] = 35; 35 for (int j=0; j<3; j++) printf("%d\n",age[j]); getch(); } age[2]

6. Reading Data from User  for loop is used to read data from the user.

7. Arrays: Example #include<stdio.h> #include<conio.h> int main() { int age[3]; #include<stdio.h> #include<conio.h> int main() { int age[3]; for (int i = 0; i<3; i++) { printf("Enter ages \n"); scanf("%d",&age[i]);} printf("Ages are "); for (int j=0; j<3; j++) printf("%d \n",age[j]); age[0] = 25; age[1] = 30; age[2] = 35; printf("Ages are "); for (int j=0; j<3; j++) printf("%d\n",age[j]); getch(); } getch(); }

8. Initializing Arrays in Declarations • Possible to declare the size & initialize int results [5] = {14, 6, 23, 8, 12 } • Possible to omit size at declaration – Compiler figures out size of array float prices [ ] = { 2.41, 85.06, 19.95, 3.91 }

9. Arrays Initialization: Example #include<stdio.h> #include<conio.h> #include<stdio.h> #include<conio.h> int main() { int main() { Empty brackets can take size any int age[3] = {25, 30, 35}; int age[ ] = {25, 30, 35}; for (int j=0; j<3; j++) for (int j=0; j<3; j++) printf("%d\n",age[j]); getch(); } printf("%d\n",age[j]); getch(); }

10. Arrays: Class Exercise #include<stdio.h> #include<conio.h> int main() { int order[5]; printf("Enter numbers \n"); for(int i=0; i<=4; i++) scanf("%d ", &order[i]); for (int j=4; j>=0; j--) printf("%d\n", order[j]); getch(); } Write a C program using arrays accepts five integers and then prints them reverse order. that (05) in

11. Class work  WAP to read 10 numbers from the user and display them.  WAP to read 20 numbers from the user and find out the highest number.

12. Advantage of Array  Huge amount of data can be stored under single variable name.  Searching of data item is faster.  2 dimension arrays are used to represent the matrices.  It is helpful in implementing other data structure like linked list, queue,stack.

13. 2-Dimensional Arrays • A collection of a fixed number of components arranged in two dimensions – All components are of the same type • The syntax for declaring a two-dimensional array is: dataType arrayName[intexp1][intexp2]; where intexp1 and intexp2 are expressions yielding positive integer values; e.g., double sales[10][5]

14. 2-Dimensional Arrays • The two expressions intexp1 and intexp2 specify the number of rows and the number of columns, respectively, in the array • Two-dimensional matrices or tables arrays are sometimes called

15. 2-Dimensional Arrays double sales[10][5];

16. 2-Dimensional Arrays  The syntax to access a component of a two- dimensional array is: arrayName[indexexp1][indexexp2] where indexexp1 and indexexp2 are expressions yielding nonnegative integer values  indexexp1 specifies the row position and indexexp2 specifies the column position

17. 2-Dimensional Arrays sales[2][3] = 35.60; 35.60

18. 2-Dimensional Arrays Accessing Accessing all of the elements of a two-dimensional array requires two loops: one for the row, and one for the column. Since two-dimensional arrays are typically accessed row by row, generally the row index is used as the outer loop.   for (int nRow = 0; nRow < nNumRows; nRow++) for (int nCol = 0; nCol < nNumCols; nCol++) printf(“%d”,anArray[nRow][nCol]);

19. 2 DIM. Arrays: Example #include<stdio.h> #include<conio.h> //complete program by //printing the values which look like this: int main() { double sales[2][3]; sales[0][0] = 2.3; sales[0][1] = 3.5; sales[0][2] = 4.2; sales[1][0] = 5.6; sales[1][1] = 6.7; sales[1][2] = 7.8;

20. 2-Dimensional Arrays Initialization Like one-dimensional arrays  Two-dimensional arrays can be initialized when they are declared To initialize a two-dimensional array when it is declared Elements of each row are enclosed within braces and separated by commas All rows are enclosed within braces For number arrays, if all components of a row are not specified, the unspecified components are initialized to zero   1) 2) 3)

21. 2-Dimensional Arrays Initialization Example:  int anArray[3][5] = { { 1, 2, 3, 4, 5, }, { 6, 7, 8, 9, 10, }, { 11, 12, 13, 14, 15 } }; // row 0 // row 1 // row 2

22. 2 DIM. Arrays: Example #include<stdio.h> #include<conio.h> int main() { int matrix[2][2] = { for(int i = 0; i < 2; i++) { for(int j = 0; j < 2; j++) { printf(" %d", matrix[i][j]); } printf("\n"); } getch(); } {2,3,}, //row0 {5,7} //row1 }; printf("\n Resultant \n");

23. 2 DIM. Arrays: Class Exercise Write a C program using 2 DIM. arrays that gets 2x2 matrix input from the user and then prints the resultant matrix. The output should look like this:

24. 2 DIM. Arrays: Exercise Solution #include<stdio.h> #include<conio.h> int main() { int matrix[2][2]; { printf(" %d " ,matrix[i][j]); } printf("\n"); } getch(); } for(int i = 0; i < 2; i++) { for(int j = 0; j < 2; j++){ printf("Enter values for [%d %d] ",i,j); scanf("%d",& matrix[i][j]); printf("\n");}} printf("resultant:\n"); for(int i = 0; i < 2; i++) { for(int j = 0; j < 2; j++)

25. 2 DIM. Arrays: Class Exercise Write a C program using 2 DIM. arrays that gets matrices as an input from the user and then prints the sum of entered matrices. The output look like this: two 2x2 should

26. #include<conio.h> #include<stdio.h> int main() { int a[2][2],b[2][2],i,j; printf("\n1st MATRIX:\n\n"); for(i=0;i<2;i++){ for(j=0;j<2;j++) { scanf("%d",&a[i][j]); }} printf("\n2nd MATIX:\n\n"); for(i=0;i<2;i++) for(j=0;j<2;j++)                             scanf("%d",&b[i][j]); printf("\nresultant:\n"); for(i=0;i<2;i++){ for(j=0;j<2;j++) { printf("%d ",a[i][j]+b[i][j] ); } printf("\n"); } getch(); return 0; }

27. 2 DIM. Arrays: Assignment 1) Write a C program using arrays that produces the multiplication of two matrices.