Arrays in C. By Mrs. Manisha Kuveskar.

Transcription

1 Arrays in C By Mrs. Manisha Kuveskar.

2 C Programming Arrays An array is a collection of data that holds fixed number of values of same type. For example: if you want to store marks of 100 students, you can create an array for it. float marks[100]; The size and type of arrays cannot be changed after its declaration.

3 C Programming Arrays Arrays are of two types: One-dimensional arrays Multidemensional arrays

4 How to declare an array in C? data_type array_name[array_size]; For example, float mark[5]; Here, we declared an array, mark, of floating-point type and size 5. Meaning, it can hold 5 floating-point values.

5 C Programming Arrays How to declare an array in C?

6 Elements of an Array and How to access them? You can access elements of an array by indices. Suppose you declared an array mark as above. The first element is mark[0], second element is mark[1] and so on.

7 Few key notes: Arrays have 0 as the first index not 1. In this example, mark[0] If the size of an array is n, to access the last element, (n-1) index is used. In this example, mark[4] Suppose the starting address of mark[0] is 2120d. Then, the next address, a[1], will be 2124d, address of a[2] will be 2128d and so on. It's because the size of a float is 4 bytes.

8 How to initialize an array in C programming? It's possible to initialize an array during declaration. For example, int mark[5] = {19, 10, 8, 17, 9;Another method to initialize array during declaration: int mark[] = {19, 10, 8, 17, 9;

9 1-D ARRAY Here, mark[0] is equal to 19 mark[1] is equal to 10 mark[2] is equal to 8 mark[3] is equal to 17 mark[4] is equal to 9

10 /* write a prog to declare, modify and print elements of a given array*/ #include<stdio.h> #include<conio.h> void main() { int demo[10]; int i; clrscr(); /* Enter array elements */ for(i=0;i<10;i++) { printf(" Enter elements of array:"); scanf("%d",&demo[i]); printf("\n Display array element."); for(i=0;i<10; i++) { demo[i]= demo[i]+1; printf("\n%d",demo[i]); getch();

11 To find maximum of array elements

12 #include<stdio.h> #include<conio. h> void main() { int num[10]={34,6,23,56,34,78,67,23,12,90; int i,max; max=num[0]; /* logic to findout maximum no */ for(i=1;i<=9;i++) { if(num[i] >max) max=num[i]; printf("\maximum element of array is %d", max); getch();

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14 /* write a prog to arrenge elements of array in ascendig order &to print elements array*/ #include<stdio.h> #include<conio.h> void main() { int demo[10]; int i,temp,j; clrscr();

15 /* read array elements */ for(i=0;i<10;i++) { printf(" Enter % element of array:",i+1); scanf("%d",&demo[i]); /*Display array elements */ printf("\n Display array element."); for(i=0;i<10;i++) { Printf( %d\t, demo[i][j]);

16 { for(j=i;j<10;j++) { if(demo[i]> demo[j]) { temp= demo[i]; demo[i]= demo[j]; demo[j]=temp;

17 printf("\n Elements of array in ascending order are as follows:"); for(i=0;i<10;i++) { printf("\n%d",demo[i]); getch(); #in

18 C Programming Multidimensional Arrays

19 2-D ARRAY In C programming, you can create an array of arrays known as multidimensional array. For example, float x[3][4]; Here, x is a two-dimensional (2d) array. The array can hold 12 elements. You can think the array as table with 3 row and each row has 4 column.

20 2-D ARRAY

21 How to initialize a multidimensional array? There is more than one way to initialize a multidimensional array. Initialization of a two dimensional array // Different ways to initialize two dimensional array int c[2][3] = {{1, 3, 0, {-1, 5, 9; int c[ ][3] = {{1, 3, 0, {-1, 5, 9; int c[2][3] = {1, 3, 0, -1, 5, 9;

22 Matrix Multiplication Dimension of Matrix 1 : 1 X 3 Dimension of Matrix 2 : 3 X 2

23 Matrix Multiplication Multiplication is Possible if--- No. of Columns of Matrix 1 = No of Columns of Matrix 2 Resultant Matrix Will of Dimension- C[No. of Rows of Mat1][No. of Columns of Mat2]

24 Matrix Multiplication Multiplication is Possible if--- No. of Columns of Matrix 1 = No of Columns of Matrix 2 Resultant Matrix Will of Dimension- C[No. of Rows of Mat1][No. of Columns of Mat2]

25 Matrix Multiplication Evaluate : 1 X 2 = 2 Evaluate : 4 X 5 = 20 Evaluate : 6 X 7 = Add : 64 ///c[0][0] Evaluate : 1 X 3 = 3 Evaluate : 4 X 8 = 40 Evaluate : 6 X 9 = Add : 89 ///c[0][1]

26 /* matrix multiplication */ #include<stdio.h> #include<conio.h> #include<math.h> void main() { int a[10][10],b[10][10],c[10][10],i,j,k; /*int sum=0; */ clrscr();

27 Read elemets of first matrix printf("\n Enter elemnts of first matrix: \n"); for(i=0;i<3;i++) { for(j=0;j<3;j++) scanf("%d", &a[i][j]);

28 Read elemets of second matrix printf("\n Enter elemnts of first matrix: \n"); for(i=0;i<3;i++) { for(j=0;j<3;j++) scanf("%d", &b[i][j]);

29 Display first matrix /* Display first matrix*/ printf("\n the first matrix is :\n "); for(i=0;i<3;i++) { for(j=0;j<3;j++) printf("%d\t", a[i][j]); printf("\n");

30 Display Second matrix /* Display first matrix*/ printf("\n the first matrix is :\n "); for(i=0;i<3;i++) { for(j=0;j<3;j++) printf("%d\t", b[i][j]); printf("\n");

31 Multiplication Logic c[i][j]=0; /* mul is initialised to zero */ for(i=0;i<3;i++) /* row */ { for(j=0;j<3;j++) /* column */ { c[i][j]=0; for(k=0;k<3;k++) /* row- col wise multiplication*/ { c[i][j]=c[i][j]+a[i][j]*b[k][j]; /* i=0, j=0, k=0,1,2 */

32 Multiplication Logic for (i = 0; i <= 2; i++) /* rows of matrix */ { for (j = 0; j <= 2; j++) /* column of matrix */ { sum = 0; for (k = 0; k <= 2; k++) /*row wise-column elemnt*/ { /* ie: j=0; row=0,1,2 */ sum = sum + a[i][k] * b[k][j]; c[i][j] = sum;

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39 Initialization of a three dimensional array. You can initialize a three dimensional array in a similar way like a two dimensional array. Here's an example, int test[2][3][4] = { { {3, 4, 2, 3, {0, -3, 9, 11, {23, 12, 23, 2, { {13, 4, 56, 3, {5, 9, 3, 5, {3, 1, 4, 9 ;