Arrays in CPP

Arrays in CPP

• 1.
  Object Oriented Programming Arrays
• 2.
  Introducing Arrays Array isa data structure that represents a collection of the same types of data. arr [0] arr [1] arr [2] arr [3] arr [4] arr [5] arr [6] arr [7] arr [8] arr [9] int arr[ 10]; arr reference An array of 10 elements of type int Array position starts from 0
• 3.
  Declaring Array Variables Datatype arrayname[arraysize]; Example: int numbers[10];  datatype arrayname[arraysize]={arrayvalue}; Example: int numbers[5]={2,3,4,5,6}; Once an array is created, its size is fixed. It cannot be changed. You can find its size using
• 4.
  Initializing Arrays  Usinga loop: for (int i = 0; i < 4; i++) myList[i] = i;  Declaring & initializing in one step: double myList[] = {1.9, 2.9, 3.4, 3.5};
• 5.
  Declaring & initializingin one step double myList[] = {1.9, 2.9, 3.4, 3.5}; This shorthand notation is equivalent to the following statements: double myList[4]; myList[0] = 1.9; myList[1] = 2.9; myList[2] = 3.4; myList[3] = 3.5;
• 6.
  Example 1 Write apogram that read and display an array int main() { int a[5], i; for(i=0;i<5;i++) { cin>>a[i]; } for(i=0;i<5;i++) { cout<<a[i]; } return 0; }
• 7.
  Example 2 Find thelargest of 10 numbers using array. void main() { int i, a[20],max=0; for (i=1; i< 10; i++) { cout<<“enter number n”; cin>>a[i]; If (a[i] > max) max = a[i]; } cout<<max; }
• 8.
  Example 3 Write apogram that reads some values and display average void main() { int i, a[20],sum=0,avg; for (i=1; i< 10; i++) { cout<<“enter number n”; cin>>a[i]; sum=sum+a[i]; } avg=sum/10; cout<<“average is”<<avg; }
• 9.
  Example 4 Write aprogram that searches any number from an array int main() { int i,n,a[100],num,found; cout<<“How many numbers: "; cin>>n; for(i=0; i<n; i++){ cin>>a[i]; } cout<<“Enter any number to search: "; cin>>num;
• 10.
  Example 4 for(i=0; i<n;i++) { if(a[i]==num) { cout<<“Found."; break; } } if(i==n) cout<<“Not found.”; return 0; }
• 11.
  Copying Arrays A simpleassignment cannot copy arrays. Rather simply creates two arrays and attempts to copy one to the other, using an assignment statement. int list1[] = {2, 3, 1, 5, 10}; int list2[] = {1, 5, 7, 8, 9}; for (int i = 0; i < 5; i++) list2[i] = list1[i];
• 12.
  Copying Arrays Contents of list1 list1 Contents oflist2 list2 Before the assignment list2 = list1; Contents of list1 list1 Contents of list2 list2 After the assignment list2 = list1; Garbage
• 13.
  Multidimensional Arrays Declaring Variablesof Multidimensional Arrays and Creating Multidimensional Arrays int array[5][4]; or int array[][4]; Assigning value at[0][2]position: array[0][2] = 3; for (i=0; i<5; i++) for (j=0; j<4; j++) { array[i][j] = rand()*1000; } double[][] x;
• 14.
  Multidimensional Array Illustration 01 2 3 4 0 7 0 1 2 3 4 1 2 3 4 0 1 2 3 4 int arr[2][1] = 7;int arr[5][5]; 3 7 0 1 2 0 1 2 int arr[][] = { {1, 2, 3}, {4, 5, 6}, {7, 8, 9}, {10, 11, 12} }; 1 2 3 4 5 6 8 9 10 11 12
• 15.
  Declaring, Creating, andInitializing You can also use a shorthand notation to declare, create and initialize a two-dimensional array. For example, int array[][] = { {1, 2, 3}, {4, 5, 6}, {7, 8, 9}, {10, 11, 12} }; This is equivalent to the following statements: int array[4][3]; array[0][0] = 1; array[0][1] = 2; array[0][2] = 3; array[1][0] = 4; array[1][1] = 5; array[1][2] = 6; array[2][0] = 7; array[2][1] = 8; array[2][2] = 9; array[3][0] = 10; array[3][1] = 11; array[3][2] = 12;
• 16.
  Ragged Arrays Each rowin a two-dimensional array is itself an array. So, the rows can have different lengths. Such an array is known as a ragged array. For example, int matrix[][] = { {1, 2, 3, 4, 5}, {2, 3, 4, 5}, {3, 4, 5}, {4, 5}, {5} };
• 17.
  Example 6 Write aprogram to print a matrix. int main() { int i,j,a[10][10]; for(i=0;i<3;i++){ for(j=0;j<2;j++){ cin>>a[i][j]; } }
• 18.
  Example 6 for(i=0;i<3;i++){ for(j=0;j<2;j++){ cout<<a[i][j]; } cout<<“n”; } return 0; }