Reading array int x[10]; for(i=0; i<=9; i++) {

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2 Examples: int a[10]; // declare int array of 10 elements float x[5]; int a=0, x[5]=0; int b[5]=7, 2, 3, 1, 6; // where b[0]=7, b[1]=2, b[2]=3, b[3]=1, b[4]=6 Reading array int x[10]; for(i=0; i<=9; i++) Cout<<"Enter number: "; Cin>>x[i];

3 //continue with reading array example Output>> Enter number: 5 Enter number: 3. Example for printing array: for(i=0; i<=9; i++) cout<<x[i]<<" ";.. If you want the output like: Enter x[0] Enter x[1] cout<<"enter x["<<i<<"]";

4 Example: write a C++ program that reads in an array of 10 integers and prints array and find the sum of array elements. #include <iostream> int main() int x[10], i, s=0; for(i=0; i<=9; i++) cout<<"enter a number"; cin>>x[i]; for(i=0; i<=9; i++) cout<<x[i]<<" "; cout<<"\n"<<"sum= "<<sum; return 0; sum+=x[i];

5 Example: write a program to read an array of 10 integer and find the maximum elements in the array. #include <iostream> int main() int x[10], i, max; for(i=0; i<=9; i++) cout<<"enter a number"; cin>>x[i]; max=x[0]; for(i=1; i<=9; i++) if(max<x[i]) max=x[i]; cout<<"max= "<<max; return 0;

6 a Example: same as above example find c= i=0 a i b i #include <iostream> int main() int x[10], b[10], c[10], i; for(i=0; i<=9; i++) cout<<"enter two numbers"; cin>>a[i]>>b[i]; c[i]+=a[i]*b[i]; for(i=0; i<=9; i++) cout<<c[i]<<" "; return 0;

7 Example: write a program to read array a[10] and find array b[10] such that elements of b are revers of a's elements.

8 Passing array to functions: - C++ automatically treated the using of arrays as parameter by using call by reference Example: void f(int[], int); //prototype int a[10]; f(a, 10); void f(int x[], int size) x[5]++;

9 Example: write a program that reads integer array a[10] by using a function and print this array by using another function. #include <iostream> void read_array(int [], int); void print_array(int [], int); int main() int a[10]; read_array(a, 10); print_array(a,10); return 0;

10 //continue with example void read_array(int x[], int size) int i; for(i=0; i<=size-1; i++) cout<<"enter number: "; void print_array(int x[], int size) int i for(i=0; i<=size-1; i++) cout<<x[i]<<"\t"; cin>>x[i];

11 Example: write a program to read two arrays and print two arrays. #include <iostream> void read_array(int [], int); void print_array(int [], int); int main() int a[10], b[5]; read_array(a, 10); print_array(a,10); read_array(b, 5); print_array(b, 5); return 0;

12 //continue with the example void read_array(int x[], int size) int i; for(i=0; i<=size-1; i++) cout<<"enter number: "; void print_array(int x[], int size) int i for(i=0; i<=size-1; i++) cout<<x[i]<<"\t"; cin>>x[i];

13 Example: write a program that reads two arrays a[10], b[10] and print these array then find and print the sum array. Use 3 functions for reading, finding sum and printing.

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15 Example: write a program that reads array of 10 integers and print this array then sort the elements of array ascending and print this array again. Use function for reading, function for printing and function for sorting. #include <iostream> void read_array(int [], int); void print_array(int [], int); void sort(int [], int); int main() int a[10]; read_array(a, 10); print_array(a,10); sort(a, 10); print_array(a, 10); return 0; void read_array(int x[], int size) int i; for(i=0; i<=size-1; i++) cout<<"enter number: "; cin>>x[i];

16 //continue with the example void print_array(int x[], int size) int i for(i=0; i<=size-1; i++) cout<<x[i]<<"\t"; z=x[i]; x[i]=x[i+1]; x[i+1]=z; void sort(int x[], int size) int p, i, z; for(p=1; p<=size-1; p++) for(i=0; i<=size-1; i++) if(x[i]>x[i+1])

17 Example: modify the above sort function by using a function for swapping. #include <iostream> void read_array(int [], int); print_array(a, 10); return 0; void print_array(int [], int); void sort(int [], int); void swap(int &, int&); int main() int a[10]; read_array(a, 10); print_array(a,10); sort(a, 10); void read_array(int x[], int size) int i; for(i=0; i<=size-1; i++) cout<<"enter number: "; cin>>x[i];

18 //continue with the example void print_array(int x[], int size) int i for(i=0; i<=size-1; i++) cout<<x[i]<<"\t"; void sort(int x[], int size) int p, i, z; for(p=1; p<=size-1; p++) for(i=0; i<=size-1; i++) if(x[i]>x[i+1]) swap(x[i], x[i+1]); void swap(int &x, int&y) int x; m=x; x=y; y=m;

19 Homework: write a program that use a function for reading array of 10 integers and use another function for search in the array.

20 3. Two Dimensional arrays (matrix) Declaration: we need number of columns and number of rows. Example: int a[3][4];>> integer array a with 3 rows and 4 columns. column 0 column 1 column 2 column 3 row 0 a[0][0] a[0][1] a[0][2] a[0][3] row 1 a[1][0] a[1][1] a[1][2] a[1][3] row 2 a[3][0] a[3][1] a[3][2] a[3][3] - Initialization: int a[2][3]=1, 2, 3, 4, 5, 6; row 0: OR int a[2][3]=1, 2, 3, 4, 5; row 1: 4 5 6

21 Example: write C++ program that reads integer array a[3][4] and then print it. #include <iostream> int main() int a[3][4], i, j; for(i=0; i<=2; i++) for(j=0; j<=3; j++) cout<<"enter a number: "; cin>>a[i][j]; for(i=0; i<=2; i++) return 0; for(j=0; j<=3; j++) cout<<a[i][j]<<" "; cout<<"\n";

22 Example: write C++ program that reads integer array a[3][4] and find the maximum elements. #include <iostream> int main() int a[3][4], i, j, max, row, col; for(i=0; i<=2; i++) for(j=0; j<=3; j++) max=a[0][0]; cout<<"enter a number: "; cin>>a[i][j]; for(i=0; i<=2; i++) for(j=0; j<=3; j++) if(max<a[i][j]) max=a[i][j]; row=i; col=j; cout<<"the maximum= "<<max; return 0;

23 Example: write C++ program that reads two arrays a[4][4] and b[4][4] and finds c=a+b. #include <iostream> int main() int a[4][4], b[4][4], i, j; for(i=0; i<=3; i++) for(j=0; j<=3; j++) cout<<"enter two numbers: "; cin>>a[i][j]>>b[i][j]; c[i][j]=a[i][j]+b[i][j]; for(i=0; i<=3; i++) for(j=0; j<=3; j++) cout<<c[i][j]<<"\t"; return 0;

24 Homework: write C++ program for each of the following after reading a[4][4]. 1. Sum of the array elements. 2. Sum of upper triangle. 3. Sum of out border elements. 4. B = A T Homework: write C++ program that reads a[4][4] and b[4][4] 3 and finds c=a*b. where c ij = k=0 a ik b kj.