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Tutorial 7

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  1. Tutorial 7 Shruti Rathee Concordia University

  2. Arrays • An array is a group of items that can be identified as similar because they are of the same nature. • Arrays come in two flavors: one dimensional and multi-dimensional arrays.

  3. On dimensional array • Declaration : DataTypeArrayName[order] • Int num[5]; • Float mark[10]; • Double angle[360];

  4. Initialization • DataTypeArrayName[dimension] = { element1, element2, …, elementn}; • intnumber[2] = {18, 12,}; • double distance[5] = {44.14, 720.52, 96.08, 468.78, 6.28};

  5. Access an array • #include <iostream> using namespace std; intmain() { intarr[] = {4, 7, 9, 4, 6}; cout << ”array 1: " << array [0] << endl; cout << "array2: " << array [1] << endl; cout << "array3: " << array [2] << endl; cout << "array4: " << array [3] << endl; cout << "arrayDistance5: " <array [4] << endl; return 0; }

  6. Excercise • Take input from user for an array of length 10 and find the sum of all elelments in that array. • Declare an array like numbers[] = {8, 25, 36, 44, 52, 60, 75, 89} and then ask the user to input a number using cin and check whether it is in array.

  7. Solution 1. #include <iostream> using namespace std; int main() { // We know that we need a constant number of elements constint max = 10; int number[max]; // We will calculate their sum int sum = 0; cout << "Please type 10 integers.\n”; for( int i = 0; i < max; i++ ) { cout << "Number " << i + 1 << ": "; cin >> number[i]; sum += number[i]; } cout << "\n\nThe sum of these numbers is " << Sum << "\n\n"; return 0; }

  8. Solution 2 #include <iostream> using namespace std; int main() { // Declare the members of the array int numbers[] = {8, 25, 36, 44, 52, 60, 75, 89}; int find; int i, m = 8; cout << "Enter a number to search: "; cin >> find; for (i = 0; (i < m) && (Numbers[i] != Find); ++i) continue; / Find whether the number typed is a member of the array if (i == m) cout << find << " is not in the list" << endl; else cout << find << " is the " << i + 1 << "th element in the list" << endl; return 0; }

  9. Multidimensional array • An array of arrays is called a multidimensional array. • intanArray[3][5]; // a 3-element array of 5-element arrays • [0][0] [0][1] [0][2] [0][3] [0][4] [1][0] [1][1] [1][2] [1][3] [1][4] [2][0] [2][1] [2][2] [2][3] [2][4]

  10. Initialize • int anArray[3][2] = { { 1, 2 }, // row 0 { 6, 7 }, // row 1 { 11, 12 } // row 2 };

  11. Excercise • Write a program that calculates and prints a multiplication table for all values between 1 and 9 using two dimensional array. • Write a program to find the smallest number of the elements of an array

  12. Solution 3 // Declare a 10x10 array constintnNumRows = 10; constintnNumCols = 10; intnProduct[nNumRows ][nNumCols ] = { 0 }; // Calculate a multiplication table for (intnRow = 0; nRow < nNumRows; nRow++) for (intnCol = 0; nCol < nNumCols; nCol++) nProduct[nRow][nCol] = nRow * nCol; // Print the table for (intnRow = 1; nRow < nNumRows; nRow++) { for (intnCol = 1; nCol < nNumCols; nCol++) cout << nProduct[nRow][nCol] << "\t"; cout << endl; }

  13. Solution 4 #include <iostream> using namespace std; int main() { // The members of the array int numbers[] = {8, 25, 36, 44, 52, 60, 75, 89}; int minimum = numbers[0]; int a = 8; // Compare the members for (int i = 1; i < a; ++i) { if (numbers[i] < minimum) minimum = numbers[i]; } // Announce the result cout << "The lowestmembervalue of the array is " << minimum << "." << endl; return 0; }

  14. For more info • http://www.learncpp.com/cpp-tutorial/65-multidimensional-arrays/ • http://www.functionx.com/cpp/Lesson12.htm