Array Initialization and Display: One-Dimensional and Two-Dimensional Arrays - Part I

1. Arrays One-Dimensional initialize & display Arrays as Arguments Two-dimensional initialize & display Part I

2. char, int, float, double array, struct, union, class Data Types • simple or atomic • structured * *

3. Structured Data Type - Array • An array is a collection of data storage locations, each of which holds the same type of data. Each storage location is called an element of the array. • Each element is referred to as an indexed or subscripted variable.

4. Array Declaration • Syntax dataType arrayName [ ConstIntExpression ] • The number of elements in an array is • stated within square brackets, [ ]. • Examples double angle [4]; constant POLY = 8; int testScore [12]; double angle [POLY]; char password [8];

5. Array Storage • Each array has sufficient memory reserved to hold the number of data items of the given type. • Initializing an array sets up the address of the first element. Addresses of all other elements are offsets from the starting address.

6. Array Element Access • Syntax • arrayName [ indexExpression ] • Program access to each of the array elements is by referring to an offset from the array name. Array elements are counted beginning with zero.

7. Array Element Access • double angle[4]; // declaration • Example angle [0] = 6.21; angle [1] = 15.89; angle [2] = 7.5; angle [3] = -45.7; angle sub zero = 6.21angle sub one = 15.89angle sub two = 7.5angle sub three = -45.7 * * *

8. Using Array Elements • write the contents of an array element: cout << angle[2]; • assign values to an array element: cin >> angle[3]; angle[6] = pow(axis,4); • use it as a parameter: y = sqrt(angle[0]); • use it in an expression: x = 2.5 * angle[1] + 64; * * * *

9. Array Component Access • for(index=0; index < arraySize; index++) myArray[index] = 0.0; Zero out an entire array. (Initialize every element to 0.0.) 100 * *

10. [ 0 ] [ 1 ] [ 2 ] [ 3] @#$ @#$ Off Set • memoryaddresses • starting address • off set by one unit • off set by two units • off set by three units

11. [ 0 ] [ 1 ] [ 2 ] [ 3] @#$ @#$ Out-of-Bounds Array Index • memoryaddresses • angle[4] = 135; cout << angle[5];

12. Declare an Array • Syntax type arrayName[index]; Example double dailyHigh[23] ; int quizGrade[132] ; char ASURiteID[5] ; *

13. Initialize an Array Element • Syntax arrayName[index] = value; Example dailyHigh[18] = 16.7; quizGrade[2] = 15; ASURiteID[3] = ‘d’; *

14. Initialize an Array double angle[4] = {16.21, 15.89, 7.5, -45.7}; double ATtoCG[5] = {.64, .89, .76, .83, .65}; int scores[12] = {210, 198, 203, 188, 200, 224, 220, 217, 211, 194, 197, 189}; double iona[8] = {0.0}; *

15. int scores[ ] = {210, 198, 203, 188, 200, 224, 220, 217, 211, 194, 197, 189}; Initialize an Array char name[4] = {‘Z’, ‘o’, ‘l’, ‘a’}; char name[4] = “Zola”; // no braces or , char phrase [ ] = “Hello World”; * *

16. Initialize an Array double angle[4]; // declaration Example angle [0] = 6.21; angle [1] = 15.89; angle [2] = 7.5; angle [3] = -45.7; angle sub zero = 6.21angle sub one = 15.89angle sub two = 7.5angle sub three = -45.7 *

17. Sequencing Through an Array • Use the for statement to sequence through an array. • Total the contents of an array: sum = 0; for(index=0; index < 7; index++) sum = sum + grades[index];

18. Loading an Array • double grade[10]; • int index; • for(index=0; index < 10; index++){ cout<<“Enter a grade “; • cin >> grade[index]; • }

19. Finding the Max/Min Value • Set the max or min to element zero. • Use a for loop to cycle through the array. • Compare each element to the max/min. • If necessary, assign a new value to max/min. How would you do this? *

20. Finding the Maximum Value • double find_max(int temp[30]) • { • max = temp[0]; • for(index=0; index < 30; index++) if (temp[index] > max) max = temp[index]; • return (max); • } *

21. Finding the Minimum Value • double find_min(int temp[30]) • { • min = temp[0]; • for(index = 1; index < 30; index++) if (temp[index] <min) min = temp[index]; • return ( min ); • } *

22. Aggregate Assignment - NOT! • There are no aggregate assignments with arrays. That is, you may not assign one array to another. • int x[5] = {11, 22, 33, 44, 55}; • int y[5]; • y = x; y[ ] = x[ ];

23. Arrays as Arguments • void find_max(int temp[ ]) • { • max = temp[0]; • for(index = 1; index < 30; index++) if (temp[index] > max) max = temp[index]; • } double find_max(int temp[ ]) return max; *

24. Passing an Array/Element • find_max(temp); // no [ ] • inventory(price, quantity, amount); // 3 arrays • words(cuplet); • find_max(temp[3]); • inventory(price, quantity[4], amount[12]); • words(cuplet); *

25. Passing an Array • formal parameter formal parameter declaration for declaration forparameterPass-by-Value Pass-by-Reference • simple var. int cost int& pricearray impossible int myArray[ ] • array const int source[ ]

26. 1-D Array Review • An array is a structured data type • 1st element is “arrayName subzero” • Array Declaration int myArray [9]; • Array Initialization int myArray [9 ] = { 9, 9, 9, 8, 7, 6, 5, 4, 3}; • Array Element Reference myArray [7]; // value = 4 9 *

27. optional 1-D Array Review • Arrays are always passed by reference, unless const added to the formal parameter. • Array in a Function Prototype • void myFunction(int [9]); • Array in a Function Call myFunction(myArray); • Array in a Function Header void myFunction(int anyArrayName[9])

28. Two Dimensional Arrays • everything about one dimensional arrays applies • sometimes referred to as a table • has rows and columns ex. multiplication table

29. 2-D Array Declaration • Syntax • dataType arrayName [ ConstIntExpression ][ ConstIntExpression ]l l l • Example • int highTemp [52] [7]; double matrix [8] [8]; // checker board int roomSchedule [237] [13];

30. 2-D Array Initialization • int nums [3] [2] = {7, 4, 1, 8, 5, 2} • int roomsPSF[3] [7] = { {17, 18,19, 110, 111, 112, 113}, {27, 28, 29, 210, 211,212, 213}, {37, 38, 39, 310, 311, 312, 313} };

31. 2-D Array Initialization • double ATtoCG[2] [3] = {.74, .79, .76, .83, .65, .89}; • double ATtoCG[2] [3] = { {.74, .79, .76}, {.83, .65, .89} }; • int scores[4] [3] = {210, 198, 203, 188, 200, 224, 220, 217, 211, 194, 197, 189};

32. 2-D Array Initialization • You can assign values to individual elements: • ATtoGC [0] [0] = 0.74; ATtoGC [0] [1] = 0.79; ATtoGC [0] [2] = 0.76; ATtoGC [1] [0] = 0.83; ATtoGC [1] [1] = 0.65; ATtoCG [1] [2] = 0.89; *

33. Accessing a 2-D Array • very similar to creating a multiplication table. • use nested loops. outer for loop was for the rows inner for loop was for the columns

34. Loading a 2-D Array • The Multiplication Table • for (row =1; row <=10; row++) • { • cout <<setw(5)<<row<<" "; • for (column=1; column <= 10; column++) • cout << setw(5)<< column*row; • cout << endl; • }

35. Loading a 2-D Array • int scores [4][3]; • for(row=0; row<4; row++) • for(col=0; col<3; col++) • { • cout<<"Enter the value :"; • cin>>scores[row][col]; • }

36. Loading a 2-D Array • scores [0][0] [2][0] [0][1] [2][1] [0][2] [2][2] • [1][0] [3][0] [1][1] [3][1] [1][2] [3][2] [row][col] = somevalue;

37. Displaying a 2-D Array • int scores [4] [3]; • for(row=0; row<4; row++) • { • for(col=0; col<3; col++) • cout << setw(6) << scores[row][col]; • cout << endl; // new line for each row • }

38. Displaying a 2-D Array • Output • 210 198 203 188 200 224 220 217 211 194 197 189

39. Functions and 2-D Arrays • int test[7][19]; // declaration • find_min(test); // function call • int find_min(int num [7][19]) // funct. header char code[26][10]; obtain(code); char obtain(char key [26][10]) * * * *

40. Local vs. Global • No difference

41. “One might as well say he has sold when no one has bought as to say he has taught when no one has learned.” John Dewey