1. CS 1430: Programming in C++

2. Arrays float Scores[9]; // one dimensional array
index:
55.5
59.0
47.0
39.0
50.5
60.0
40.0 ?
element

3. Two Dimensional Arrays
float allScores[5][9];
column index
row index 1 2 3 4

4. Accessing Array Elements
float allScores[5][9];
allScores[0][0]
allScores[0][8]
column index
row index
3.5
3.9
3.2
3.0 1 2 3 4
allScores[2][5]
allScores[4][8]

5. Accessing Array Elements
float allScores[5][9];
// Each array element is
// the same as a variable
cin >> allScores[0][0];
allScores[0][0] += 5.0;
cout << allScores[0][0];

6. For Loop and 2-D Arrays float allScores[5][9];
// Input values to 1st row
// Row index of 1st row: 0
// Column index: 0 to 8 (size – 1)
for (int col = 0; col < 9; col ++)
cin >> allScores[0][col];
// inFile >> allScores[0][col];

7. For Loop and 2-D Arrays const int MAX_ROWS = 10;
const int MAX_COLS = 35;
float allScores[MAX_ROWS][MAX_COLS];
// Input values to the last column
// Column index of last column: 34 (MAX_COLS – 1)
// Row index: from 0 to 9 (MAX_ROWS – 1)
for (int row = 0; row < MAX_ROWS; row ++)
cin >> allScores[row][MAX_COLS - 1];
// inFile >> allScores[row][MAX_COLS - 1];

8. For Loop and 2-D Arrays const int MAX_ROWS = 10;
const int MAX_COLS = 35;
float allScores[MAX_ROWS][MAX_COLS];
// Input values to the entire 2-D array
for (int row = 0; row < MAX_ROWS; row ++)
for (int col = 0; col < MAX_COLS; col ++)
cin >> allScores[row][col];
// inFile >> allScores[row][col];

9. For Loop and 2-D Arrays const int MAX_ROWS = 10;
const int MAX_COLS = 35;
float allScores[MAX_ROWS][MAX_COLS];
int numRows, numCols;
cout << “Enter No. of rows and No. of cols: ”;
cin >> numRows >> numCols;
// numRows <= MAX_ROWS
// numCols <= MAX_COLS
for (int row = 0; row < numRows; row ++)
for (int col = 0; col < numCols; col ++)
cin >> allScores[row][col];

10. Two Dimensional Arrays as Function Parameters//
// The function inputs values to all array
// elements within the first numRows rows and
// the first numCols columns.
// Parameters: (Out, In, In)
void GetData(float a[][MAX_COLS], int numRows, int numCols) {
for (int row = 0; row < numRows; row ++)
for (int col = 0; col < numCols; col ++)
cin >> a[row][col];
return; }
// Have to specify MAX_COLS!
// float a[][MAX_COLS]

11. Two Dimensional Arrays as Function Parameters//
// The function inputs values for numRows and numCols,
// then inputs values to all array elements within
// the first numRows rows and the first numCols
// columns.
// Parameters: (Out, Out, Out)
void GetAllData(float a[][MAX_COLS], int& numRows,int& numCols) {
cin >> numRows >> numCols;
for (int row = 0; row < numRows; row ++)
for (int col = 0; col < numCols; col ++)
cin >> a[row][col];
return; }

12. Two Dimensional Arrays as Function Parameters//
// The function has 3 parameters:
// a[][MAX_COLS]: 2-D array of float
// colIndex, numRows: int
// The function computes and returns the average
// value of the column at index colIndex.
// Params: ( ? , ? , ? )
float columnAvg( ) { }

13. Two Dimensional Arrays
float columnAvg( );
colIndex
numRows - 1

14. Two Dimensional Arrays as Function Parameters//
// The function has 3 parameters:
// a[][MAX_COLS]: 2-D array of float
// colIndex, numRows: int
// The function computes and returns the average
// value of the column at index colIndex.
// Params: ( In , In , In )
float columnAvg(const float a[][MAX_COLS],
int colIndex, int numRows) {
float total = 0;
for (int row = 0; row < numRows; row ++)
total += a[row][colIndex];
return (total / numRows); }

15. Two Dimensional Arrays as Function Parameters//
// The function has 3 parameters:
// a[][MAX_COLS]: 2-D array of float
// numCols, rowIndex: int
// The function finds and returns the column index
// of row at index rowIndex that has the max
// value among all elements of row rowIndex.
// Params: ( ? , ? , ? )
int IndexOfRowMax( ) { }

16. Two Dimensional Arrays
int IndexOfRowMax();
numCols - 1
rowIndex

17. Two Dimensional Arrays as Function Parameters//
// The function has 3 parameters:
// a[][MAX_COLS]: 2-D array of float
// numCols, rowIndex: int
// The function finds and returns the column index
// of row at index rowIndex that has the max
// value among all elements of the row.
// Params: ( In , In , In )
int IndexOfRowMax(const float a[][MAX_COLS],
int rowIndex, int numCols) {
int index = 0;
for (int col = 1; col < numCols; col ++)
if (a[rowIndex][col] > a[rowIndex][index])
index = col;
return index; }

18. Function Prototypes void GetData(float a[][MAX_COLS], int numRows,
int numCols);
void GetAllData(float a[][COL_SIZE],
int& numRows, int& numCols);
float columnAvg(const float a[][MAX_COLS],
int colIndex, int numRows);
int IndexOfRowMax(const float a[][MAX_COLS],
int rowIndex, int numCols);
// Must specify column MAX_SIZE!

19. Two Dimensional Arrays as Function Parameters
const int MAX_ROWS = 10;
const int MAX_COLS = 35;
int main() {
float allScores[MAX_ROWS][MAX_COLS];
int rows, cols;
// Input sizes in main() function.
cin >> rows >> cols;
// Call function GetData().
GetData(allScores, rows, cols);
// No [] for allScores
...
return; }

20. Call Functions int main() { float allScores[MAX_COLS][MAX_ROWS];
int rows, cols, row, col, index;
float average;
GetAllData(allScores, rows, cols);
cout << "Enter column index: ";
cin >> col;
average = columnAvg(allScores, col, rows);
cout << "The average value of column " << col
<< " is " << average;
cout << "Enter row index: ";
cin >> row;
index = IndexOfRowMax(allScores, row, cols);
cout << "The largest value of row " << row << " is "
<< allScores[row][index];
// << allScores[row][IndexOfColMax(allScores, row, cols)];
return 0; }

21. Function Prototypes and Function Calls
void GetAllData(float a[][COL_SIZE],
int& numRows, int& numCols);
float columnAvg(const float a[][MAX_COLS],
int colIndex, int numRows);
int IndexOfRowMax(const float a[][MAX_COLS],
int rowIndex, int numCols);
// Function calls
GetAllData(allScores, rows, cols);
average = columnAvg(allScores, col, rows);
index = IndexOfRowMax(allScores, row, cols);

22. Schedule
Quiz9-3 (1 bonus point) Name your cpp file as UserName-Quiz9-3.cpp (YangQ-Quiz9-3.cpp) Drop it to K:\Courses\CSSE\yangq\CS1430-Dropbox\Quiz9-3 Lab 11 5 pm Thursday Prog 6 Due Tuesday, Dec 8

23. Test 3 Wednesday, Dec 9 Quiz3 Now
Schedule
Test 3 Wednesday, Dec 9 Quiz3 Now