Multi-dimensional Arrays
2-D arrays
Allow you to store a table of data
Example:
float examGrades[3]; //1 dimensional array - lets you store 3 grades for one student
//To store several grades for many students using one identifier – use a 2D array
const int MAX_PEOPLE = 10;
const int NUM_GRADES = 3;
float examGrades[MAX_PEOPLE][NUM_GRADES]; //list row first, col second
//How to use it – requires 2 loops to read data into individual array cells
for (i =0; i < MAX_PEOPLE; i++) {
for (j = 0; j < NUM_GRADES; j++) {
cin >> examGrade[i][j];
}
}
When passed as a parameter, you don’t specify the first array size, but you need to specify the second
(or others if there are more.)
why?
C++ stores in row order in memory: first row…. second row…..third row …..
To reference an element you need to know where each row begins
Ex: //prototype
void readData(int [][NUM_GRADES], int);
//function heading
void readData(int grades[][NUM_GRADES], int number) { … }
