1. COMP102 Lab 091 COMP 102 Programming Fundamentals I Presented by : Timture Choi

2. COMP102 Lab 092 2-D Array E.g. // declare a 2-D array of 30 uninitialized integers int table[3][10];  3 rows  10 columns -- 4 5 6 3 0 2 8 9 7 1 0 2 1

3. COMP102 Lab 093 2-D Array Accessing 2-D array Syntax array[row][column] E.g. table[1][2] = 5; x = table[1][2]; -- table 4 5 3 0 2 1 -- 5 0 2 1

4. COMP102 Lab 094 2-D Array Initialization Two methods to initialize a 2-D array int table[3][6] = {1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16, 17,18}; int table[3][6] = {{1,2,3,4,5,6}, {7,8,9,10,11,12}, {13,14,15,16,17,18}}; 14151613 table 4 5 3 0 2 1 1817 891071211 234165 0 2 1

5. COMP102 Lab 095 2-D Array Inputting Values Use two for loops to access/process all the elements of a 2-D array E.g. int total_row = 3, total_col = 6; for (int row=0; row<total_row; row++) for (int col = 0; col<total_col; col++) { // assign value to an element of array table[row][col] = row*col; … // assign value of an element to a variable temp = table[row][col]; }

6. COMP102 Lab 096 Mathematical Functions #include double log(double x)  Natural logarithm double log10(double x)  Base 10 logarithm double exp(double x)  e to the power x double pow(double x, double y)  x to the power y double sqrt(double x)  Square root of x double sin(double x) double cos(double x) double tan(double x)  In radian argument

7. COMP102 Lab 097 Mathematical Functions double ceil(double x) Smallest integer not less than x E.g.  ceil(1.1) => 2  ceil(-1.9) => -1 double floor(double x) Largest integer not greater than x E.g.  floor(1.9) => 1  floor(-1.1) => -2 will not provide the round-off function double d; int i; … int i = (int) (d>0 ? d+0.5 : d-0.5);

8. COMP102 Lab 098 Passing Arrays as Parameters 1-D int func(int array[size], int size); int func(const int array[size], int size); 2-D int func(int array[row][col], int row, int col); int func(const int array[row][col], int row, int col); The “ [ ] ” in the formal parameter specification Indicates that the variable is an array It is a good practice to pass the dimension of the array as another parameter Arrays are always passed by reference If the function must not change any element of the array  const should be used

9. COMP102 Lab 099 SUMMARY By the end of this lab, you should be able to: Declare and manipulate  2-D arrays Use mathematical functions provide by  Pass an array to a function  Normally  With const keyword