COMP102 – Programming Fundamentals I LA2B (Mon 5-7pm) LA2E (Fri 3-5pm) LA2F (Fri 5-7pm) TA: Jackie Lo

More on Array  CANNOT copy all elements of one array into another with an assignment statement array2 = array1;  Must use a loop instead for (int i=0; i<array_size; i++)  array2[i] = array1[i]; Lecture Review

Passing Arrays to Functions  Passing array as parameter = pass by reference  NO & sign To ensure no modification inside function  i.e. all elements in the array are read-only  Add a const modifier before the array parameter double func(const int array[])

Lecture Review Declare functions with array as parameter  1-D int func (int array[], int row); int func (int array[ ]);  2-D int func (int array[][ ], int row); int func (int array[ ][ ]);  E.g. int func1(int a[][]);// invalid! int func2(int a[][3]);// valid!

Lecture Review More E.g. void fun1(int a) {…} void main() { int lab_score[10][35]; fun1(lab_score[0][1]); } void fun1(int a[]) {…} void main() { int midterm[35]; fun1(midterm); } void fun1(int lab_score[][10]) {…} void main() { int lab_score[35][10]; fun1(lab_score); }

Lecture Review More on Char array  String A sequence of characters  Stored in an array of type char Ending  With the null character  ' \0 '

Lecture Review A character string is a sequence of characters enclosed in double quotes ( “ … ” ) E.g.  char s1[2] = “a”; s1[0] = ‘a’ s1[1] = ‘\0’  char b[] = “abcdef”;  char b[10] = “abcdef”;  char str[] = “”; It is called an empty string Uses one byte to store the null character (‘\0’)  char str[10]=“ ”; // invalid ‘a’‘a’‘b’‘b’‘c’‘c’‘d’‘d’‘e’‘e’‘f’‘f’‘ \0 ’‘a’‘a’‘b’‘b’‘c’‘c’‘d’‘d’‘e’‘e’‘f’‘f’ ???

Lecture Review cin stream operation  char s[10];  cin >> s; A string with space ( ‘ ’ ) CANNOT be read properly cin.getline  Syntax cin.getline(char dst[], int size, char delimiter)  When the delimiter character is encountered  A string is stored in character string dst  With maximum length of size, including the null character ( ‘ \0 ’ ) Note  delimiter character is optional, default is ‘ \n ’

Lecture Review What is the output of str in each case if the input is “COMP102 is i-chi-ban” ? char str[30]; cin.getline(str, 10); char str[30]; cin.getline(str, 10, ‘2’); char str[30]; cin.getline(str, 16, ‘-’); char str[30]; cin.getline(str, 25); char str[30]; cin.getline(str, 25, ‘i’); COMP102 i COMP10 COMP102 is i COMP102 COMP102 is i-chi-ban

Lecture Review String Copy  NEVER use ‘=’, except assign real val when declare char str[16] = “Hello World”; char str1[16] = str;  Copy source string into destination string void strcpy(char dest[], const char src[]); E.g.  strcpy(str1, str);

Lecture Review String Length  int strlen(const char[]); Returns length of string, NOT include ‘ \0 ’  E.g. 1. int str_length = strlen(“abcde”); 2. char str[10] = “abcde”; int str_length = strlen(str);

Lecture Review String Compare  NEVER use ( ==,, >= )  Compares strings string1 and string2 int strcmp(char string1[], char string2[]); E.g.  int result = strcmp(s1, s2);  if (s1 result = -1 (true)  if (s1 == s2) => result = 0 (false)  if (s1 > s2) => result = 1 (true)

Common Error The operator “ == ” doesn't test two strings for equality  E.g. if (string1 == string2)// Invalid! Use strcmp function instead  if (!strcmp(string1, string2))

SUMMARY By the end of this lab, you should be able to:  Pass array to function  Declare and manipulate char array as string

Lab11 Download the template from website