Introduction to Computer Programming

1. Introduction to Computer Programming Recitation 2 Ihsan Ayyub Qazi

2. Agenda • Practice • Practice • Practice

3. What is the output of the program? public class Test { public static void main (String args []) { int x = 10, y = 3; double t = 3.0, z = 0.0; z = x/3; System.out.println(z); z = x/(double)3; System.out.println(z); z = (double)(x/3); System.out.println(z); z = x/t; System.out.println(z); } }

4. Output? public class Test { public static void main(String args []) { char letter = 'A'; int val = 0; double d = 0.0; byte b = 0; val = letter; System.out.println(val); d = letter; System.out.println(d); b = letter; System.out.println(b); } } Recall “narrowing conversion” To avoid a compilaton error explicit cast must be done !! Why? The compiler wants to make sure that the programmer knows what he/she is doing and didn’t make a mistake

5. Output? public class Test { public static void main(String args []) { char letter_1 = 65, letter_2 = 66; char temp; temp = letter_1; letter_1 = letter_2; letter_2 = temp; System.out.println(letter_1); System.out.println(letter_1); System.out.println((int) letter_1); System.out.println((int) letter_1); } }

6. Output? public class Test { public static void main(String args []) { int age = 0, height = 0, sum = 0; 15 = age; 20 = height; sum = age + height; System.out.println(sum); } } The operand to the left of the assignment “=“ operator always has to have a variable ! Why?

7. Output? public class Test { public static void main(String args []) { int x = 0, 34 = 0; 34 = 13; System.out.println(34); } } How about x=34?

8. Output? public class Test { public static void main(String args []) { int age = 21; short height = 78, sum = 0; sum = age + height; System.out.println(sum); } }

9. Output? public class Test { public static void main(String args []) { String str = "This is a class on computer programming"; String abc = "ABC"; char c, d; int val; System.out.println( str.toUpperCase() ); val = abc.charAt(0) + 1; c = (char) val; System.out.println(c); } }

10. Output? (Challenge Question) public class Test { public static void main(String args []) { int x = 10, y = 3; double t = 3.0, z = 0.0; z = (double)(x/3); System.out.println(z); z = (char)x/3; System.out.println(z); } }

11. THANKS !!