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Today’s topic:

Today’s topic:. Arithmetic expressions. Arithmetic expressions. binary (two arguments) arithmetic operators +, -, *, /, % (mod or modulus) unary (one arg ) operators -, + Order of operations just like you’d expect: Please Excuse My Dear Aunt Sadie. Can use () to override.

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Today’s topic:

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  1. Today’s topic: • Arithmetic expressions

  2. Arithmetic expressions • binary (two arguments) arithmetic operators • +, -, *, /, % (mod or modulus) • unary (one arg) operators • -, + • Order of operations just like you’d expect: • Please Excuse My Dear Aunt Sadie. • Can use () to override.

  3. Arithmetic expressions • How would we code the following? • Let n be 2 and k be 2n+1.

  4. Arithmetic expressions • How would we code the following? • Let n be 2 and k be 2n+1. int n = 2; int k = 2*n+1; Or int n, k; n = 2; k = 2 * n + 1;

  5. Arithmetic expressions • How would we code the following? • Let n be 2 and k be 2n+1. int n = 2; int k = 2*n+1; Note: The rhs of the equals is always evaluated first and is assigned to the lhs. Therefore, you cannot say: int 2 = n; Or 2*n+1 = k;

  6. Arithmetic expressions • Example from physics: F = M A (force = mass x acceleration). • How would we code this in Java?

  7. Arithmetic expressions • Example from physics: • F = M A (force = mass x acceleration). • How would we code this in Java? double mass = 12.0; double acc = 13.9; double force = mass * acceleration; System.out.println( "force = " + force );

  8. Differences between int and double • int (integer) and double (real numbers) are different. • int is a subset of double but ints are much faster to calculate than doubles • So use ints whenever you can but be aware of the following: int n = 5 / 2; int k = 9 / 10;

  9. Differences between int and double • 5 is an int. • 5.1 is a double. • 5.0 is a double. • 5.7f is a float • Range of values: • int -2 billion to +2 billion • double 4.9x10-324 to 1.8x10308 • float 1.4x10-45 to 3.4x1038

  10. Converting doubles to ints • When we convert, we will typically lose something. • Consider converting 12.9 to an int. There is no int 12.9. • So the compiler will issue a message. To inform the compiler that we really wish to do this, we can use a cast. int i; double d = 12.9; i = (int) d; //What do you think is in i now?

  11. Converting doubles to ints inti; double d = 12.9; i = (int) d; //What do you think is in i now? //how can we round instead?

  12. Let’s check what we’ve learned so far (using jGrasp). class FirstExample { public static void main ( String[] params ) { //arithmetic //output } }

  13. ints and mod (%) • What is the result of the following: int k = 5 / 2; What is the remainder? % is used to calculate the remainder. int remainder = 5 % 2;

  14. Float vs. double • Recall range of values: • double 4.9x10-324 to 1.8x10+308 • float 1.4x10-45 to 3.4x10+38 • Recall that we used a cast to convert a double to an int: • double d = 12.9; • inti = (int) d; • This is because a double won’t fit into an int. Will a double fit into a float?

  15. Increment and decrement operators (++ and --) • What does the following do: • inti = 12; • i = i + 2;

  16. Increment and decrement operators (++ and --) • We often see code like the following: int value = 12; … value = value + 1; … value = value + 1; … value = value + 1;

  17. Increment and decrement operators (++ and --) • We often see code like the following: int value = 12; … value = value + 1; … value = value + 1; … value = value + 1; int value = 12; … value++; //post increment … ++value; //pre increment … value++;

  18. Increment and decrement operators (++ and --) • We often see code like the following: int value = 12; … value = value - 1; … value = value - 1; … value = value - 1; int value = 12; … value--; //post decrement … --value; //pre decrement … value--;

  19. Increment and decrement operators (++ and --) • We can use these operators in expressions as well (but don’t get carried away): int where = 92; int k = 7; where = k++; int j = --where;

  20. Convert the following to Java expressions:

  21. Write a program that . . . class MyProgramTemplate { public static void main ( String param[] ) { System.out.println( "hi there" ); } //end main } //end class

  22. Write a program that . . . Declares a variable for the radius of a circle with a value of 12.7. Calculates the circumference. Calculates the area. Prints out the radius, circumference, and area. class MyProgramTemplate { public static void main ( String param[] ) { System.out.println( "hi there" ); } //end main } //end class

  23. Write a program that . . . Declares a variable for the radius of a circle with a value of 12.7. Calculates the circumference. Calculates the area. Prints out the radius, circumference, and area. class MyProgramTemplate { public static void main ( String param[] ) { System.out.println( "hi there" ); //Declare a variable for the radius of a circle with a value of 12.7. //Calculate the circumference. //Calculate the area. //Print out the radius, circumference, and area. } //end main } //end class

  24. Write a program that . . . What types of things are radius, circumference, and area? class MyProgramTemplate { public static void main ( String param[] ) { System.out.println( "hi there" ); //Declare a variable for the radius of a circle with a value of 12.7. //Calculate the circumference. //Calculate the area. //Print out the radius, circumference, and area. } //end main } //end class

  25. Write a program that . . . public static void main ( String param[] ) { System.out.println( "hi there" ); //Declare a variable for the radius of a circle with a value of 12.7. double radius = 12.7; //Calculate the circumference. //Calculate the area. //Print out the radius, circumference, and area. } //end main

  26. Write a program that . . . public static void main ( String param[] ) { System.out.println( "hi there" ); //Declare a variable for the radius of a circle with a value of 12.7. double radius = 12.7; //Calculate the circumference. double circ = ?; //Calculate the area. //Print out the radius, circumference, and area. } //end main

  27. Write a program that . . . public static void main ( String param[] ) { System.out.println( "hi there" ); //Declare a variable for the radius of a circle with a value of 12.7. double radius = 12.7; //Calculate the circumference. double circ = 2 * 3.14 * radius; //Calculate the area. //Print out the radius, circumference, and area. } //end main

  28. Write a program that . . . public static void main ( String param[] ) { System.out.println( "hi there" ); //Declare a variable for the radius of a circle with a value of 12.7. double radius = 12.7; //Calculate the circumference. double circ = 2 * Math.PI * radius; //Calculate the area. //Print out the radius, circumference, and area. } //end main

  29. Write a program that . . . public static void main ( String param[] ) { System.out.println( "hi there" ); //Declare a variable for the radius of a circle with a value of 12.7. double radius = 12.7; //Calculate the circumference. double circ = 2 * Math.PI * radius; //Calculate the area. double area = Math.PI * radius * radius; //Print out the radius, circumference, and area. } //end main

  30. Write a program that . . . public static void main ( String param[] ) { System.out.println( "hi there" ); //Declare a variable for the radius of a circle with a value of 12.7. double radius = 12.7; //Calculate the circumference. double circ = 2 * Math.PI * radius; //Calculate the area. double area = Math.PI * radius * radius; //Print out the radius, circumference, and area. System.out.println( " radius = " + radius ); ? } //end main

  31. Write a program that . . . public static void main ( String param[] ) { System.out.println( "hi there" ); //Declare a variable for the radius of a circle with a value of 12.7. double radius = 12.7; //Calculate the circumference. double circ = 2 * Math.PI * radius; //Calculate the area. double area = Math.PI * radius * radius; //Print out the radius, circumference, and area. System.out.println( " radius = " + radius ); System.out.println( " circumference = " + circ ); System.out.println( " area = " + area ); System.out.println( " Bye."); } //end main

  32. Write a program that . . . public static void main ( String param[] ) { System.out.println( "hi there" ); //Declare a variable for the radius of a circle with a value of 12.7. double radius = 12.7; //Calculate the circumference. double circ = 2 * Math.PI * radius; //Calculate the area. double area = Math.PI * radius * radius; //Print out the radius, circumference, and area. System.out.print( " radius = " + radius + ", " ); System.out.print( " circumference = " + circ + ", " ); System.out.println( " area = " + area + "." ); System.out.println( " Bye."); } //end main

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