Programming in Java I

Lecture Notes 6, csc211

Prepared by: Anthony Larrain

These notes serve as an outline to the lecture, they are not intended to be complete. You should be reading the assigned sections. During class I may include or omit certain topics.

Finding the average of a sequence of non-negative integers

Write a Java program to compute the average of a set of exam scores rounded to two places.

Use the following pseudocode

Calculator program

Write a program that mimics a calculator. The program should take as input two integers and an arithmetic operation(+,-,* or /) to be performed. It should then output the numbers, the operator, and the result. (For division, if the denominator is 0, output an appropriate message.)

The for statement

• A count controlled construct.
• Typically used when it can be determined the number of times the loop body should execute.

for (initialization; condition; update) {
    execute this block if the condition is true
}

// sum of the first positive 100 integers

int i, sum = 0;
for (i = 1; i <= 100; i++){
    sum += i;                      //equivalent to sum = sum + i;
}

• The initialization, condition and update sections are separated by semi colons ;
• The variable i, in the example statement is called a control variable.
• It keeps track of the number of repetitions.
• The increment can be by any amount, positive or negative.
• The initialization component can also include a declaration of the control variable.

int sum = 0;
for (int i = 1; i <= 100; i++){
    sum += i; //equivalent to sum = sum + 1;
}

• The control variable can be incremented or decremented by any amount.

//  The sum of even integers up to and including 100.

int sum = 0;
for(int i = 2; i <= 100; i += 2) {
   sum += i;
}

Blast off

for(int i = 10; i > 0; i--) {
    System.out.println(i);
}
System.out.println("Blast Off");

// the first 10 powers of 2

for(int i = 1; i < 10; i++){
   System.out.println(Math.pow(2,i));
}