Moving To Code

1. 3 Moving To Code

2. 3 More on the Problem-Solving Process • The final step in the problem-solving process is to evaluate and modify (if necessary) the program

3. 3 Coding the Algorithm into a Program Problem Specification: Create a program that prompts the user for two integers, adds the two numbers together, then displays the result.

4. 3 IPO Chart for the Floating Point Adder

5. 3 Assigning Names, Data Types, and Initial Values to the IPO Items • Programmers use the information in the IPO chart to code the algorithm • First, the programmer assigns a descriptive name to each unique input, processing, and output item listed in the IPO chart • In most programming languages, these names can contain only letters, numbers, and the underscore; they cannot contain punctuation characters or spaces • Most Java programmers use lowercase letters for the names, capitalizing the first letter of subsequent words if necessary

6. 3 Assigning Names, Data Types, and Initial Values to the IPO Items • The programmer also assigns a data type to each input, processing, and output item • The data type specifies the type of data each item represents • In addition to assigning both a name and data type to each input, processing, and output item, the programmer also assigns an initial value • This is referred to as initializing the item • Variables are simply computer memory locations that the program will use while running 4

7. 3 Assigning Names, Data Types, and Initial Values to the IPO Items

8. 3 Assigning Names, Data Types, and Initial Values to the IPO Items • The word double, which must be typed using lowercase letters, is a keyword in Java • A keyword is a word that has a special meaning in a programming language • Notice that each of the variable declaration instructions ends with a semicolon (;) • The instruction to declare a variable is considered a statement, which is simply a Java instruction that causes the computer to perform some action after it is executed, or processed, by the computer • All Java statements must end with a semicolon

9. 3 Translating the Algorithm Steps into Java Code • After assigning a name, data type, and initial value to each input, processing, and output item, the programmer then translates each step in the algorithm into one or more Java instructions • In Java, you use streams, which are just sequences of characters, to perform standard input and output operations • The standard output stream is called System.out which refers to the computer screen

10. 3 Translating algorithm steps into Java Code

11. 3 Translating algorithm steps into Java Code

12. 3 Desk-Checking the Program • Desk-check every program to make sure that each step in the algorithm was translated correctly

13. 3 Evaluating and Modifying the Program • The final step in the problem-solving process is to evaluate and modify (if necessary) the program • Programmers often refer to this as the “testing and debugging” step • Testing refers to running (executing) the program, along with sample data, on the computer • Debugging refers to the process of locating and removing any errors, called bugs, in a program

14. 3 Evaluating and Modifyingthe Program • Program errors can be either syntax errors or logic errors • You create a syntax error when you enter an instruction that violates the programming language’s syntax • Logic errors, on the other hand, are much more difficult to find, because they can occur for a variety of reasons