Programming

Algorithm A computer program is a solution to a problem. An algorithm is the logical design used to accomplish a specific objective. Algorithms are well-ordered. Algorithms have unambiguous operations. Algorithms have effectively computable operations. Algorithms produce a result. Algorithms halt in a finite amount of time.

Syntax / Information System Syntax refers to the specific rules of a programming language. An information system is a combination of people and technology that collect, organize, and process data to produce information.

Information System Cont. An information system must do at least three things: input data into the system process data within the system output resulting information from the system

Variable For now they will be either for strings or numbers Memory location that can be accessed and changed by developer code Can store only one piece of data at any time Variables have a data type For now they will be either for strings or numbers

Rules for Naming Variables Name must begin with a letter. Name can contain only letters, numbers, and the underscore. No punctuation characters or spaces are allowed. Name cannot exceed 255 characters. Name cannot be a reserved word. public, int, private

Rules for Naming Variables cont. Should be meaningful and descriptive representing the variable’s purpose Short names are bad Capitalize words for readability (Pascal case) InterestRate Many programmers use a prefix to show the variables data type decInterestRate

Input Statements An input statement accepts data from the user and stores that data into a variable In Visual Logic a Prompt can be added to request input by clicking on More>>

Simple Programming Formats

Assignment Statements (data into memory) The assignment statement can be used to perform a calculation and store the result. An expression is a value-returning code element, such as a variable or mathematical formula. The expression on the right hand side is evaluated and stored in the variable on the left hand side.

How to Write Arithmetic Expressions Don’t forget the rules of precedence when writing expressions.

Output Statements Types of output include Screen output Printed output Sound output Saving to storage devices Your output should be appealing to the user. Use & and multi-line when appropriate. Your output should provide the answer to the problem.

Pseudocode/Flow Charts Human readable Not written towards one language Well defined Little to no syntax Use of keywords START WHILE FOR IF NOT TRUE

Develop a solution to a problem Jake has a car with an 8-gallon fuel tank. Jake fills his tank with gas and then drives 60 miles to a friend's house. When he gets to his friend's house, he has 6 gallons left in his fuel tank. Write a program that uses three input elements to enter values for tank size, miles traveled and gallons left. The program should calculate and display how many miles Jake can drive on a full tank of gas.

Jakes Problem Identify the Inputs, processing and outputs. Inputs (variables) Processing (assignment statements) Output (provide answer)

Intrinsic Functions Intrinsic functions are predefined commands that provide developers with common, helpful functionality. A function takes one or more arguments/parameters. A function returns a result which can be assigned to a variable, output, or used in an expression.

Intrinsic Functions (cont.) Length(strVariable) The number of characters in the string.