How to Write a Computer Program Everyone at one point in their life has had to solve a problem. In school we are taught problem solving techniques such as: identify the problem, analyze the problem, identify possible solutions, analyze and compare possible solutions, implement solutions and review the results. Writing a computer program is essentially solving a problem, so it follows similar steps. The steps in writing a computer program are: analyze the problem, design the program, code the program and test the program. As there is a vast amount of computer languages that programs can be written in, these steps are not language specific and more are a form of programming prewriting. In analyzing the problem you first need to answer a few questions. The most important of these is what result do you want? The result will be the output of the program. Next, you need to determine what information needs to be inputted into your program to receive the desired output. Lastly, you need to determine how you are going to take your input information and turn it into your output information. An example problem is that you want to determine the price of items before and after tax. Your inputs would be: the price of the item, expressed as ItemPrice; the amount of tax, expressed as TaxRate; and the amount of that item, expressed as ItemQuantity. The output would then be the amount of the item before and after tax has been included, expressed as OriginalPrice and TaxPrice respectively. One way to solve this would be to use the following equations: ItemPrice * ItemQuantity = OriginalPrice and then OriginalPrice * TaxRate + OriginalPrice = TaxPrice. Once the problem has been analyzed, the variables identified, and the algorithm has been determined, it is time to design the program. Designing the program is no more than creating a set of step by step instructions, starting at inputting your variables, to arriving at the solution or output. If you were going to give someone step by step directions to get from their home to yours, you would probably start the directions by telling them which way to head on the nearest main road. You wouldn’t say take a left out of your driveway, then take the first right and so on. We leave out obvious steps or small ones because humans can think outside of the parameters of the information given. If you were to give directions to your computer you would need to include steps such as: put on the left shoe, tie the left shoe; put on the right shoe, tie the right shoe; walk to your car keys, pick up the car keys, and so on. You must detail every last step because a computer can only do what it is told, it cannot infer anything. That is why the design is so important; it will establish every step that needs to be taken. The design can be done in plain English, or as diagrams similar to flow charts. An example of a simple design is:
Input the price of an item (to variable ItemPrice) from user
Input the quantity of an item (to variable ItemQuantity) from user
Input the tax amount (to variable TaxRate) from user
Calculate OrigianlPrice as: ItemPrice * ItemQuantity
Calculate TaxPrice as: OriginalPrice * Taxrate + OriginalPrice
Output OriginalPrice and TaxPrice

Every step and function is specific, and leaves no gaps in the instruction. Now we can move to the coding of the program.
Once problem has been analyzed, and the program designed, you can start to code the program. Programming the code involves taking that blueprint created in the design process, and translating it into the programming language you are going to use. In addition to the design you created, when coding, you will also add descriptions into your code to document the program. This documentation will only be visible in the code and not on the program the user sees. There are several reasons to do this, such as explaining the code so other programmers can see what you did, and why, and to give a little bit of information like your name and the program's name. An example code looks like this:

// Program name: Price Calculator
// Author Name: Clifton Ekkert
// Description: This program calculates the total price of items before and after tax. Declare ItemPrice as Float
Declare ItemQuantity as Integer
Declare OriginalPrice as Float
Declare TaxRate as Float
Delcare TaxPrice as Float
Write “This program calculates the total price of items before and after tax.”
Write “Enter Item price in decimal format. i.e. 2.50"
Input ItemPrice
Write “Enter item quantity as a whole number.”
Input ItemQuantity
Write “Enter the tax percentage in decimal form.”
Input TaxRate
Set OriginalPrice = ItemPrice * ItemQuantity
Set TaxPrice = OriginalPrice * TaxRate + OriginalPrice
Write "The total cost before tax is " + OriginalPrice + " dollars."
Write "The total cost after tax is " + TaxPrice + " dollars."

For this program, declarations are defining what type of input each variable needs to be. In this instance, float means a decimal number, and integer means a whole number. In addition, write is the command to display text to the user of the program, and input is the variable required to be provided by the user. Finally, after the program is coded, it must be tested. The program must be run to ensure it performs all steps and gives an output. If it does not output a solution to the problem, you will need to examine the code for where you went wrong. If the program does provide a solution, a wise step would be to verify the answer is correct by performing hand calculations to verify the accuracy of the solution, with two different sets of numbers. In conclusion, a computer program is a tool to solve a problem, and to solve that problem you must follow the problem solving steps. In addition you will need to follow the steps of programming: Analyze the problem, design the program, code the program and test the program. Without following these steps you may still be able to create a functional program but will most likely spend more time fixing errors and attempting to organize the program than if you follow these steps.