In programming, you will utilize math a lot…not complex math, but math none the less. So make sure you know addition, subtraction, division and multiplication. In this post, I want to address addition.
Of course, when you add two numbers together, you utilize the plus (+) symbol. With this particular operator, you have to be aware of the data types you are adding together. The plus (+) operator is used not only for addition, but also for concatenation, which is connecting two items together and making them one.
Let’s look at some examples.
First, plain addition…
[code lang=”js”]
// Declare two number variables and a total variable
var firstNum = 1;
var secondNum = 2;
var total = 0;
// Add two variables together and store them in the total
total = firstNum + secondNum;
// Output total to screen
document.write(total);
[/code]
The aforementioned code would result in the number ‘3’ being output to the screen.
Now, let’s look at concatenation…
[code lang=”js”]
// declare to string variables and a combined variable
var firstString = "Java";
var secondString = "Script";
var combinedString = "";
// Concatenate the two variables into one and store it in the combined variable
combinedString = firstString + secondString;
// Output code to the screen
document.write(CombinedString);
[/code]
The aforementioned could would result in the word “JavaScript” being output to the screen.
So why is this important to keep in mind? Well, sometimes a number is not a number. For example…
[code lang=”js”]
// Declare a variable with numbered value strings
var testVar = "1" + "2";
// Output the variable to the screen
document.write(testVar);
[/code]
The aforementioned code would result in the text number of “12” being output to the screen.
Now, sometimes, depending on the language, which I am using JavaScript, the language interpreter/compiler will attempt to make type adjustments on the fly. So depending on how you use the numbered string, it could result in a correct calculation. My recommendation is to always test to ensure you are using a number. For example, in JavaScript whenever you prompt the user for information, it always comes through as a string, even if they put in a number. You can use the Number() function to it from a string to an integer.
Happy Coding!
Clay Hess
