Creating the text in Java

Printer QR in Java Creating the text

After you know these variables (verseNum and distraction), it s pretty easy to construct the output text: var text = The ants text += verseNum + hurrah \n ; text += The ants go text += verseNum + hurrah \n ; text += The ants go text += verseNum + text += the little text += distraction; return text; } // end verse1 go marching ; by + verseNum + hurrah, marching ; by + verseNum + hurrah, marching ; by + verseNum; one stops to ;

There s a whole lotta concatenatin going on, but it s essentially the same code as the original verse() function This one s just a lot more flexible, because it can handle any verse (Well, it can if the function has been preloaded to understand how to handle the particular verse number More on that soon)

A function is much like an independent mini-program Any variable you create inside a function only has meaning inside that function When the function finishes executing, its variables disappear! This is actually a really good thing A major program will have hundreds of variables They can be very difficult to keep track of It s possible to re-use a variable name without knowing it, or have a value changed inadvertently When you break your code into functions, each function has its own independent set of variables You don t have to worry about whether the variables will cause problems elsewhere

You can also define variables at the main (script) level These variables are considered global variables A global variable is available at the main level and inside each function A local variable (one defined inside a function) has meaning only inside the function The concept of local-versus-global functions is sometimes referred to as scope Local variables are kind of like local police who have a limited geographical jurisdiction, but are very useful within that space They know the neighborhood Sometimes you ll encounter situations that cross local jurisdictions This is the kind of situation that requires a state trooper or the FBI Local variables are local cops, and global variables are the FBI In general, try to make as many of your variables local as possible The only time you really need a global variable is when you want some information to be used in multiple functions

To understand the implications of variable scope, take a look at scope html: <script type = text/javascript > //<![CDATA[ //from scopehtml var globalVar = I m global! ; function myFunction(){ var localVar = I m local ; consolelog(localVar); } myFunction(); //]]> </script> This program defines two variables globalVar is defined in the main code, and localVar is defined inside a function If you run the program in Debug mode while watching the variables, you can see how they behave Figure 5-2 shows what the program looks like early in the run

Note that localVar doesn t have meaning until the function is called, so it remains undefined until the computer gets to that part of the code Step ahead a few lines, and you ll see localVar has a value, as shown in Figure 5-3 Be sure to use the Step Into technique for walking through a program rather than Step Over for this example When Step Over encounters a function, it runs the entire function as one line If you want to look into the function and see what s happening inside it (as you do here), use Step Into Please look at 4 if you need a refresher on using debugging modes

globalVar has a value, but localVar does not because the program has not yet reached the funtion containing localVar