variable scope

[alpine]

Hi,

I'm just starting to play around with PHP and I just ran into my first stumbling block.

I wrote a little code, created some functions, created some global variables in an include file, the usual. Then after quite a bit of debugging, I learned that global variables are not visible within functions.

I'm having a tough time getting my head around this. I had planned on having an include file with all my SQL statements as variables and using them from within various functions. But these won't be visible from within functions.

What's the common way of handling this?

Thanks.

[laserlight]

1. Pass the variables as arguments to the function.

2. Use the global keyword to allow access to those variables from within the function.

[BuzzLY]

These example illustrate laserlight's suggestions:

$foo = "bar";

function fooBar1() {
  // this will echo nothing, or ""
  echo $foo;
}

function fooBar2() {
  // this will echo "bar"
  global $foo;
  echo $foo;
}

function fooBar3($foo) {
  // this will echo "bar"
  echo $foo;
}

In other words, use the global keyword INSIDE the function.

This may be a little confusing. In many languages, such as C, variables are always global unless otherwise overwritten within a function. It's easier in PHP to think of all variables being global, but local within a function. If you want to use the global "version" of the variable, you tell that function to "go ahead and use the global variable" by using the global keyword.

Incidentally, the opposite of this is the keyword "static." Ordinarily, a local variable inside a function is only available to the function. If you want the variable to be available after the function is done, then you would use the "static" keyword.

Check out the PHP manual for more information.

[alpine]

Thanks for the pointers. In the meantime, I've been trying to design things without the use of global vars, but sometimes, you just need them.