| PHP - Function Control |
PHP - Function Control
A function is a named sequence of code statements that can optionally accept parameters and return a value. A function call is an expression that has a value; its value is the returned value from the function. PHP provides a large number of internal functions. The "Function Reference" section lists all of the commonly available functions. PHP also supports user-definable functions. To define a function, use the function keyword. For example:
function soundcheck($a, $b, $c) {
return "Testing, $a, $b, $c";
}
When you define a function, be careful what name you give it. In particular, you need to make sure that the name does not conflict with any of the internal PHP functions. If you do use a function name that conflicts with an internal function, you get the following error:
Fatal error: Can't redeclare already declared function in
filename on line N
After you define a function, you call it by passing in the appropriate arguments. For example:
echo soundcheck(4, 5, 6);
You can also create functions with optional parameters. To do so, you set a default value for each optional parameter in the definition, using C++ style. For example, here's how to make all the parameters to the soundcheck() function optional:
function soundcheck($a=1, $b=2, $c=3) {
return "Testing, $a, $b, $c";
}
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