PHP: What are language constructs and why do we need them?

Question

I keep coming across statements like:

• \"echo is a language construct but print is a function and hence has a return value\"
• \"die is a language constr

Answer 1

Language constructs are hard coded into the PHP language. They do not play by normal rules.

For example, whenever you try to access a variable that doesn't exist, you'd get an error. To test whether a variable exists before you access it, you need to consult isset or empty:

if (isset($foo))

If isset was a normal function, you'd get a warning there as well, since you're accessing $foo to pass it into the function isset. Since isset is a language construct though, this works without throwing a warning. That's why the documentation makes a clear distinction between normal functions and language constructs.