Re: ${0} variable basics

> Christoph Becker am Montag, 25. August 2014 - 16:25: > Negin Nickparsa wrote: > > why ${0} is valid but ${0 is not valid? > > it means that curly braces evaluate what's inside them > > No, at least not in the general case. This notation is called "simple > syntax" in the PHP manual[1] and "Variable-Name Creation > Operator/Expression" in the current draft of the PHP language > specification[2]. > > > and that's why we > > cannot have ${0? > > > > variables shouldn't start from 0 so it means that it started from braces? > > if yes why I cannot have ${0? and what is the variable here finally? $0 is > > what it interprets? > > Yes, indeed. However, the notation $0 would be a syntax error. > > > if yes so it is not a legal variable > > Well, actually it is a legal variable, but it might better be avoided to > use such variables. They are confusing, and I can't think of any > advantage in using such variables. Use $zero instead, or maybe an array. > > > I am totally mixed up. > > [1] > > <http://php.net/manual/en/language.types.string.php#language.types.string..parsing.simple> > [2] > > <https://github.com/php/php-langspec/blob/master/spec/10-expressions.md#user-content-variable-name-creation-operator> > > -- > Christoph M. Becker > The manual is not realy clear in this point. My practical expierence says this: an expression like "${....}" is always evaluated as string. ${0} creates a variable named "0", because "0" is not the integer, that would be illegal. And BTW: ${0000.578} gives you "0000_578", because dots in variable names are not allowed and automatically converted to underscores. And it is NOT evaluated to a float. Confusing, and indeed avoid it! Why the hell you really need a variable named "0"? The fabulous type juggling of PHP operates on the values, not the names of variables! -- Niklaus