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Date: Sat, 12 Nov 2016 14:12:31 +0000
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Subject: Re: [PHP-DEV] C89 vs. C99
From: ajf@ajf.me (Andrea Faulds)

Hi Derick,

Derick Rethans wrote:
> I would want to write down in our coding guidelines that we should *NOT*
> do declarations after code, as you will no longer have an overview of
> all the types in one place anymore.

That's your preference. Personally, I would really appreciate the 
ability to declare variables later in code.

The main reason for this is that it allows me to minimise the number of 
variables left uninitialised. If you have to declare variables at the 
top of the function, then many of them will be unitialised for some or 
all of the lifetime of the function, or initialised to dummy values. 
This can lead to errors with variables being used before they contain a 
meaningful value (and undefined behaviour), which is the cause of a lot 
of bugs in C code (and indeed in PHP's). It's also easier to end up with 
unused variables this way (whose compiler warnings often get buried or 
ignored), because you would tend to assume that an unitialised variable 
is going to be used later.

There are other benefits, too. For one, it makes the top of a function 
less cluttered: you can define variables where you use them, rather than 
having to list all of them at once. This can make code easier to 
understand, because you only have to worry about variables which are 
currently in use, rather than being distracted by variables which might 
only be initialised or used much later in the function. Plus, because 
this way more variables are initialised at the point of declaration, it 
can make it clearer what a variable's purpose is, because you get both 
the type and the initial value on the same line, rather than possibly on 
different screens. This makes it easier to spot incorrect types and 
initial values, too, which is important given C's, hmm, rather weak type 
system.

If you need to find the type of a previously-declared variable, vim's ? 
command is always at your disposal. But with C99's declarations in the 
function body, now you might actually know what the variable contains 
when you use that command.

Thanks!

-- 
Andrea Faulds
https://ajf.me/