Microsoft C/C++ compiler switch needed for local variable declaration placement

Question

I'm compiling some C files using Microsoft C/C++ and it's complaining about declaring local variables inside a block. Declaring them at the beginning of a block, of course, is fine. What compiler switch can I use to suppress the errors that I'm getting?

Much appreciated,

kris

Answer 1

In C89 and earlier, all block-scope variable declarations must come before any statements. C99 changed this rule, so that declarations and statements may be intermixed as in C++.

Unfortunately, Microsoft has chosen not to support C99 in Visual Studio and has no plans to AFAIK.

Answer 2

In standard C, you can't declare variables anywhere but at the beginning. This is different from C++ where variables can be declared anywhere.

So you must compile the files as if they were C++ via /TP .

See this article for more details.

Answer 3

CL.exe /Tpfilename

It means "compile as C++ regardless of the extension".

Or, to put it another way, what you're doing is illegal in C, so of course it complains. Either change it to C++ or force it to be read as C++.

Answer 4

You can use /TP to force the compiler to compile them as C++ files. I'm not sure if this is what you want, however.