Omitting the datatype (e.g. "unsigned" instead of "unsigned int")

Question

I know that if the data type declaration is omitted in C/C++ code in such way: unsigned test=5;, the compiler automatically makes this variable an int (an unsigned int in this case). I've heard that it's a C standard and it will work in all compilers.

But I've also heard that doing this is considered a bad practice.

What do you think? Should I really type unsigned int instead of just unsigned?

Are short, long and long long also datatypes?

Answer 1

unsigned is a data type! And it happens to alias to unsigned int.

When you’re writing unsigned x; you are not omitting any data type.

This is completely different from “default int” which exists in C (but not in C++!) where you really omit the type on a declaration and C automatically infers that type to be int.

As for style, I personally prefer to be explicit and thus to write unsigned int. On the other hand, I’m currently involved in a library where it’s convention to just write unsigned, so I do that instead.

Answer 2

I would even take it one step further and use stdint's uint32_t type.
It might be a matter of taste, but I prefer to know what primitive I'm using over some ancient consideration of optimising per platform.