When to use different integer types?

Question

Programming languages (e.g. c, c++, and java) usually have several types for integer arithmetic:

• signed and unsigned types
• types

Answer 1

One by one to your questions:

1. signed and unsigned : depends on what you need. If you're sure, that the number will be unsigned - use unsigned. This will give you the opportunity to use bigger numbers. For example, a signed char (1B) has range [-128:127], but if it's unsigned - the max value is doubled (you have one more bit to use - sign bit, so unsigned char could be 255 (all bits are 1)

2. short, int, long, long long - these are pretty clear, aren't it? The smallest integer (except char) is short, next one is int, etc. But these ones are platform dependent - int could be 2B (long long ago :D ), 4B (usually). long could be 4B (in 32bit platform), or 8B (on 64bit platform), etc. long long is not standard type in C++ (it will be in C++0x), but usually it's a typedef for int64_t.

3. int32_t vs int - int32_t and other types like this guarantee their size. For example, int32_t is guaranteed to be 32bit, while, as I already said, the size of int is platform dependent.