Question

I have a API like this,

class IoType {
......
    StatusType writeBytes(......, size_t& bytesWritten);
    StatusType writeObjects(......, size_t& objsWritten);
};

A senior member of the team who I respect seems to have a problem with the type size_t and suggest that I use C99 types. I know it sounds stupid but I always think c99 types like uint32_t and uint64_t look ugly. I do use them but only when it’s really necessary, for instance when I need to serialize/deserialize a structure, I do want to be specific about the sizes of my data members.

What are the arguments against using size_t? I know it’s not a real type but if I know for sure even a 32-bit integer is enough for me and a size type seems to be appropriate for number of bytes or number of objects, etc.

Answer 1

Use exact-size types like uint32_t whenever you’re dealing with serialization of any sort (binary files, networking, etc.). Use size_t whenever you’re dealing with the size of an object in memory—that’s what it’s intended for. All of the functions that deal with object sizes, like malloc, strlen, and the sizeof operator all size_t.

If you use size_t correctly, your program will be maximally portable, and it will not waste time and memory on platforms where it doesn’t need to. On 32-bit platforms, a size_t will be 32 bits—if you instead used a uint64_t, you’d waste time and space. Conversely, on 64-bit platforms, a size_t will be 64 bits—if you instead used a uint32_t, your program could behave incorrectly (maybe even crash or open up a security vulnerability) if it ever had to deal with a piece of memory larger than 4 GB.