The size_t and ssize_t of UNIX programming

I'm pretty sure and sure to tell you that ssize_t is a signed integer, equivalent to int on a 32-bit machine, equivalent to a long int on a 64-bit machine, is there any difference between it and the Long data type? is actually the same. size_t is an unsigned ssize_t, that is unsigned long/unsigned int (under 32 bits), different compilers or systems may differ, mainly because int and long are the same on 32-bit machines. In 64 bit no test, but see Baidu Encyclopedia, size_t in 64 bit is 64 bit, then the correct definition of size_t should be typedef unsigned long size_t.

The size_t and ssize_t of UNIX programming