In C (or C' textbook), "static" is used as internal linkage, which declare the static variable only existing as different instances in the defferent source file. On the other hand, static member of class seems to be the same instance (Singleton in C++ uses that).
How is "static" interpreted in terms of memory arrangement?(I heard static variable is assigned into text segment in each process)
How is "static" interpreted in terms of memory arrangement
The compiler is free to put static variables wherever it wants. You can't portably rely on the placement. That said, I suspect that statics are usually stored along side the globals. It seems to me that that would be easiest for the compiler writer.
I heard static variable is assigned into text segment in each process
The text segment is where the code goes and is often (usually?) read-only, so you can't put any non-const variables there.
I don't think I can give a good answer because I don't know enough about the ancient history of C and C++, but I'm guessing that static made sense because it makes the variable have static storage duration.