Thread: some questions about memory layout of a c program?

As a general rule, memory layout of the program is irrelevant to the programmer. The only exceptions to this, of which I am aware, are in embedded and operating system kernel programming.

Originally Posted by sweezy

when we talk about memory layout of a cprogram ....is it hapning in compile step or link or when we writ a c program immediatly?

The linker (last stage) is generally responsible for the final memory layout.

Originally Posted by sweezy

another point :text segment is it a-out?

If you're talking about the a.out output of gcc, the text segment is just one part of it. There are several other segments that are part of the final output of the build process.

Originally Posted by sweezy

as i understood the text segment is machine instruction it's often read only to prevent a program from accidentally modifying its instructions.

This is often true. Most modern architectures have a way to protect code from being written, after it's loaded.

Originally Posted by sweezy

so it's like a contant in memory,is'nt it?

You could look at it this way.

Originally Posted by sweezy

and preporessore directive(such as #include stdin.h or #define ..) where is it in memory layout? i mean where is its position or section in memory ?

It isn't. Nothing of the source generally remains in the binary output of the build process, with the exception of literal strings.