Why do books say, \"the compiler allocates space for variables in memory\". Isn\

Question

Why do books say, "the compiler allocates space for variables in memory". Isn't it the executable which does that? I mean, for example, if I write the following program,

#include <iostream>
using namespace std;

int main()
{
   int foo;
   return 0;
}
and compile it, and get an executable (let it be program.exe), now, if I run program.exe, this executable file will itself command to allocate some space for the variable foo. Won't it ? Please explain why books keep on saying, "the compiler will do this...do that".

Explanation / Answer

You are right that the compiler as such is gone when your program actually runs. And if it runs on a different machine, the compiler isn't even available anymore.

I guess this is to make a clear distinction between memory actually allocated by your own code. The compiler will insert some code in your program that does the memory allocation (like using new, malloc or similar commands).

So books use "the compiler does this or that" often to say the compiler added some code that is not explicitly mentioned in your code files. True enough that this isn't exactly what's going on. From this point of view a lot of things mentioned in tutorials would be wrong but would need rather elaborate explanations.

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