C中的宏内存占用量？

Question

which one costs more memory? Macro or global variable?

For ex.

#define NAME "subsystem"

const char *name = "subsystem";

And

#define AGE 28
const int age = 28;

For those two cases, do they use same memory? or is global variable size less than macro?

Answer 1

A macro itself consumes no space whatever in an object file. It is a shortcut or mnemonic for expressing source code . The memory required by the compiled source code expressed with the help of macros depends on a variety of things, not least the details of the macro definition and the contexts and frequencies of their use.

In your particular example, the global variables consume space in the compiled object file, but the macros do not. That is an artificial result, however. Where macros representing values are used , the values they represent do consume space in the object file.